3 Phase Instruction Manual

7/30/2019 3 Phase Instruction Manual

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Th ree Ph ase Pad M ou n tedTh ree Ph ase Pad M ou n ted

D istr ib u tion Transfo rm ersD istr ib u tion Transform ers

General Instruction sfor Installation andOperation

ERMCO Dist ribut ion Transform ers

P. O. Box 1228, Dyersburg, TN 38025-1228

Ph o n e : 7 31 -2 8 5 -9 1 21

Fax : 731-287-4104

Date: Febru ary, 2003

In struct io n M anu al #103In struct io n M anu al #103

ERMCO


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INTRODUCTION

This instruction manual provides generalinformation for the installation, operation, andmaintenance of ERMCO three phase, padmounted transformers. These units are

designed for outdoor installation on flat, levelpads or foundations. All high voltage and lowvoltage cables are installed through an openingin the pad beneath the cable terminationcompartment. The compartment is designed forpadlocking and has barriers to resist tamperingand vandalism.

These transformers are to be applied and usedper the "usual service conditions" described in

ANSI C57.12.00 (General Requirements forLiquid-Immersed Distribution, Power andRegulation Transformers).

RECEIVING AND INSPECTION

ERMCO pad mounted transformers are shippedfilled with insulating transformer oil. Immediatelyupon receipt, and before being put into service,transformers should be carefully inspected forany external damage or loose parts caused byshipping and handling. Damage presumed tohave occurred during shipment should be noted,and your ERMCO sales representativecontacted.

Each unit has been carefully assembled and

inspected at the factory. Extreme care has beentaken in the processing and sealing of thetransformer to insure that it is clean and dry, andof adequate dielectric strength. Therefore, it isnot recommended that the transformer seals bebroken. If it is decided, however, that thetransformer be opened, adequate precautionsshould be taken as outlined in the next sectionof the instructions.

HANDLING AND INSTALLATION

Transformers should only be lifted using all four

lifting provisions installed on the transformer.The transformer must never be moved or liftedby any means other than the lifting provisionsprovided for that purpose. Care must be taken toavoid excessive horizontal force during lifting.Cable pull angles should not exceed 30 fromvertical or a spreader bar should be used to holdthe lifting cables in a vertical position. Do notuse jacks or tackles under cooling panels, ifsupplied. Jacks should only be placed under the

jack pads provided on the tank. The unit may beskidded in both directions. With the sill anddoors in place, the unit may be rolled in bothdirections using rolling bars. The cablecompartment sill may be unbolted and removed.The cable compartment may be removed by

lifting the side door out of the hinges where it isattached to the tank front plate. The cablecompartment hood can be tilted back forimproved access to the tank front plate. Forbest results and assurance of proper electricalinsulation to ground, the transformer shouldalways be installed and maintained on a flat,level surface while energized. The transformerto pad interface should not have gaps, whichcould defeat the tamper-resistance of thetransformer.

Insure that all hardware removed duringinstallation is securely replaced in order toeliminate any openings into the cabinet or anyother potentially energized area of thetransformer. Check to make sure that anyprotective barriers are securely in place, thecabinet is completely closed and lockingprovisions are installed before leaving thetransformer site unattended. ERMCO takes noresponsibility for damages due to improperinstallation. The customer is solely responsiblefor completing all installation work in a goodworkmanship manner and within industrystandards.

TANK COVER REMOVAL

Do not open the transformer tank unlessabsolutely necessary. Clean the area aroundthe entrance cover before opening thetransformer and exposing the internalmaterials to the atmosphere. Keep moistureand foreign debris out of the tank.

The transformer must be de-energized,grounded, and disconnected before opening.The transformer will have a bolted on tankcover which must be removed to gain access

to the internals. To remove the tank cover,begin by opening the terminal compartmentto expose the front cover nuts. Removethese nuts to allow removal of the covertamper guard. Finally, remove the nutsholding the tank cover in place and lift thecover vertically to prevent damage to thecover, gasket, or fasteners.


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OIL

Transformers are thoroughly dried at the factoryand filled with ERMCO inhibited mineral oilhaving a minimum dielectric strength of 30 kV at60 Hz when tested per ASTM D-877. ERMCO

inhibited mineral oil contains less than 1 ppm ofPCB's at time of manufacture. The transformershould never be energized unless it is filled withoil. If it should be found necessary to add to orreplace the oil in the transformer, use clean, dryoil only, having a minimum dielectric strength of30 kV and less than 1 ppm PCB's. Beforeopening the transformer, sufficient time shouldbe allowed for the transformer to come totemperature equilibrium with the air in the roomto eliminate the possibility of moisturecondensation from the air.

