Commissioning of DC & UPS Systems

Note: The source of the technical material in this volume is the ProfessionalEngineering Development Program (PEDP) of Engineering Services.

Warning: The material contained in this document was developed for SaudiAramco and is intended for the exclusive use of Saudi Aramcosemployees. Any material contained in this document which is notalready in the public domain may not be copied, reproduced, sold, given,or disclosed to third parties, or otherwise used in whole, or in part,without the written permission of the Vice President, EngineeringServices, Saudi Aramco.

Chapter : Electrical For additional information on this subject, contactFile Reference: EEX21106 W.A. Roussel on 874-1320

Engineering EncyclopediaSaudi Aramco DeskTop Standards

Directing the Start-Up andCommissioning of DC/UPS Systems

Engineering Encyclopedia Electrical

Directing the Start-Up and Commissioning of DC/UPS Systems

Saudi Aramco DeskTop Standards

CONTENTS PAGES

BATTERY SAFETY REQUIREMENTS: HAZARDS ANDPRECAUTIONS ..................................................................................................... 1

Building Support Systems ........................................................................... 1Electrolyte ................................................................................................... 2

Hazards Present................................................................................ 2Precautions for Reducing or for Eliminating Hazards .....................3

Electric Shock..............................................................................................4Hazards Present................................................................................ 4Precautions for Reducing or for Eliminating Hazards .....................6

Hydrogen Gas..............................................................................................6Hazards Present................................................................................ 7Precautions for Reducing or for Eliminating Hazards .....................7

BATTERY SYSTEM START-UP AND COMMISSIONING...............................8Pre-Startup and Commissioning Checks/Verification ................................. 8Initial Electrolyte Filling.............................................................................. 9Initial Charging Procedures....................................................................... 13

Lead-Antimony Batteries ...............................................................13Lead-Calcium Batteries.................................................................. 16

Cell Voltage and Specific Gravity Measurements..................................... 17Cell Voltage ................................................................................... 17Specific Gravity ............................................................................. 21



Saudi Aramco DeskTop Standards

UPS SYSTEM START-UP AND COMMISSIONING........................................ 29Verifying Proper Electrical Connections................................................... 29Verifying Initial System Set-Up ................................................................30

Initial Conditions ........................................................................... 30System Setpoints............................................................................ 31Calibration Checks......................................................................... 35Switching Functions ...................................................................... 35

Simulation of Line Power Source Loss .....................................................36INTERPRETING START-UP AND COMMISSIONING TEST RESULTS....... 38

Battery System Start-Up and Commissioning ........................................... 38Battery Charger Start-Up and Commissioning.......................................... 41UPS System Start-Up and Commissioning ............................................... 42

WORK AID 1: PROCEDURES AND CRITERIA FROM SADP-P-103, IEEE 446, AND ESTABLISHED ENGINEERINGPRACTICES FOR INTERPRETING START-UP ANDCOMMISSIONING TEST RESULTS........................................ 44

Procedure and Acceptable Values for Interpreting Start-Up andCommissioning Data ................................................................................. 44

GLOSSARY ......................................................................................................... 58



Saudi Aramco DeskTop Standards 1

BATTERY SAFETY REQUIREMENTS: HAZARDS AND PRECAUTIONS

The Electrical Engineer must recognize the potential dangers and hazards that are associatedwith batteries and battery systems. Through knowledge of the potential hazards, the ElectricalEngineer can adequately prepare the technicians to eliminate the source of a hazard or tominimize the effects of a hazard. Failure to recognize or consider the areas of potentialhazards could result in equipment damage or in injury to personnel. The following topics thatare pertinent to potential hazards are discussed in this section:

Building Support Systems Electrolyte Electric Shock Hydrogen Gas

Building Support Systems

The hazards when working with secondary batteries are increased when building supportsystems are non-existent or are inoperable. One responsibility of the start-up engineer is toverify the existence of these systems and their functional operation prior to initiating start-upprocedures on the battery and UPS systems.

The building support systems and the verifications that are required for each system are asfollows:

For battery rooms that use pressurized air systems, verify that the monitoringsystem actuates the local alarm on a loss of room pressurization.

For battery rooms that use air exhaust systems, verify that the area exhaust fanoperates.

Verify that the battery room/UPS room is air conditioned to 25oC. If thebattery room temperature is below 25oC, cell capacity is reduced. If the batteryroom temperature is consistently higher than 29oC, cell life is shortened .

Verify that eyewash facilities (portable or permanent) are installed andoperable. (Eyewash facilities are not required for sealed battery installations.)

Verify that floor drains are functional.

Verify that portable water facilities are available for cleanup and flushing ofelectrolyte spills.




Verify that the following safety items and test equipment are installed or areavailable for immediate use:

- Chemical worker's goggles.

- Face shield.

- Apron.

- Acid/alkaline resistant gloves.

- A supply of bicarbonate of soda to neutralize sulfuric acid.

- A supply of citric acid to neutralize potassium hydroxide (nickel-cadmium battery rooms).

- Cell lifting straps and strap spreaders.

- Thermometer to measure electrolyte temperature.

- Hydrometer with temperature correcting scale to measure electrolytespecific gravity.

Electrolyte

Because of the abundance of electrolyte in large storage batteries, and because of thefrequency with which electrolyte is handled, electrolyte is one of the major hazards that isassociated with batteries. The Electrical Engineer must be familiar with the hazards that areassociated with electrolytes and with the precautions to be taken to minimize these hazards.

Hazards Present

Electrolyte presents a hazard to equipment and personnel because of the electrolyte's acidicand alkaline properties. If electrolyte is improperly handled, the electrolyte will causedamage to the battery and to the battery rack, or it will cause injury to personnel.

The hazard for equipment occurs from electrolyte that is spilled or dropped onto theequipment. Electrolyte is most likely to be spilled on the battery or on adjacent equipmentduring the initial battery fill and during the periodic electrolyte testing. If the spilledelectrolyte is not properly neutralized and removed, the following problems could occur:

The affected equipment will corrode and deteriorate over time.




The electrolyte will contaminate the battery casing and will cause batterygrounds.

In installations that use wood support channels, excessive electrolyte that isabsorbed into the wood can result in cell discharge through the saturated wood.

The electrolyte that is spilled on the battery connections could impair electricalcurrent flow.

Personal hazards from electrolyte occur as a result of direct contact with electrolyte. Theelectrolyte that is used in the battery, sulfuric acid (acidic), or potassium hydroxide (alkaline),can cause skin burns, eye injuries, and clothing damage. Direct contact with the electrolytecan occur while the battery is being initially filled, during the periodic electrolyte testing, oras a result of casual contact with spilled electrolyte. Electrolyte that is spilled on the flooralso produces slippery conditions that could be hazardous to personnel.

Precautions for Reducing or for Eliminating Hazards

The Electrical Engineer must be aware of the precautions that should be taken to reduce or toeliminate the hazards that are associated with battery electrolytes. The majority of the hazardsto personnel and equipment occur from handling of the electrolyte during the filling and/ortesting process. The use of common sense and good housekeeping practices will reduce oreliminate most of the hazards. The following guidelines will minimize the potential hazardsthat battery electrolytes present:

All spills from the battery equipment should be rinsed away, and the spill areashould be neutralized. After neutralization of the spill area, a final rinse shouldbe performed through use of potable water.

A bicarbonate of soda solution (100 grams per liter of potable water) should beused to neutralize sulfuric acid.

A citric acid solution (90 grams per liter of potable water) should be used toneutralize potassium hydroxide.

When working with electrolyte, personnel are to wear protective clothing,which is provided as part of the battery room safety equipment.

Extreme care should be used in the removal of a cell vent cap or an arcsuppressor. In the unlikely event of cell pressurization, such a removal couldresult in the release of electrolyte.




Only battery handling straps and strap spreaders that are approved by themanufacturer should be used to transport or to physically handle the batterycells.

When hydrometer tests are performed, the electrolyte should be removed withcare to avoid unnecessary splashes and spills.

To avoid overfill and splashes, electrolyte should be added to battery cellsthrough use of proper cell electrolyte filling equipment.

