Cu0114 WP Electricity for Hospitals v2

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APPLICATION NOTE

ELECTRICITY SYSTEMS FOR HOSPITALS

Angelo Baggini

June 2014

ECI Publication No Cu0114

Available from www.leonardo-energy.org



Publication No Cu0114

Issue Date: June 2014

Page i

Document Issue Control Sheet

Document Title: Application Note – Electricity Systems for Hospitals

Publication No: Cu0114

Issue: 03

Release: June 2014

Author(s): Angelo Baggini

Reviewer(s): Bruno De Wachter, Roman Targosz, Noel Montrucchio (English)

Document History

Issue Date Purpose

1 March

2011

Initial release

2 November

2011

Adapted for the Good Practice Guide

3 June 2014 Revision

Disclaimer

While this publication has been prepared with care, European Copper Institute and other contributors provide

no warranty with regards to the content and shall not be liable for any direct, incidental or consequential

damages that may result from the use of the information or the data contained.

Copyright© European Copper Institute.

Reproduction is authorised providing the material is unabridged and the source is acknowledged.





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CONTENTS

Summary ........................................................................................................................................................ 1

The Basic Electrical Installation ....................................................................................................................... 2

Safety and Reliability .............................................................................................................................................. 2

Ensuring safety: standard IEC 60364-7-710 ............................................................................................. 2

Ensuring reliability ............................................................................................................. ....................... 6

Functional earthing .................................................................................................................................. 7

Equipment specifications ......................................................................................................................... 8

Protection against lightning ..................................................................................................................... 8

Power Quality ............................................................................ .............................................................. ............... 9

Causes of power quality problems ............................................................................................... ............ 9

Solutions ........................................................... ................................................................. ..................... 10

Energy Efficiency ........................................................................................................ ........................................... 14

Electrical network ........................................................ ................................................................. .......... 14

Lighting ............................................................. ................................................................. ..................... 14

Technical condition monitoring and energy management ............................................................. ..................... 16

Other Important Issues Concerning the Medical Electrical System ............... ...................................................... 17

HVAC ........................................................................................................................................................ 18

Indoor Air Quality (IAQ) ........................................................................................................ ................................ 18

Reliability versus Energy Efficiency .......................................................................................................... ............. 18

Energy efficiency in Steam and hot water production ........................................................................... 18

Heat recuperation .................................................................................................................................. 18

Co-generation .............................................................. ................................................................. .......... 19

Motor system efficiency ......................................................... .............................................................. .. 19

Compressed air ............................................................................................................................................. 21

Medical and Technical Compressed Air ................................................................................................... ............. 21

Energy Efficiency of Compressed Air ............................................................................................... ..................... 21

Auxiliary Systems .......................................................................................................................................... 22

Conventional Building Automation Systems ........................................................................................................ 22

Patient Assistance and Telemedicine ................................................................................... ................................ 22

Hospital Communication Systems ........................................................ .............................................................. .. 22

Conclusions ................................................................................................................................................... 23





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References .................................................................................................................................................... 24





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SUMMARY

Given that the core business of a hospital is the welfare of its patients, it is easy to understand why the

intricacies of electricity are not a high priority. However, ensuring patient welfare requires a huge variety of

medical appliances, which in turn, require electricity. Electricity is therefore a vital utility and any malfunction

or interruption can quickly lead to disastrous consequences.

This combination—being absolutely vital but far from the primary concern of the organization—entails a

certain risk.

Standards and regulations prescribe how a hospital’s electrical installations should be conceived and installed

to ensure safety and reliability. Those regulations are complemented by the prescriptions of the equipment

manufacturers. All these rules, however, create a complex tangle of information for the user, often making it

difficult to figure out which rule has to be applied where and exactly how it has to be implemented. In this

tutorial, we will try to shed light on those regulations and give a comprehensive overview. Once safety and

reliability are taken care of, the focus can shift to energy efficiency. The fact that efficiency is only of secondary

priority for a hospitals’ electrical installation does not mean its impact cannot be significant. By focusing onenergy efficiency, hospitals can often make surprisingly large savings on the total cost of ownership (TCO) of

their installations and thus on the cost of the medical aid they render. This paper addresses a few of the major

energy efficiency topics relevant to medical building management.





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THE BASIC ELECTRICAL INSTALLATION

SAFETY AND RELIABILITY

There are several reasons why electrical safety and reliability is of uttermost importance for medical facilities.

These include among others:

- Electromagnetic Compatibility: The high density of electric and electronic equipment in medical

premises involves a risk on electromagnetic disturbances between the electricity supply and medical

devices.

- Criticality of continuity: Many medical treatments cannot be interrupted even for a moment without

entailing risk for patient and on occasion, life-threatening risk.