To check oil level or to add oil, first bring theinterior of the transformer to atmosphericpressure by venting the automatic pressurerelief valve furnished on all ERMCOtransformers. Then, remove the oil level pluglocated on the tank front plate which is locatedat the 25C oil level. If it is necessary to add oil,it may be added through the oil level plug.

A natural rubber hose should not be used inthe transfer of oil.

To lower the insulating oil for maintenance orinspection:

1. Start with a clean dry container to store thetransformer oil.

2. Use clean pumps and hoses that will notcontaminate the oil. Do not use naturalrubber hoses.

3. Attach the pump intake line to the drainvalve on the transformer.

4. Place the output line on the bottom of thestorage container. Do not permit the oil tosplash into the container as this mayintroduce air and moisture into the oil.

5. Do not lower the oil below the top of thecore clamp. Exposing the coil and

insulation to the atmosphere will allow airbubbles to become trapped in the insulationand could lead to insulation failure.

To replace the oil in the transformer:1. Pump from the bottom of the storage

container. Do not allow the intake line tosuck air.

2. To prevent aeration at the outfeed, direct theoil stream parallel to and along the uppersurface of the core clamp.

3. Pump slowly and fill the tank to the 25Cline.

4. Allow several hours between refilling and

energization of the transformer to be surethat any gas bubbles created during theprocess have been dissipated.

To Sample the transformer oil:1. Samples should be taken only after the oil

has settled which can be several days forlarge transformers or in cold climates.

2. Oil samples should be taken from thesampling valve at the bottom of the tank.

3. Start with a clean dry bottle to store thetransformer oil.

4. Sample the oil only when the transformer iswarmer than the surrounding air to avoidcondensation of moisture on the oil.

5. Draw out sufficient oil to fill the bottle threeor four times. Discard this oil according toproper environmental requirements. Retainthe oil from the final draw in the bottle as thetest sample.

CONNECTIONS

Refer to the transformer nameplate for the kVArating and the permissible connections. Noconnections other than those shown on the

nameplate should be made; and none of theconnections should be changed while voltage isapplied to the transformer.

For low voltage connections, the loads betweenthe line terminals and neutral should be asnearly equal as possible. More than one-halfthe rated kVA should not be applied betweenany one line terminal and neutral.

Provisions are made for grounding the tank bymeans of tapped pads and ground connectors, ifordered.

GROUNDED-WYE TRANSFORMERS

Grounded-wye pad transformers normally haveone end of the high voltage winding brought outthrough insulated bushings and the other end ofthe winding connected internally to the tank. Asubstantial and thoroughly reliable groundconnection should be made between the tank


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and low resistance ground through a conductorof adequate cross section. One or moreexternal grounding pads are provided on thetank front plate of the unit. It is imperative thatboth the tank (and the low voltage neutral if it isgrounded-wye) be solidly and permanently

grounded to the common neutral of the systembefore the transformer is energized. If this is notdone, a high voltage may be impressed betweenthe low voltage circuit and ground constituting ahazard to life and property. The safestprocedure is to first make the groundconnections, then the low voltage lines, andfinally the high voltage connections. When thetransformer is removed from service, all highvoltage connections (including those toprotective devices) should be opened first.

PRIMARY TERMINATIONS

Dead front Transformer Connections: Primaryterminations are made with shielded separableinsulated cable elbow connectors, used withexternally clamped bushing wells. Loadbreak ornon-loadbreak bushing inserts should be usedwith the wells, unless integrated bushings arefurnished.

Bushings are provided with tabs to accept a bail,used as a positive hold down for elbows. Thebail prevents accidental removal of elbowconnectors under energized conditions.

When removing cables from the bushings, theymay be easily transferred to an adjacent parkingstand. The parking stands will accept open plugtype accessories available for loop feed,grounding or insulating the terminators duringtrouble shooting, sectionalizing or maintenance.On transformers equipped with bushing wells,the bushing inserts may be changed or replacedat the installation site. Changing inserts doesnot affect the transformer seal.

SECONDARY TERMINATIONS

Low voltage bushings are externally clampedinsulators with either threaded studs or spadeterminations. With grounded-wye secondaries,the neutral terminal consists of an insulatedbushing with a ground strap connecting thebushing to ground. To avoid damaging thebushing when blade type spades are added,replaced or interchanged, first install the jam nuton the stud, hand tight. Second, install the

spade and back the jam nut against the spadewith a wrench, thus locking the nut and spadetogether on the stud.

OVERLOAD AND OVER VOLTAGEPROTECTION

Transformer protection against overloads andover voltages may be obtained by having theunit supplied with suitable devices from thefactory.