Electric Shock

All personnel who work on or near batteries must remember that the possibility of electricshock exists at all times. The following topics that are pertinent to electrical shock arediscussed in this section:

Hazards Present Precautions for Reducing or for Eliminating Hazards

Hazards Present

Charged batteries that are connected in large series strings have the ability to deliver highshort circuit currents. Because the short circuit current capability of these cells (batteries) canreach many thousands of amperes, the exposed conductors of a charged battery should betreated with respect and caution. Severe burns can result if metallic objects (such as jewelryand hand tools) make contact between two opposing cell terminals.

Electrical shock hazards always exist with any series string of batteries. The shock hazardthat batteries present is best illustrated through application of Ohm's Law (E = IR). Forexample, the resistance of damp skin can be as low as 300_, and the amount of current flowthat normally is considered lethal is 0.1A. As Ohm's Law shows, a 30V (300_ X 0.1A = 30V)series string of batteries could produce a lethal shock.

Electric shock hazards normally are only associated with large, high voltage batteryinstallations; however, even smaller batteries, such as those found in communicationsequipment, forklifts, and automobiles, can pose an electric shock hazard. The most commoncauses of electric shock from a battery are simultaneous contact of the positive and negativeterminals (by shorting out the positive and negative terminals with an uninsulated tool) orcontact of a cell terminal with the common system ground. In addition to the electrical shockhazard, shorting the positive and negative terminals can damage the battery.

Electrical shock hazards also can exist when the battery casing or the battery rack is touched.This hazard can exist because of dirty battery casings and electrolyte spills. The electrolyte




spills and the dirt can cause a low resistance current path from the battery terminal to thebattery casing. In this situation, a shock hazard will exist if contact is made between thebattery case and system ground.





To reduce or eliminate electrical shock hazards, all personnel who work on or near batteriesmust be fully aware of hazards that are associated with batteries and the affects of electricalshock. The precautions for the reduction or the elimination of hazards of electrical shock in abattery room are the same as the precautions for all electrical systems. Common sense shouldprevail in instances that concern electrical equipment maintenance. Also, the followingguidelines should be observed:

Electrical safety gloves should be worn for work with the battery cables and thebattery connections.

Electrical safety goggles should be worn to protect against possible flashburnsthat are caused by short circuits.

Electrical safety mats should be used to cover all exposed electrical parts in thework vicinity.

All metal articles such as watches, rings, necklaces, and belt buckles should beremoved from the body and from the clothing.

All tools should be insulated so that no more than three inches of exposedmetal exists.

All tools should be properly secured during maintenance and should not be leftunattended on the tops of the battery cells.

All electrolyte spills should be immediately cleaned up, neutralized, andwashed down.

In case of an emergency, maintenance personnel should be qualified to performfirst aid and cardiopulmonary resuscitation (CPR).

Hydrogen Gas

The potential hazards that are presented by hydrogen gas are most prevalent during chargeand discharge operations in the battery room. This section will cover the following topics thatare pertinent to hydrogen gas:

Hazards Present Precautions for Reducing or for Eliminating Hazards




Hazards Present

The greatest hazard that is associated with hydrogen (H2) gas is a gas explosion. Undernormal operating conditions, hydrogen accumulation in the battery room is not substantial andis not a major concern; however, during a battery charge, the battery-charging currentgenerates H2 gas at a rate that can produce explosive hydrogen-air mixtures. Hydrogenconcentrations become flammable when the concentration in air is between 4% and 79% ofthe total battery room air volume. The hydrogen-gas air mixture is considered explosivewhen the hydrogen that is in the air exceeds 4% by volume. This 4% quantity is the LowerExplosive Limit (LEL) value. A properly designed ventilation system will provide asufficient number of air changes per hour to keep the hydrogen concentration below 2% ofthe total volume of the battery room.

In addition to the release of hydrogen gas, some batteries may release small quantities of toxicgases, such as stibine and arsine. Stibine and arsine are formed when the metals antimonyand arsenic come in contact with hydrogen during a battery overcharge condition. Antimonyand arsenic are commonly used in lead-acid batteries to strengthen the plate material and toreduce plate corrosion. Although the conditions that produce these toxic gases are rare, theElectrical Engineer must be aware that these conditions do exist. Because these gases are notmonitored, maintenance of proper ventilation of the battery room is imperative.

Good engineering design practices indicate that the ventilation that is required to maintainhydrogen concentrations below the 20% LEL (approximately 1% hydrogen) also will keepstibine and arsine below their toxic limits; therefore, if the ventilation system is correctly sizedto prevent a hydrogen explosion, the threat of toxic poisoning from stibine and arsine is alsoeliminated.


Hydrogen fires and explosions can be prevented through adequate battery room ventilationand through minimization of ignition sources. Hydrogen buildup is prevented by a wellventilated battery room. Ignition sources (such as smoking, open flames, and maintenancefunctions) that are capable of producing an open arc must be eliminated.

A defective battery charger can cause excess hydrogen levels. If the charger malfunctions,excessively high battery charge rate can result. These high charge rates can producesubstantial volumes of hydrogen. Adequate, periodic maintenance testing of the batterycharger will reduce the possibility of such an overcharge condition.




BATTERY SYSTEM START-UP AND COMMISSIONING

This section of the Module will discuss the following topics that are pertinent to batterysystem start-up and commissioning:

Pre-Startup and Commissioning Checks/Verification Initial Electrolyte Filling Initial Charging Procedures Cell Voltage and Specific Gravity Measurements

Pre-Startup and Commissioning Checks/Verification

Before the actual battery start-up and commissioning can begin, the Electrical Engineer mustinspect the battery equipment for proper installation, acceptable equipment conditions, andsecurity of electrical connections. The following items are to be checked and/or verified:

Verify that the battery frame is assembled in accordance with themanufacturer's recommendations and that the battery frame is securelyanchored to the floor.

Check for any nicks or chips in the battery rack acid-proof paint. Any chips ornicks must be covered with touch-up paint that is provided by the battery rackmanufacturer. If nicks or chips are not touched-up, and if corrosive electrolyteis spilled on the rack, the electrolyte will attack the exposed steel. Such attackseventually can result in a structural failure of the battery rack and a possiblebattery rack collapse.

Verify that the cells rest on plastic or wood support channels. These channelselectrically insulate the cell from the steel frame.

Inspect cells for electrolyte leakage that can occur as a result of a cracked jar ora broken seal. All damaged cells must be replaced.

Check the color change temperature sticker that is applied to the exterior ofeach cell to determine whether the cell temperature has exceeded 45oC. Ifcolor changes are observed, the affected cells must be replaced.

Verify that the flame arrestor or the explosion-resistant vent caps, which collectelectrolyte spray and return it to the cell, are intact and are properly installed.

Check each connection for the correct complement of fastening hardware. Anyconnections that do not comply with the manufacturer's installation instructionsmust be corrected.




Apply the correct torque to each battery connection through use of a torquewrench. The torque values must be in accordance with the manufacturer'srecommendations.

Verify that all terminal connector bolts, nuts, and washers have been coatedwith an anti-oxidant.

Use the manufacturer's test instructions to collect the field data that establishesthe initial connection resistance values of each battery post connection. Thesebaseline resistance values will be used as comparison data for futuremaintenance procedures. The Individual Cell Terminal Resistance Record isincluded in Work Aid 1.

At the completion of the intercell connections, a voltmeter should be used tocheck the polarity of the series connections. The total voltage of the seriesstring should read approximately twice the number of cells (e.g., 2 x 60 cells =120 volts). If the voltage is too low, one or more cells may be improperlyconnected. The battery string should be immediately inspected, and the faultyconnection should be corrected.

Initial Electrolyte Filling

Cells that are received from the manufacturer already may be filled with electrolyte, or theymay be in a dry charge state. The size and the weight of the cell usually determines themethod of shipment. If the received cells are filled with electrolyte, the technicians only needto verify the electrolyte level and to measure the specific gravity of the electrolyte prior to theapplication of the initial (freshening) charge. If the cells are shipped dry charged, theElectrical Engineer must direct the initial electrolyte filling process and ensure that the properelectrolyte is used. If the battery will not be placed in operation immediately after installation,the initial filling should be delayed because dry batteries can be stored for longer periods oftime than can wet batteries.