- Data integrity: Accurate medical data is essential and are often gathered by long-term or invasive

patient examination.

- Leakage currents: Currents leaking from various devices may be individually safe but combined with

others can add up quickly and exceed the safe level.

- Weak or sensitive patients: Some patients have weakened or non-existing reflexes in the event of

direct contact with live electrical parts. Other patients may have reduced skin resistance because of

stress, sweating, or catheters/electrodes introduced on or into the body.

ENSURING SAFETY: STANDARD IEC 60364-7-710

All low voltage electrical installations must comply with IEC 60364, the general international standard for

electrical safety. In particular, Section 710 of this standard is dedicated to medical locations and prescribe

certain additional requirements for such locations. It is included in the seventh part of IEC 60364, hence the

code IEC 60364-7-710. Most national regulations on electrical safety in medical facilities are derived from IEC

60364-7-710. It applies to hospitals, medical clinics (including the self-contained type), medical and dental

surgical facilities, dedicated rooms in nursing homes where patients are given medical treatment, rooms for

physiotherapy, beauty centers, ambulatory and emergency aid units in industrial or sport facilities and

veterinary surgeries. It is primarily a safety standard, as well as providing some rules on ensuring availability

(see further).

Standard IEC 60364-7-710 categorizes all medical rooms into three groups, based primarily upon the use of

applied parts. An applied part is any part of an electro-medical device that might come into contact with a

patient. Each group has a dedicated set of protective measures.

Group 2 includes all rooms where the loss of power supply may endanger the patient ’s life. It also includes all

medical locations in which applied parts are used for intra-cardiac procedures (risk of micro-shock to cardiac

muscles). Finally, it includes all rooms related to operations involving general anesthesia: pre-operation rooms,

operating theaters, surgical plaster rooms, and post-operative recovery rooms. The measures for Group 2

include:

Protection against direct contact through proper insulation

No power interruption is allowed (for medical equipment nor for support services such as lighting)

An IT earthing system to protect against earth faults (avoiding power interruptions)

Group 1 includes all medical locations that do not belong to Group 2 and where applied parts are used,

externally or invasively. Examples are rooms serving for physiotherapy or hydrotherapy, and dental surgery.

The measures for Group 1 include:





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Protection against direct contact through proper insulation

In case of a power interruption, crucial support services such as lighting should switch to an

alternative power supply

A TNS earthing system is permitted

Group 0 includes all medical locations where no applied parts are used, such as outpatient rooms, massagerooms without electro-medical devices, offices, store rooms, canteens, changing rooms, corridors, staff

hygiene facilities, waiting rooms, et cetera. No extra measures have to be taken for Group 0 other than those

general prescriptions for electrical safety in buildings (Standard IEC 60364). Nevertheless, a high level of

electrical reliability and safety should be maintained. This means that power quality disturbances (e.g.

harmonic distortion, stray currents, et cetera), electric faults, and equipment damage (e.g. neutral conductor

interruption, insulation degradation, et cetera) should be avoided. If a TN or TT earthing system is being used,

it is advisable to continuously monitor the insulation quality by a Residual Current Monitor (RCM). This device

should not be confused with a Residual Current Device (RCD). The RCM monitor can never disconnect the

circuit, but rather continuously monitors the differential current value and sends alarm signals if thresholds are

exceeded. This enables taking predictive measures and avoiding unexpected failures. Such monitoring can also

be a first step in improving the energy efficiency of the system.

Qualified medical personnel must carry out the assignment of the rooms to one of these three groups. If no

such personnel are available, the national healthcare organization must be called in.

The function of a particular room is often changed during the lifetime of a hospital; for instance because of

changed needs. It can therefore be wise to equip certain rooms for a higher group classification than their

initial use demands. Those rooms will then be upgradable without significant costs for the electrical

installation.

PROTECTION AGAINST DIRECT CONTACT (GROUPS 1 AND 2)

Direct contact means a person touches a live part of the electrical system. Indirect contact means a persontouches a conductive (metal) part which is normally not live, but which has become live due to a fault in the

electrical insulation.

Protection against direct contact is straightforward. All live parts must have a proper electrical insulation,

barrier, or casing. The insulation protection level should be the stringent IPXXD (IP4X automatically guarantees

the protection level IPXXD) for horizontal surfaces within reach, and the slightly less stringent IPXXB (IP2X

automatically guarantees the protection level IPXXB) in all other cases.

PROTECTION AGAINST INDIRECT CONTACT THROUGH AUTOMATIC CIRCUIT BREAKING (GROUP 1)

The Standard IEC 60364-7-710 specifies that the protection must be compatible with the earth connection

method used by the network.