A. Bayonet Fuses

ERMCO transformers may be equipped witha bayonet type expulsion fuse. Theexternally operable bayonet fuse assemblyprovides load break capacity by simple hotstick withdrawal. Transformersincorporating this device must not be appliedto primary distribution systems where theavailable fault current will exceed themaximum current interrupting capability ofthe bayonet fuse. Where the available faultcurrent does exceed the maximum currentinterrupting capability of the fuse, currentlimiting fuses should be used.

Fuse Removal Procedure:

1. Vent transformer by opening the pressurerelief device with hot stick. Next, standing toone side of the transformer, attach hot stick

to fuse holder eye and twist hot stick tounlock fuse holder.

2. Turn fuse holder 90 in tube to break theseal between the seal gasket and the outertube assembly. NOTE: If tank pressure isnot released, fuse holder may be forcedout of transformer. Maintain control offuse holder at all times.

3. Draw the fuse holder out quickly 4 to 6inches to interrupt the load. Wait a fewmoments for the oil to drain into the tank.

4. Remove fuse holder from outer tubeassembly and wipe off fuse cartridge holderand fuse cartridge.

5. Use a wrench to remove the fuse cartridgefrom the cartridge holder.

6. Remove end plug from fuse cartridge usingtwo wrenches. Use screwdriver or other tool


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to straighten the tulip tip end of fuse elementand push fuse element out of fuse cartridge.NOTE: Replace fuse cartridge if damaged.

7. Insert replacement fuse element intocartridge from either end. Tulip tip may

have to be closed slightly to allow insertioninto cartridge.

8. Install the cartridge and fuse to the holderwith the formed end ferrule towards theholder. Secure the holder while using awrench on the flat of the cartridge ferruleand torque to 50-70 in-lbs.

9. Spread tulip tips of fuse before installing endplug. Tighten end plug to expand the tuliptips using a wrench on end plug whileholding fuse cartridge with wrench on flat offerrule next to end plug and torque to 50-70in-lbs.

10. Remove end plug and inspect the tulip tipsto see that they are uniformly expanded toinsure even contact. Replace the end plugand torque to 50-70 in-lbs.

11. Check oil level at oil fill plug, and add oil, ifnecessary.

12. Attach end of fuse holder assembly to hotstick and insert holder assembly firmly intothe outer tube assembly. Twist the locking

handle so that the latch engages the outertube shoulder. NOTE: Visually inspect innerfuse holder assembly to ensure it is installedproperly.

WARNING: The bayonet fuse is notrecommended for fault closing. Seriouspersonal injury may result if attempted.Internal fault conditions can cause thetransformer to rupture. Always energizetransformer from remote location to besafe. This device was designed andintended for under oil application only.

Refer to Step 11. for correct oil level.

CAUTION: Do not re-energize suspectedfailed transformer. When replacing ablown fuse, the feed circuit should beopened and closed from a remotelocation. After fuse replacement, thebayonet should be replaced using theprocedure described above andre-energized from a remote location. If

equipment is re-fused while energized,the fuse could close in on the system'smaximum fault current. Any equipmentthat has a suspected failure should notbe closed in with this fuse. Thebayonetfuse is designed to be operated in

accordance with normal safe operatingprocedures. These instructions are notintended to supersede or replace existingsafety and operating procedures. Thebayonet fuse should be installed andserviced only by personnel familiar withgood safety practices and the handling ofhigh voltage electrical equipment.

B. Internal Expulsion Fuses

Some ERMCO transformers may beequipped with internal expulsion fuses thatcannot be replaced. The fuse is in serieswith the HV winding, and in case of internalfailure of the transformer or overload, theprotective link disconnects the transformerfrom the line without affecting line fuses orbreakers.

Internal expulsion fuses should not be usedon primary distribution systems where theavailable fault current exceeds the maximumcurrent interrupting capability of the fuseelement. Where the available fault currentdoes exceed the maximum currentinterrupting capability of the fuse, current

limiting fuses should be used.

C. Internal Current Limiting Fuse

ERMCO transformers are also available withinternal current limiting fuses that will limitthe energy let through into the fault.

D. Dry-Well Current Limiting Fuse

The transformer may be supplied with a dry,current limiting fuse holder and full rangecurrent limiting fuse. Fuse holder types may

be non-loadbreak or loadbreak. Consult thelabels on the transformer front plate near thefuse holders for instructions on removal ofthe fuse. The transformer must be de-energized before attempting removal of anon-loadbreak dry well fuse holder.


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E. Lightning Arresters

Some transformers are supplied withinternal under-oil lightning arresters. Thesearresters are permanently connected intothe transformer circuit. A disconnect switch

may be supplied with the transformer toallow the lightning arresters to be removedfrom the circuit for testing purposes. Thisswitch is not rated for load break application.Follow the instructions on the label suppliednext to the switch for proper operation.Elbow type lightning arresters may beapplied to ERMCO transformers by the end-user.