Before cells that are received in a dry-charged state are filled, a verification must beperformed to ensure that the cells are sealed and that the moisture vent cap is in place. Amissing or a broken vent cap could indicate that the cell is contaminated.

Each cell is to be filled to the correct level prior to the application of the freshening charge.The cells are to be filled with the correct electrolyte as directed by the cell manufacturer.Lead-acid cells use an electrolyte that consists of sulfuric acid and demineralized water;nickel-cadmium cells use an electrolyte that consists of potassium hydroxide anddemineralized water. Concentration levels are dictated by the cell manufacturer.




The use of demineralized or deionized water is essential to the chemical reaction within thecell. Demineralized water is to be used in order to prevent the formation of foreign mineraldeposits on the cell plates. Such deposits contaminate the cell and shorten the life of the cell.

The demineralized water is to be tested to ensure that the impurity levels do not exceed thefollowing specifications:

The water must be free from suspended matter and must be colorless whenviewed through a depth of 300 mm (12 in).

The total solids in the water must not exceed 20 parts per million (ppm).

The chloride level must not exceed 20 ppm.

Concentration levels of the following impurities must not exceed the levels thatare shown:

- Iron 10 ppm- Copper 5 ppm- Manganese 0.1 ppm- Lead 2.5 ppm- Calcium 10 ppm- Magnesium 10 ppm- Zinc 2.5 ppm

To support the required chemical reactions of a battery, the diluted solutions of sulfuric acidand demineralized water or potassium hydroxide and demineralized water must be accuratelymeasured to produce the proper mix of electrolyte. The concentration of acid in theelectrolyte is determined through measurement of the specific gravity. The specific gravity ofan electrolyte is the measure of the density of the electrolyte as compared to the density ofdemineralized water. For example, the specific gravity of demineralized water is 1.000, andthe specific gravity of sulfuric acid is 1.835. Sulfuric acid, therefore, is 1.835 times denser(heavier) than demineralized water. To obtain the proper electrolyte concentration, variousamounts of demineralized water (specific gravity 1.000) and sulfuric acid (specific gravity1.835) are mixed. Dependent on the percentage of demineralized water and acid that is used,the resultant specific gravity of the diluted sulfuric acid will be between 1.000 and 1.835.

Figure 1 shows the specific gravity of an electrolyte for various amounts of demineralizedwater and sulfuric acid. The figure illustrates that the specific gravity is lower for a highervolume of water in the electrolyte. The figure also shows that specific gravity for a smalleramount of water is much higher.




The same relationship is shown with the percentage curve. As the percentage of acid in thesolution increases, the specific gravity of the solution also increases. The exact specificgravity that is required for a given cell will be specified by the manufacturer. The specificgravity for a lead-acid battery is usually controlled in the range of 1.215 and 1.250.

Sulfuric Acid - Water ConcentrationsFigure 1

Extreme caution must be taken when the acid and demineralized water are mixed. The acidand demineralized water should be mixed before they are added to the battery cells to ensureproper mixing of the electrolyte. Proper mixing of the acid and demineralized water willminimize stratification of the acid that could damage the plates of the cell. The followingguidelines should be followed when electrolyte is mixed:

Personal protective equipment should be worn.

Eyewash stations should be readily available.

Extra water supplies should be available in case of an electrolyte spill.

The acid and demineralized water should be mixed in a properly ventilatedarea.




When electrolyte is prepared for lead-acid batteries, the sulfuric acid must beintroduced into the water.

WARNING: Reversal of the mixing technique (e.g., introduction of water intosulfuric acid will result in a violent reaction that causes acid and water to splashfrom the mixing container.

The acid should be "flowed" at a very slow pace and in small increments toallow time for the release of heat that is produced during the mixing procedure,which reduces the possibility of splashing.

For potassium hydroxide solutions, the potassium hydroxide flakes or pelletsshould be carefully and slowly added to the demineralized water. Due to theexcessive amounts of heat that are produced while potassium hydroxide isbeing mixed, field mixing is not recommended. The use of premixed solutionsis recommended.

After the proper type of electrolyte has been selected and mixed, the electrolyte can be addedto the cells. All of the electrolyte safety precautions should be followed while the cells arefilled. Each cell should initially be filled to the lower fill line because the electrolyte levelwill vary with the electrolyte temperature. The cell should be allowed to set for several hours(as recommended by the manufacturer) after the initial filling to allow time for the plates tosoak. The soak time allows the plates to absorb electrolyte and allows the temperature of theelectrolyte to stabilize.

After the soak time has elapsed, the temperature of the electrolyte should be checked.Because the expansion and contraction characteristics of the electrolyte largely depend on celldesign and on electrolyte volume, the Electrical Engineer must refer to the manufacturer'sspecifications to ensure that the electrolyte is in the proper range. For example, a storagebattery design may result in an electrolyte level charge of 1/8 of an inch for every one degreechange in electrolyte temperature. Therefore, if the temperature of the electrolyte during theinitial fill is 15oC, and if the ambient temperature of the battery room is 20oC, the electrolytelevel would be expected to rise 5/8 of an inch. This level rise would equate to 1/8 of an inchfor each one degree change in temperature. The electrolyte level should be adjusted so thatthe level is in the normal operational range when the electrolyte reaches normal operatingtemperature. The operational range is indicated on the cell with upper and lower fill lines.This operational range is provided to allow for the expansion and contraction of theelectrolyte.




Initial Charging Procedures

Initial charges are performed on batteries that have been shipped wet or that have been filledin the field. Wet cells typically are shipped in a fully charged state; however, the cells mayloose some of their charge during shipping, handling, and installation. The initial chargingprocedure (freshening charge) is performed to bring the cell up to its fully charged state. Wetcells that are not immediately placed in service are to be periodically monitored to verify thecell's state-of-charge. Measurement of the cell's state-of-charge is accomplished throughmeasurement of the specific gravity. A freshening charge must be applied to batteries thatexperience a 25 point (0.025) decrease in specific gravity. Wet cells that are not placed inservice by the installation date that is recommended by the battery manufacturer also willneed to undergo a periodic freshening charge.

Cell manufacturers recommend shelf storage durations. These shelf periods vary by the typeof cell and the electrolyte status (e.g., wet or dry charged). Cells that are received wet or cellsthat are made wet in the field may be stored; however, all wet cells must receive periodiccharges while they are in storage. Cells that are filled with electrolyte should not be stored forlong periods in an uncharged condition. The uncharged period varies between cell types.Stored lead-antimony cells require a periodic charge every three months; stored lead-calciumcells require a freshening charge every six months.

The initial charging procedures will vary dependent upon the type of battery cells. The initialcharging procedures for the following types of batteries are discussed in this section:

Lead-Antimony Batteries Lead-Calcium Batteries

Lead-Antimony Batteries

Lead-antimony batteries must receive an initial charge within three months of the date ofshipment from the manufacturer. This initial charge is called a freshening charge, a boostcharge, or a forming charge, and it is typically applied by the constant potential chargemethod. The constant potential charge method is performed through application of a constantvoltage to the battery terminals for the period of time that is specified by the manufacturer.




Figure 2 shows the voltage and the current characteristics of a cell during a constant potentialcharge. Graph (a) of Figure 2 shows the steady output of the battery charger for the durationof the charge. Graph (b) of Figure 2 shows the battery cell voltage and the battery chargecurrent for the duration of the battery charge. As shown in graph (b) of Figure 2, the cellvoltage quickly rises to the charger output voltage when the charge is started. The batterycharging current drops close to zero as the charge progresses. The freshening charge shouldcontinue at the manufacturer's specified voltage, which usually is the equalize voltage, for theperiod of time that is specified by the manufacturer to ensure that the battery cells are placedin a fully charged condition. The value of voltage that is applied to the cells and the length oftime that the voltage is applied varies from cell to cell and from manufacturer tomanufacturer.

Constant Potential ChargeFigure 2




Figure 3 shows the typical initial charge volts per cell and the charging time periods for alead-antimony battery that has a nominal specific gravity of 1.215. The initial charge voltsper cell (VPC) value that should be used for the initial charge can be calculated throughdivision of the total system voltage by the number of cells that are in series. The total systemvoltage is the maximum voltage that the connected equipment will tolerate or the maximumvoltage output capability of the battery charger, whichever value is less. The calculated initialcharge VPC then is applied by the charger for the specified period of time (minimum hours)that is shown in Figure 3.

During the initial charge, a pilot cell should be monitored to ensure that the battery electrolytetemperature does not rise above 49oC. If the pilot cell electrolyte temperature reaches 49oC,the charge must be stopped, and the batteries should be allowed to cool on open circuit. Thebattery charge should not be restarted until the pilot cell electrolyte temperature has loweredbelow 32oC.

Initial Charge Volts Per Cell(VPC)

Minimum Hours for NominalSpecific Gravity of 1.215

2.392.362.332.302.24

4060

110168210

Typical Initial Charge Values for a Lead-Antimony BatteryFigure 3




Lead-Calcium Batteries

Lead-calcium cells must receive an initial charge within six months of the date of shipmentfrom the manufacturer. The initial charge of the lead-calcium cell can be delayed longer thanthe lead-antimony cell because the lead-calcium cell has a lower self-discharge rate and,therefore, will maintain its charged state for a longer period of time.

The initial charge for a lead-calcium battery should be performed through application of aninitial charge volts per cell (VPC) that corresponds to the nominal specific gravity of thebattery. The battery manufacturer normally specifies a minimum acceptable initial chargeVPC and a nominal initial charge VPC. The initial charge can be performed at any voltagethat is within the specified range, but the preferred initial charge VPC is the nominal initialcharge VPC. The output capabilities of the battery charger or the maximum voltage that canbe applied to the connected load may prevent performance of the initial charge at the nominalinitial charge VPC. Figure 4 shows the initial charge VPC values that correspond to typicallead-calcium battery nominal specific gravities.

The duration of the initial charge for a lead-calcium battery is not fixed. The charge iscontinued until the lowest individual cell voltage value ceases to rise. After the lowestindividual cell voltage ceases to rise, the charge is maintained for an additional 24 hours.During the initial charge, the individual cell voltage values must be monitored to determinewhen the lowest individual cell voltage ceases to rise. Also, the temperature of the pilot cellsmust be monitored to ensure that the electrolyte temperature does not exceed the values thatwere previously stated for lead-antimony batteries.

Nominal Specific Gravity Initial Charge VPC

Minimum Acceptable Nominal1.1701.2101.2251.2501.2751.300

2.102.132.152.182.202.23

2.292.332.362.382.402.45

Initial Charge VPC Values for Lead-Calcium BatteriesFigure 4




Cell Voltage and Specific Gravity Measurements

Cell voltage and specific gravity measurements are performed on each cell to ensure that eachcell operates at the optimum condition. Measurement of cell voltage and specific gravity willprovide an evaluation of the static charge, which provides an indication of the cellelectro/chemical condition and battery cell capacity. The following topics will be discussed ingreater detail:

Cell Voltage Specific Gravity

Cell Voltage

Cell voltage is the electrical potential that is measured between the positive and negativeterminals. Cell voltage is measured during an open circuit (no load) condition. The recordedvoltage will be a true indication of the cell's standard potential or theoretical voltage and,when plotted on an X-Y axis graph, can be used to predict remaining battery capacity.

Theoretical voltage or standard potential is calculated from the electrode potentials (e.g.,oxidation potential of the anode and reduction potential of the cathode). Theoretical cellvoltage is a function of the anode and cathode materials, the composition of the electrolyte,and the electrolyte temperature. With the cell temperature at the normal value of 25oC, andwith the specific gravity in the normal operating range, the measured cell voltage at opencircuit is a close approximation of the theoretical voltage.

The open circuit voltage of a cell depends on the state of the static charge. Figure 5 shows atypical cell voltage curve. The curve is a plot of open-circuit voltage vs. percent of ratedcapacity. If the cell has not been charged or discharged within 24 hours, the curve is accurateto within 20%. If the cell has not been used for five days, the curve is accurate to within 5%.The measurement of the open-circuit voltage to determine the state of charge is based on therelationship between the electromotive force (open-circuit voltage) and the concentration ofthe electrolyte in the battery. Electrolyte concentration level is determined throughmeasurement of the cell specific gravity.




Open-Circuit Voltage vs. State of ChargeFigure 5

Ideally, the voltage of a new battery cell on open-circuit will approach the theoretical standardpotential. Over a period of time, the electrolyte in the battery can become contaminated, andthe battery plates will corrode and deteriorate. As a result, the cell's voltage will drop. Insome instances, the contamination can be corrected through application of one or moreequalizing charges that are followed by deep discharged cycles. If the charge/dischargecycles are successful, the battery cell's voltage will rise and approach the voltage of a newcell. If the charge/discharge cycles have no affect, as determined by an ever decreasing cellvoltage, the cell must be replaced.

Individual cell voltage readings are obtained through connection of a voltmeter across thepositive and negative terminals of the cell. This measurement can be obtained through use ofa portable voltmeter or can be observed at a permanently installed individual cell voltage(ICV) meter panel. Panelmeters provide a convenient way to check the individual cellvoltages; however, because panelmeters reflect voltage losses that result from the meter leads(interconnecting wires), mechanical connections, selector switch, and the meter, panelmetersdo not provide the most accurate indication of cell voltage. If the cell voltage that is indicatedat the panelmeter appears questionable, a calibrated portable voltmeter should be used toverify the voltage of the cell that is in question.

Each battery has several individual cell voltage ratings. These ratings reflect the electricalcondition of the cell or battery and represent the voltage condition from fully charged todischarged. The individual cell voltages of a battery will vary with the operating




environment, the state of the charge, and the type of cell composition. The following is a listof the individual cell voltage ratings for a typical lead-acid and nickel cadmium battery:

Individual Cell Voltage Lead-Acid Nickel Cadmium

Open-Circuit Voltage 2.1 1.29Nominal Voltage 2.0 1.2Working Voltage 2.0-1.8 1.25-1.10End Voltage 1.75 1.10

The open-circuit voltage is the difference in potential between the terminals of the battery cellwhen the battery circuit is open or at a no-load condition. The open-circuit voltage is thevoltage that is closest to the theoretical or standard potential of a battery cell. The nominalvoltage of a battery cell is defined as the characteristic operating voltage or the rated voltageof the cell. The nominal voltage is the value that is used to determine the total voltage of thebattery (number of battery cells multiplied by the nominal voltage). The working voltage isthe voltage that is representative of the actual operating voltage of the cell under load. Theend voltage is defined as a point along the discharge curve below which no usable energy canbe drawn for the specified application. The battery cell is then considered completelydischarged.

Through close monitoring of a battery's individual cell voltage during operation and charging,the Electrical Engineer can determine the general condition of any cell in the battery. Figure 6shows a typical cell voltage curve during a battery discharge and charge cycle.

Figure 6 also plots individual cell voltage over time for a battery discharge (time 0 to time 1)and a battery charge (time 1 to time 2).




Typical Discharge/Charge Curve of a Lead-Acid CellFigure 6

At time 0, the cell voltage is at the nominal value, 2.00 volts. As the battery discharges fromtime 0 to time 1, the cell voltage drops to its end voltage of approximately 1.75 volts. At time1, a battery charge is started and the cell voltage quickly rises above the nominal voltagevalue. The cell voltage will continue to increase until the charge is complete (time 2). Whenthe charge voltage is removed, the individual cell voltage will decrease to the nominal value.If an individual cell voltage fails to respond in a similar manner, the cell is probably defectiveand should be removed from the battery for further maintenance evaluation.




Specific Gravity

The specific gravity is a measure of the density of an electrolyte in comparison to the densityof pure water. The specific gravity of the electrolyte will vary with the state of charge as aresult of the chemical reactions that occur within the cell. This section will discuss specificgravity as it relates to a lead-acid cell.