F. Secondary Breakers

Some ERMCO transformers are protectedagainst secondary overloads and shortcircuits by an internally mounted circuitbreaker. The function of the breaker is toopen the low voltage circuit and protect thetransformer from faults or severe overloads.

The breaker operating mechanism isdesigned to be operated by a lineman's hotstick. Transformers are shipped with thecircuit breaker in the closed position.

To open the breaker manually, move thehandle fully counterclockwise so that thepointer moves from the "C" (closed) to "O"

(open), at which point the circuit is open.Verify that the circuit breaker is latched inthe "open" position. To ensure thedischarge of the static charge, which issometimes present in the low voltagewinding due to capacitance, it isrecommended that the low voltage begrounded after opening the circuit breakeruntil after the high voltage is disconnected.

To close the breaker, rotate the handle fullycounterclockwise to "R" (reset), whichengages the latch mechanism, and then

clockwise to "C" (closed). If a fault exists oran excessive load exists at the time thebreaker is closed, the breaker will reopeneven though the handle is held in the "C"(closed) position.

Some circuit breakers are equipped with anemergency overload device that can beused to restore service following a circuitbreaker operation due to overload. The

emergency overload lever is locatedimmediately above the breaker operatinghandle. With the emergency lever in thenormal position, the breaker will trip at itsnormal setting as calibrated at the factory.Moving the lever in a clockwise direction

increases the setting so a highertemperature is required to trip the breaker.The emergency setting may be adjusted toan intermediate or extreme value. Thisemergency setting provides extra loadcapacity and still permits manual breakeroperation, and also retains short circuitprotection of the transformer. It is importantthat the emergency setting be used onlywhen, and as long as, absolutely necessarybecause its use will result in a reduction oftransformer life.

A meter seal is provided on the emergencylever to prevent tampering. It isrecommended that a new seal be installedon the lever when it is returned to the normalposition after emergency operation.

The breaker is a thermal and short circuitprotective device for the transformer. It isnot recommended that the breaker be usedfor routine disconnect operations.

SWITCHING DEVICES

Dual Voltage and Taps:

ERMCO transformers rated for more than oneprimary voltage are equipped with a dual voltageswitch and/or tap changer. These switches areexternally operated, but should never beoperated while the transformer is energized.When switching from one voltage to another,make sure the switch is in the proper positionbefore re-energizing the transformer. Afterturning the switch, tighten the locking device tominimize the possibility of unintentionalmovement. Units equipped with dual voltageand tap changer switches should be operated

with extreme caution. Taps should only bechanged when dual voltage switch is set inthe series (higher) voltage position,otherwise serious damage to the transformercould result.

Internal Loadbreak Switches:

Internal loadbreak switches may be suppliedwith the transformer. These switches are


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designed to interrupt rated current only and theyare not designed to interrupt fault currents.Consult the labels on the transformer front platenear the switch for instructions on operating theswitch.

GASKETS

Bushing gaskets are all made of Buna-N Nitrilerubber. Gaskets may be reused if not damaged.STORAGE

Transformers should be stored filled with oil andin a clean dry place. If possible they should bestored where there will be no extremetemperature changes. Before the transformer isput in service, it should be checked in the samemanner as when received.

MAINTENANCE

A periodic visual inspection of the transformer isrecommended. At such times, the generalcondition of the following should be noted.

1. High voltage bushings;2. Low voltage bushings;3. Arresters (if provided);4. Enclosure integrity (hinges, locking

provisions, corrosion, etc.);5. Evidence of oil leakage;

6. Ground connections;7. Accessories;8. Safety labels;9. Transformer tilt.

Where tanks show evidence of rusting ordeterioration of the finish, they may be cleanedand then retouched with paint. It is necessary toremove all loose paint and rust by wire brushing,scraping, or sanding. Clean the surface using agood solvent. Apply an acrylic lacquer, alkydenamel, two part urethane, or a silicone alkydprimer, allow to dry, and then apply a color

matched, compatible top coat and allow to dry.

If metal is rusted to the point of being weak suchthat the enclosure integrity can be compromised,repair or replace the part rather than painting it.

REPLACEMENT PARTS

Replacement parts are available from ERMCO.When ordering parts, give a complete

description of the part. Also, give the kVA,voltage, and serial number of the transformer, allof which may be found on the nameplate.

ADDITIONAL INFORMATION

Complete information on details of construction,installation, operation and maintenance can beobtained from the ERMCO factory or yourERMCO Sales representative.


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ERMCODistribution Transformers & Components

16 25 Sylvan RoadP.O. Box 1 22 8Dyersbu rg, TN 3 8025

.

Pho ne: 731 .285 .912 1Fax: 731.287.4104W eb Site: w w w .ermco -eci.com

3 Phase Instruction Manual

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