During battery discharge, the density or weight of the electrolyte will decrease because of thedisassociation of the sulfuric acid molecules; therefore, with less sulfuric acid in the batterycells, the specific gravity of the electrolyte will decrease. During a battery charge, the sulfuricacid is recombined to increase the specific gravity.

Figure 7 shows the specific gravity of a battery for a cell discharge and a cell charge. Thespecific gravity plot overlaps the cell voltage plot that was previously described in Figure 6.

Although no values are shown for specific gravity, the graph shows the relationship of thespecific gravity to the volts per cell during a discharge/charge cycle. From time 0 to time 1, aconstant cell discharge rate will result in a linear decrease in the specific gravity. During thecharge cycle from time 1 to time 2, the specific gravity will rise to the nominal value, but therise is not linear. A rapid excursion of specific gravity occurs when the cell voltage (volts percell) rises above 2.4 volts and cell gassing occurs. Cell gassing causes turbulent electrolytemixing, which causes the rapid rise in specific gravity. The state of charge of the cell can bedetermined through use of the specific gravity plot and is considered to be the most reliableindicator of the cell's state of charge.




Typical Voltage and Specific Gravity Characteristics of a Lead-Acid CellFigure 7

The specific gravity of the electrolyte is measured with a hydrometer. The most commontype of hydrometer is the syringe type, as shown in Figure 8, view A. The hydrometerconsists of a sample holding glass tube, a rubber bulb, and a float. The float is speciallydesigned and calibrated to read the specific gravity of a solution when it is immersed in thesolution. The hydrometer float consists of a hollow glass tube with a calibrated scale axiallyimprinted along the stem of the tube. The tube is weighted at one end and is sealed at bothends. Because each hydrometer float is calibrated for a specific range of specific gravities,accurate measurements of specific gravity only can be obtained through use of the correctfloat.




Typical Hydrometer




Figure 8




To measure the specific gravity of a battery cell, electrolyte is drawn into the hydrometerholding glass tube in a sufficient quantity to cause the float to enter into suspension. Once thefloat is in suspension, the scale of the float is read at the meniscus interface of the float andthe electrolyte. Typical examples of hydrometer readings also are shown in Figure 8.

The example in view (B) shows that the float has sunk low in the electrolyte; the example inview (C) shows that the float is at a higher level in the solution. The float height differencebetween the two examples is due to the difference in the specific gravities of the sampleelectrolytes.

The specific gravity of the solution is directly read from the calibrated scale, as indicated bythe meniscus of the solution. For example, the hydrometer in view (B) indicates a specificgravity of 1150, and the hydrometer in view (C) indicates a specific gravity of 1270. Thespecific gravity readings of 1150 and 1270 are equivalent to 1.150 and 1.270 respectively butcommonly are referred to as eleven-fifty and twelve-seventy.

The following guidelines must be followed to obtain an accurate specific gravitymeasurement through use of a typical hydrometer:

The interior of the hydrometer glass sample tube and the surface of the floatmust be clean. Dirty floats cause incorrect measurements, and dirty sampletubes can obscure the float scale. To avoid these conditions, the hydrometershould be periodically inspected and, if necessary, cleaned with a mild soapsolution. All washed components should be rinsed with demineralized waterbefore the components are re-assembled.

Before the electrolyte sample that is to be read is drawn into the hydrometer,the electrolyte should be drawn into the hydrometer and then discharged intothe cell two to three times to obtain a representative sample.

Sufficient electrolyte must be drawn into the hydrometer in order to cause thecalibrated tube to float in the electrolyte. The float must not touch the top orthe bottom of the sample tube and it must remain relatively free of the sampletube sides.

Specific gravity readings should be obtained before water is added to the cell.If water has been added, the hydrometer readings should be delayed untilcompletion of an equalizing charge or until the electrolyte has had anopportunity to mix for at least one hour.

The meniscus/scale interface should be held at eye level in order to preventreading the float scale in parallax.




At the completion of the measurement, all of the electrolyte should be returnedto the cell from which it was removed.

Before the hydrometer is placed in storage, it should be flushed withdemineralized water.

Because the measured value of specific gravity changes as the temperature and the level ofthe electrolyte changes, the measured values must be corrected to obtain the actual values.Figure 9 illustrates the change in the measured value of specific gravity with a change in cellelectrolyte temperature.

Specific Gravity vs. TemperatureFigure 9

As the temperature of the electrolyte increases, the following changes occur to the electrolyte:

The density of the electrolyte decreases, as measured by the hydrometer.

The volume of electrolyte increases (i.e., the level of electrolyte increases).




The ratio of the weight of acid to the weight of water for a specific volumedecreases; therefore, the measured specific gravity decreases.

Conversely, as the electrolyte temperature decreases, the measured specific gravity increases.Because the temperature only affects the value of specific gravity that is measured by thehydrometer and not the actual value of available acid, the measured value must be corrected.This compensation correction will adjust all specific gravity readings to a standardtemperature (25oC). Adjustment of the readings for the temperature will provide accuratespecific gravity readings. These readings will then permit accurate comparisons betweencells.

The following guidelines are used to adjust the specific gravity readings to a standardtemperature of 25oC:

Add one point (.001) to the specific gravity reading for every 1.67oC that theelectrolyte temperature is above the 25oC standard.

Subtract one point (.001) from the specific gravity reading for every 1.67oCthat the electrolyte temperature is below the 25oC standard.

A change in electrolyte level also will affect the measured value of specific gravity. Thischange is due to the change in concentration of the acid and the water in the electrolyte.Electrolyte levels can change for the following reasons:

Evaporation Leakage Spillage of electrolyte during sampling Extreme temperature changes Addition of water to the cell

The actual change in specific gravity that occurs as a result of electrolyte level changes willvary with the size of the battery and the electrolyte concentrations. In some installations, achange in level can have a negligible effect on the specific gravity as long as the electrolyteremains in the normal range. In other installations, the change in electrolyte level can besignificant. The manufacturer's technical literature must be consulted to obtain the electrolytelevel correction factor for each particular battery.

The expected specific gravity readings of a cell will depend on the type of cell, the type ofelectrolyte, and the state of charge of the cell. Typical specific gravity readings for a lead-acid and a nickel-cadmium cell are provided in Figure 10.




The readings reflect various states of charge that range from a fully discharged battery to afully charged battery. The values that are provided in Figure 10 are representative of thevalues that would be measured during a battery discharge at a constant discharge rate. Abattery that is being charged or that is being heavily discharged will not produce accuratespecific gravity readings. As previously shown in Figure 7, the specific gravity will linearlydecrease during a battery discharge; however, during a charge, the specific gravity rises in anon-linear fashion.

Typical Specific Gravity ReadingsFigure 10




UPS SYSTEM START-UP AND COMMISSIONING

The start-up and commissioning procedure of a UPS system consists of a series of systemchecks and tests that are performed in coordination with the manufacturer. The testingmethods and the procedural steps to perform the start-up and commissioning will be providedby the equipment manufacturer and will be approved by Saudi Aramco. The resultant dataare to be recorded on the Start-Up and Commissioning Test Results Data Sheet. This sectionwill provide information on the following topics that are pertinent to UPS system start-up andcommissioning:

Verifying Proper Electrical Connections Verifying Initial System Set-Up Simulation of Line Power Source Loss

Verifying Proper Electrical Connections

The purposes for verifying proper electrical connections during start-up and commissioningof a UPS system are the following: to confirm that no loose connections exist that could arcand present a hazard to personnel; and to verify that the interconnecting wiring is correct (toavoid possible damage to the system equipment).

The electrical equipment of a UPS system should not be energized until all electricalconnections have been visually inspected. The visual inspection should include but shouldnot be limited to the following:

Verify that all electrical components are installed in accordance with the designdocuments.

Verify that all field wiring has been installed in accordance with the projectelectrical drawings.

Check all electrical terminations, field connections, and vendor equipment fortightness.

Check electrical conductor insulation for any breaks, voids, or signs ofmaterials stress.

Verify that electrical conductors are free of any sharp edges or moving partsthat will damage the insulation.




Verifying Initial System Set-Up

The initial system set-up will verify all of the operational functions of the UPS system. Thesystem set-up will include the following areas:

Initial Conditions System Setpoints Calibration Checks Switching Functions

Initial Conditions

The Electrical Engineer must verify that all the UPS system manufacturer's technical manualshave been received and that these manuals apply to the specific installation. Many of themanufacturer's technical manuals are equipment specific, and a non-applicable manual cancreate major problems.

The Electrical Engineer must verify that all overcurrent protection fuses have been installedand are of the correct value. If the fuses are undersized, they can unnecessarily trip. If thefuses are oversized, they may permit excessive current flows that can result in possibledamage to the equipment.

A check of the available incoming power sources also is an initial condition requirement.These incoming power sources consist of a preferred ac power source that normally connectsto the inverter circuit and an alternate ac power source that connects to the static switch andthe manual bypass switch. Some installations may further segregate the power through use ofa third incoming ac power source that would connect to the manual bypass switch. In thiscase, the alternate ac power source would supply only the static switch.

The Electrical Engineer must verify that the inverter and the battery charger enclosureventilation fans properly operate. An inoperable fan or a restricted air flow can produceexcessive temperature in the interior of the enclosure. These excessive temperatures cancause operational failures and premature electrical component failures.




System Setpoints

System setpoints consist of two types: alarm and control. The purpose for verifying alarmsetpoints during UPS system start-up and commissioning is to check the alarm points of themonitored parameters. The alarm points monitor selects system parameters and will "alarm"when a parameter is reached or exceeded. Operating in the extremes of these maximum andminimum parameters is conducive to component/system failure. The control setpoints areused to establish the nominal UPS system operating conditions. An initial check of thesecontrol setpoints is necessary to establish functionality and a point of control, as well as toestablish baseline conditions.

Alarm Setpoints - Each UPS system is provided with a number of alarm points. Theparameters that are to be monitored are dependent on the installation and designrequirements. Saudi Aramco design specifications and manufacturer suggestions willdetermine which of the system parameters will be monitored by an alarm circuit.Procedural steps for testing each alarm point are provided in the manufacturer'stechnical manual. The following is a list of the alarms that are associated with atypical UPS system:

dc Input Voltage High Alarm dc Input Voltage Low Alarm Alternate Voltage/Sync Source Not Available Alarm Static Switch Position Indication Alarm Output Failure Alarm Enclosure Overtemperature Alarm

The dc Input Voltage High Alarm indicates the point at which the dc input to theinverter has reached or exceeded a specified maximum operating condition. The alarmsetpoint is adjustable and should be set at a value of +5.0% of the nominal dc inputvoltage.

The dc Input Voltage Low Alarm indicates the point at which the dc input to theinverter has reached or exceeded a specified minimum operating condition. The alarmsetpoint is adjustable and should be set at a value of -5.0% of the nominal dc inputvoltage.

The Alternate Voltage/Sync Source Not Available alarm will actuate when thealternate power source voltage is not available at the static switch. If the alternatepower source is not available, and if an inverter failure occurs, power to the criticalload will be lost. The alternate power source is considered "not available" when thevoltage deviates from the nominal system voltage by +/- 10% or when the frequencydeviates from the nominal system frequency by +/- 5%.




The Static Switch Position Indicator alarm will energize when the static switchtransfers from the inverter to the alternate power source. This alarm, as a result of thestatic switch transfer, indirectly indicates that the inverter has failed; therefore, thesubject alarm should be accompanied by an Inverter Output Failure Alarm.

The Inverter Output Failure Alarm will warn of a loss of inverter output power. Thisalarm occurs if the output voltage deviates outside of the range of +/- 10% or if thefrequency deviates more than +/- 5.0% of the nominal 60 Hz value.

The Enclosure Overtemperature alarm warns that the inverter equipment is operatingat above the normal temperature. Overheated inverter electrical components can resultin abnormal output voltage and frequency conditions. Continuous overheating of theelectrical components may result in a premature equipment failure.

Control Setpoints - A UPS system is to provide pure, fully conditioned power to thecritical loads. This power is to be controlled and regulated within specific conditions.Setpoint adjustments are provided to achieve this required regulation and control. Theregulation and control adjustments are as follows:

Output Voltage Output Frequency Phase Relationship Waveform Purity and Harmonic Distortion Level Static Switch Transfer/Re-Transfer Voltage Monitor Static Switch Transfer/Re-Transfer Frequency Monitor Battery Isolation Circuit breaker Shunt Trip

Output Voltage - The general requirements of a UPS system are that the voltage outputfrom the static inverter must be at the design nominal voltage +/- 10%, at a frequencyof 60 Hz +/- 5.0%, and in-phase with the ac source voltage. The input to the staticinverter can be from the stationary battery or from the output of the battery charger,and the input must be verified before adjustment of the static inverter output voltage.The purpose for verifying the output voltage adjustment during UPS system start-upand commissioning is to ascertain that the inverter is producing an output voltage thatis within acceptable tolerance. Typically, the battery output and the battery chargeroutput voltage should be in the range of +/- 10% of the dc nominal voltage.




If the battery output voltage is not within specification, the individual cell voltages andthe specific gravities should be checked, and the battery should be charged. If thebattery output voltage does not return to the normal range, additional batterytroubleshooting should be performed. If the battery charger output voltage is withinthe proper range, the static inverter voltage can be adjusted on the inverter's internalcontrol module. If the battery charger output voltage is not within the range of +/-1.0% of nominal value, the battery charger output voltage should be adjusted.

The static inverter's output voltage is adjusted through a variance in the delay time orfiring angle of the SCRs. The output voltage should be adjusted when no load isapplied to the static inverter. This adjustment procedure is accomplished throughinstallation of a portable voltmeter on the inverter output. While the portable testmeter is being monitored, the output voltage control that is located on the inverterelectronic control board is adjusted to set the output voltage to the nominal value.After all of the voltage adjustments have been made, the output voltage should berechecked with the static inverter connected to the critical ac loads. Under electricalload, the output voltage again should be monitored for voltage level abnormaltransients and waveform purity. Adjustment to the firing angle of the SCRs affectsonly the magnitude of the voltage and does not directly affect the frequency or thephase angle of the output voltage.

Output Frequency - After the input voltage has been adjusted, the frequency of theoutput voltage should be checked. If the output from the static inverter is not at 60 Hz,the transfer from the preferred source to the alternate will not be a smooth transfer.The output frequency from the static inverter should be monitored with theac source reference deenergized or disconnected. Deenergization of the ac sourcevoltage will ensure that the static inverter is not synchronized with an external sourcethat may prevent adjustment of the static inverter output frequency. A convenientmethod to monitor the static inverter output is with an oscilloscope. The oscilloscopeshould indicate a 16.7 millisecond period for one complete cycle. If the frequency isnot at 60 Hz, the frequency can be adjusted on the static inverter's oscillator board.

Phase Relationship - When the static inverter's output voltage and frequency are withinspecification, the phase relation between the inverter output and the ac line should bechecked. This relationship easily can be seen on a dual trace oscilloscope. The phaserelationship between the two sources should be zero and can be adjusted on thesynchronizing board of the static inverter.




Static Switch Transfer/Re-Transfer Voltage Monitor - The electronic circuit of the staticswitch monitors the inverter output voltage. If the output voltage fluctuates outside therange of +/- 10% of the nominal inverter output voltage, the static switch willimmediately transfer (less than 4.2 milliseconds) to the alternate source. The staticswitch will remain in the diverted or alternate position until the following conditionsare satisfied:

Inverter output voltage returns to within +/- 2.0% of nominal output voltage.

Inverter and alternate source are phase-synchronized.

The above two conditions have been maintained for a duration of at least 30seconds before re-transfer is permitted.

At this time, the static switch will transfer back to the inverter (preferred) source.

Static Switch Transfer/Re-Transfer Frequency Monitor - The electronic circuit of the staticswitch also monitors the inverter output frequency. If the output frequency fluctuatesoutside the range of 60 Hz (+/- 5.0%), the static switch will immediately transfer (lessthan 4.2 milliseconds) to the alternate source. The static switch will remain in thediverted or alternate position until the following conditions are satisfied:

Inverter output frequency returns to 60 Hz (+/- 2.0%).

The above frequency value has been maintained for a duration of at least 30seconds before re-transfer is permitted.

Battery Isolation Circuit Breaker Shunt Trip - A two pole circuit breaker is installed in thedc circuit ahead of the inverter. This breaker is designed to "trip" in the event of a lowdc voltage. A shunt trip circuit in the breaker monitors the dc voltage. If the dcvoltage to the inverter exceeds the -10% range of the nominal dc voltage, the shunt tripmonitoring circuit will energize to trip the breaker in order to protect the battery fromdischarging below the final battery voltage. (For the final battery voltage value, theequipment manufacturer's technical manual is to be consulted.)

Waveform Purity and Harmonic Distortion Level - The waveform of the static inverteroutput should be monitored on start-up to ensure that the inverter can produce anoutput that is comparable to the manufacturer's specifications. Although absolutelimits on the waveform distortion do not exist, the measured waveform should modelthe waveforms that are supplied by the manufacturer. The inverter output should bechecked with a spectrum analyzer for harmonic distortion. Harmonic distortion that isgreater than 4% can cause problems with electronic equipment. If harmonic distortionexceeds the maximum allowable level of 4%, the equipment manufacturer should becontacted.




Calibration Checks

Part of the set-up and commissioning of the UPS system, in addition to checking andestablishing alarm and control setpoints, is to verify that the panelmeters are accurate. Thepanelmeters provide a convenient means to monitor the important system parameters. Thepanelmeters provide a continuous indication of the monitored parameters. The readingsobtained from panelmeters are to be within +/- 2.0% of the readings that are obtained with acalibrated test instrument.

Switching Functions

The majority of UPS systems have a manual bypass switch. The manual bypass switch isused during the performance of maintenance and testing functions. Three-phase (3_) systemsalso employ panelmeter selector switches. This section provides information on the followingtopics that are pertinent to switching functions:

Manual Bypass Switch Panelmeter Selector Switches

Manual Bypass Switch - The manual bypass switch provides a method to connect thecritical ac loads directly to a reliable source of power with no downtime of the loads.The inverter then can be isolated for safe inspection, testing, and maintenance. Two-way bypass switches perform the following functions:

To shunt the power potential around the inverter without interrupting theinverter output power. Flow of current divides between the bypass switchcontacts and the inverter to ensure that not even a momentary interruption ofpower to the critical loads occurs in the event of an inverter failure.

To allow the inverter to be electrically tested and adjusted without interruptingor affecting power to the critical load. The inverter output is disconnected fromthe critical load, but the inverter is still energized from the normal andemergency sources and can be electrically tested without affecting the criticalload.

To electrically isolate the inverter from the preferred and alternate source ofpower and from the critical load in order to permit inspections and maintenanceof the inverter. In this position, the inverter is completely isolated while thecritical load continues to be fed through the bypass contact.




Panelmeter Selector Switches (3_ Systems) - Selector switches, when used in conjunctionwith a panelmeter, allow individual three-phase parameters to be monitored with onemeter. In systems that do not require simultaneous continuous monitoring of theparameters, the use of a single meter and a selector switch is more economical.Selector switches are provided to monitor the following parameters:

Voltage - Switch positions: A-B, B-C, A-C, L-N Frequency - Switch Positions: A_, B_, C_, L-N Amperage - Switch Positions: A_, B_, C_

Simulation of Line Power Source Loss

The purpose of simulating a line power source loss is to verify that a UPS system willproperly operate under the designed conditions to provide an uninterrupted, bumpless transferto the alternate source of power.

Two conditions must be observed to ensure the proper operation of the UPS system: thetransfer of power from the preferred power source to the alternate power source and thetransfer of power from the alternate source to the preferred source.

The following sequence of events should be observed during the performance of thesimulated line power source loss test:

When the UPS system is in automatic, and when the preferred source of power(output of the inverter for a reverse transfer scheme) is available, the inverteroutput supplies power to the critical load. In this situation, the input to theinverter can be the ac preferred source via the battery charger or the stationarybattery.

If any of the following conditions occur, a transfer signal will be generated anda transfer will occur:

- The inverter output voltage goes outside of the normal range (i.e., _10% of the nominal voltage).

- The inverter output frequency goes outside of the normal range (i.e.,_5% of the nominal frequency).

- An external transfer signal, such as the inverter in the current limit modeof operation, is present.




A line power source loss can be simulated through performance of one of thefollowing actions:

- Open the dc input breaker to the inverter.

- Open the ac input breaker to the battery charger and open the batteryoutput breaker.

- Open the battery output breaker and, through use of a variable ac inputsource, vary the ac voltage outside of the normal range.

If a transfer inhibit signal is not present, the transfer to the alternate source willoccur. If a transfer inhibit signal is present, the transfer will be blocked and thecorresponding alarm will occur. The following are examples of conditions thatwill result in a transfer inhibit signal and a blocked transfer:

- The alternate power source voltage is outside of the normal range (i.e.,_10% of the nominal voltage).

- The alternate power source frequency is outside of the normal range(i.e., 60 Hz _5% of the nominal frequency).

- An external transfer inhibit signal, such as a sync disconnect signal, ispresent.

The ac alternate source will continue to supply power to the critical loads untilthe external transfer signal is removed from the preferred source sensing circuitand the following conditions are met:

- The inverter output voltage returns to _2% of the nominal voltage andremains at this value for at least 30 seconds.

- The inverter output frequency returns to _2% of the nominal frequencyand remains at this value for at least 30 seconds.

When the above conditions have been met, the critical load will be transferredto the inverter output, which is the preferred source of power.




INTERPRETING START-UP AND COMMISSIONING TEST RESULTS

A major function of the Electrical Engineer during the course of a battery and UPSinstallation is to monitor and to direct the actions of the maintenance personnel. After theinstallation, and prior to placement of the equipment in service, the Electrical Engineer has anequally important role to monitor and to analyze the results of the installation tests andinspections. Through an analysis of the results of the tests and inspections, the ElectricalEngineer can determine whether the battery and UPS system installation is acceptable or candetermine what must be done to make the installation acceptable.

This section will cover the following topics that are pertinent to interpretation of start-up andcommissioning test results:

Battery System Start-Up and Commissioning Battery Charging Start-Up and Commissioning UPS System Start-Up and Commissioning

Battery System Start-Up and Commissioning

The determination of the acceptability of the battery system relies on the following items:

The completeness of the battery tests and inspections. The accuracy of the battery system test data. The correct interpretation of the battery system test data.

The completeness of the tests and inspections is primarily fixed by the data sheets that areprovided to the Engineer from Saudi Aramco and the battery manufacturer. Although theElectrical Engineer may specify additional tests for the battery, the start-up andcommissioning tests that are presented in this Module normally are more than adequate toprovide the information that is needed to commission a battery.

The accuracy of the battery test data depends on the qualifications and experience of themaintenance staff and on the application of the test equipment. Interpretation of this datamust be performed by an Electrical Engineer who is familiar with normal and abnormalconditions that pertain to battery systems.

To begin the interpretation of the results of battery system start-up and commissioning, theElectrical Engineer will require the following data sheets:

DC/UPS System Start-up and Commissioning Test Results Data Sheet Individual Cell Terminal Resistance Test Record Battery Test Record Battery Acceptance Test Data Sheet




These data sheets are provided in Work Aid 1.

The DC/UPS System Start-Up and Commissioning Test Results Data Sheet (Figure 16 ofWork Aid 1) is divided into four sections:

Pre-Commissioning Checks Battery System Checks Battery Charger Setpoints and Calibration Checks UPS System Checks and Setpoints

The Pre-Commissioning Checks section of the data sheet applies to the Battery Charger andUPS system as well as the battery system. The Battery Charger data and the UPS system datawill be discussed later in this Module.

The Pre-Commissioning Checks section and the Battery System Checks section of theDC/UPS System Start-up and Commissioning Test Results Data Sheet should be checked toensure that data have been recorded in all of the blanks and that the data sheet has beenproperly signed and dated. The Remarks section should be checked for any notedabnormalities.

The Electrical Engineer also should verify that the Individual Cell Terminal Resistance TestRecord, the Battery Test Record, and the Battery Acceptance Test Data Sheet have beenproperly completed and are included in the review package.

Before the battery system equipment data are analyzed, the Electrical Engineer must verifythe satisfactory completion of the Pre-Commissioning Checks. Any abnormalities oroperational conditions that are outside of the nominal operational range for the battery canaffect the outcome of the remainder of the data that were collected. If the Electrical Engineerdetermines that one or more of the pre-commissioning checks is unsatisfactory, he mustdetermine whether this unsatisfactory condition impacts the validity of the remainder of theresults. If the Electrical Engineer determines that the validity of the remainder of the results isaffected, he should ensure that the unsatisfactory condition is corrected and that the affectedstart-up and commissioning tests are performed again.

The Battery System Checks section of the DC/UPS System Start-Up and Commissioning TestResults Data Sheet (Figure 16 of Work Aid 1) consists of seven items that must be verified.Verification of each item is to be performed in accordance with the procedure and theacceptance criteria that are located in Work Aid 1.

The first test results to be reviewed are the Individual Cell Terminal Resistance Test Record(Figure 17 of Work Aid 1). If the terminal resistances are high, they will reduce the outputvoltage of the battery. Resistance values that do not meet the acceptance criteria that arelocated in Work Aid 1 must be corrected before the startup and commissioning evaluation iscontinued.




After verification of satisfactory cell terminal resistances, the Electrical Engineer shouldreview the Battery Test Record results. The following data on the Battery Test Record(Figure 18 of Work Aid 1) should be analyzed for each cell:

Individual cell voltage Specific gravity (temperature corrected to 25oC)

The individual cell voltage should be within the range that is specified by the acceptancecriteria that are located in Work Aid 1. The individual cell voltages also should be checked incomparison to the other cells of the battery to ensure that the maximum deviation between thecell voltages does not exceed the values that are specified in Work Aid 1. Any deviation thatis outside of these normal cell voltages indicates a problem with the battery cell and willaffect the overall efficiency of the battery. The individual cell voltages can be offspecification for a number of reasons. The following is a partial list of these reasons:

An improper charge on the battery cell. A poor intercell connection. An improper reading by the maintenance staff. A defective cell.

If the individual cell voltage is off specification, the individual cell voltage should be taken asecond time to determine whether the initial reading was accurate. If the reading wasaccurate, the torque and the resistance of the affected intercell connections should berechecked, and the battery should be recharged with the proper charging procedure. In anycase, the manufacturer's technical literature should be consulted for additional troubleshootingsteps and for additional corrective actions.

The temperature-corrected specific gravity for each cell should be within the range that isspecified by the acceptance criteria that are located in Work Aid 1. The specific gravity alsoshould be checked in comparison to the other cells of the battery to ensure that the maximumdeviation between the specific gravities does not exceed the values that are specified in WorkAid 1. Any deviation that is outside of these normal specific gravity readings indicates aproblem with the battery cell and will affect the overall efficiency of the battery. The specificgravity readings can be off specification for a number of reasons. The following is a partiallist of the reasons:

An improper charge on the battery cell. An improper reading by the maintenance staff. An improper temperature correction was applied. An incorrect hydrometer was used. The readings were taken after the battery was watered. The cell is defective.




If the specific gravity is off specification, the specific gravity should be taken a second time todetermine whether the initial reading was accurate. If the reading was accurate, thetemperature correction calculation should be rechecked; the equipment that was used to makethe measurement should be checked to ensure that it is the correct equipment; and, if required,the battery should be recharged with the proper charging procedure. In any case, themanufacturer's technical literature should be consulted for additional troubleshooting stepsand for additional corrective actions.

Individual cells that do not meet the acceptance criteria should be replaced, and the batteryshould be recharged in accordance with the manufacturer's recommended chargingprocedures.

After completion of the verification of the Battery Test Results, the Electrical Engineer shouldreview the Battery Acceptance Test Data Sheet (Figure 19 of Work Aid 1). The batteryacceptance test results should indicate that the battery can sustain a specific discharge rate fora specified time duration in accordance with the manufacturer's rating. The discharge rateshould be a constant current load that is equal to the manufacturer's rating of the battery forthe selected test length. The selected test length should be the time that the battery is requiredto supply the critical loads.

Battery Charger Start-Up and Commissioning

The ability to determine the acceptability of a battery charger relies on the following:

The completeness of the battery charger tests and inspections. The accuracy of the battery charger test data. The correct interpretation of the battery charger test data.

The completeness of the tests and inspections is primarily fixed by the data sheets that areprovided to the Engineer from Saudi Aramco and the battery charger manufacturer. Althoughthe Electrical Engineer may specify additional tests for the battery charger, the start-up andcommissioning tests that are presented in this Module normally are more than adequate toprovide the information that is needed to commission a battery charger.

The accuracy of the battery charger test data is dependent on the qualifications and experienceof the maintenance staff and on the application of the test equipment. Interpretation of thisdata must be performed by an Electrical Engineer who is familiar with normal and abnormalconditions that pertain to battery chargers.




At the start of the verification of the start-up and commissioning test results, the ElectricalEngineer must check to see that data are recorded in all of the line items that are shown in thebattery charger section of the DC/UPS System Start-Up and Commissioning Test ResultsData Sheet. The Remarks section also should be checked for any abnormalities.Abnormalities or operational conditions that are outside the nominal operational range for thebattery charger can affect the validity of the collected data. The Electrical Engineer mustdetermine whether any abnormal conditions exist. If such conditions do exist, the ElectricalEngineer must determine whether the condition has an effect on the validity of the collecteddata. If the Electrical Engineer determines that an abnormal condition does affect the validityof the collected data, the Electrical Engineer should have the abnormal condition correctedand should have the affected tests performed again before the start-up and commissioningevaluation is continued.

The data that are recorded in the Battery Charger Setpoints and Calibration Checks sectionshould be interpreted through use of steps 3a through 3k of the procedure and acceptancecriteria that are located in Work Aid 1.

UPS System Start-Up and Commissioning

The ability to determine the acceptability of a UPS system relies on the following:

The completeness of the UPS system tests and inspections. The accuracy of the UPS system test data. The correct interpretation of the UPS system test data.

The completeness of the tests and inspections is primarily fixed by the data sheets that areprovided to the Engineer from Saudi Aramco and the UPS system manufacturer. Althoughthe Electrical Engineer may specify additional tests for the UPS system, the start-up andcommissioning tests that are presented in this Module normally are more than adequate toprovide the information that is needed to commission a UPS system.

The accuracy of the UPS system test data are dependent on the qualifications and experienceof the maintenance staff and the application of the test equipment. Interpretation of this datamust be performed by an Electrical Engineer who is familiar with the normal and theabnormal conditions that pertain to UPS systems.




At the start of the verification of the start-up and commissioning test results, the ElectricalEngineer must check to see that data are recorded in all of the line items that are shown in theUPS system section of the DC/UPS System Start-Up and Commissioning Test Results DataSheet. The Remarks section also should be checked for any abnormalities. Abnormalities oroperational conditions that are outside of the nominal operational range for the UPS systemcan affect the validity of the collected data. The Electrical Engineer must determine whetherany abnormal conditions exist. If such conditions do exist, the Electrical Engineer mustdetermine whether the condition has an effect on the validity of the collected data. If theElectrical Engineer determines that an abnormal condition does effect the validity of thecollected data, the Engineer should have the abnormal condition corrected and should havethe affected tests performed again before the start-up and commissioning evaluation iscontinued.

The data that are recorded in the UPS System Checks and Setpoints sections should beinterpreted through use of steps 4g through 4x of the procedure and the acceptance criteriathat are located in Work Aid 1.




WORK AID 1: PROCEDURES AND CRITERIA FROM SADP-P-103, IEEE 446,AND ESTABLISHED ENGIN

Commissioning of DC & UPS Systems

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