In the situation where a TN earthing connection method is used, an automatic miniature circuit breaker is

sufficient, but a Residual Current Device (RCD) is advisable. The RCD reaction times must be as follows:

Voltage phase-earth Reaction time

terminal circuits

Reaction time

distribution circuits

120 V 0.4 s 5 s

230 V 0.2 s 5 s

400 V 0.06 s 5 s





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In case a TT earthing connection system is used, the use of a Residual Current Device is mandatory, for which

the following formula must be satisfied:

RE · Idn ≤ 25

In which:

RE = earth resistance of earth plate (ohm)

Idn = maximum rated residual current (amperes)

In addition to the above, the standard specifies that an RCD with a rated residual current ≤ 30 mA is

mandatory for:

Group 1 locations: terminal circuits that supply sockets outlets with a rated current of up to 32 A

Group 2 locations: all circuits that are not powered by a Medical IT System (see further), unless they

are supplying fixed devices which are positioned at least 2.5 m above the floor and which cannot

enter the patient’s environment.

Figure 1 – The space around a patient in which an RCD with a rated residual current ≤ 30 mA is mandatory.

Note that for any medical location:

The protection device should bring the possible contact voltage in the event of an incident below 25

V. (Whereas the maximum contact voltage for non-medical locations is 50 V.)

The type of Residual Current Device (AC, A or B) should correspond with the type of devices in the

network to ensure its proper functioning. In the event a TN earth connection method is used, the TN-S variant should be used downstream of

the main distribution switchboard.

PROTECTION AGAINST INDIRECT CONTACT THROUGH MEDICAL IT SYSTEM (GROUP 2)

This shall be applied to all circuits in Group 2 medical locations supplying:

Medical equipment located at less than 2.5 meter from the walking surface, or which could enter the

patient’s environment

Socket outlets (except for radiological devices and those powering devices of more than 5 kVA)

A Medical IT System guarantees the continuity of power supply to critical medical operations after a first earth

fault, while at the same time ensuring protection against indirect contact. This is made possible thanks to a





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medical insulating transformer , which galvanically separates a terminal circuit from the rest of the electrical

system.

Insulation transformers exist with a power of 3.5 kVA, 5 kVA, 7.5 kVA, and 10 kVA. As transformers have a long

life span (several decades), it is better to over-estimate the power load to enable future extension without the

need to exchange the transformer. Specifications for the medical insulating transformer are given in StandardIEC 60364-7-710.

Should a second earth fault in another part or device occur, the medical insulation transformer can no longer

guarantee the safety and proper functioning of the system. For this reason, the Medical IT System should

contain a device for permanent earth insulation resistance monitoring.

This device will give an alarm (alarm light plus acoustic signal) when a first earth fault occurs, so that the

required measures can be taken to rectify it as soon as possible. The monitoring device itself can be placed

inside the electrical switchboard of the medical IT system (see further), but the acoustic and optical signals

must be placed at a location with continuous presence of qualified healthcare personnel. Specifications for the

insulation monitoring device are given in Standard IEC 61557-8.

The medical IT system should be connected to a separate switchboard , or to a separate section in the main

switchboard. It should have an ordinary power supply as well as an emergency power supply (see further). The

switchboard of the medical IT system typically contains the following: the insulating transformer, an insulating

monitoring device for the 230 V circuit, an insulating monitoring device of the 24 V circuit, a transformer

230/24 V – 1 kVA, a surge arrester, and a temperature probe PT100.

The circuits of the medical IT system are preferably installed in separate cable ways (pipes, ducts, boxes). In

the event that ducts or boxes are shared with other circuits, an insulation barrier should be installed between

both circuits. In any case, Group 2 medical locations can never contain cable ways supplying power to other

locations. In Group 2 medical locations, all conductors should be shielded . Ducts should be protected by

omnipolar automatic miniature circuit breakers. Moreover, circuits of medical IT systems should be protected

with fuses or thermomagnetic automatic miniature circuit breakers.

Group 2 circuits should be monitored as intensively as possible. For example, conductors and windings should

have temperature monitoring. The monitoring data and alarm signals after exceeding threshold values should

be properly prioritized and managed by qualified technical or medical personnel that can react immediately

and appropriately.

PROTECTION THROUGH CLASS II DEVICES

Class II medical electrical equipment has a double insulation, avoiding any risk of persons touching a

conductive part. In Group 0 and Group 1 locations, these devices do not need to be connected to equipotential

bonding and to the earth. In Group 2 locations, however, Class II medical devices must be connected to the

local equipotential bus bar.

PROTECTION THROUGH SYSTEMS WITH VERY LOW SAFETY V OLTAGE (SELV AND PELV)

Protection against both direct and indirect contact can also be acquired by reducing the voltage of the circuit

to maximum 25 V (alternating current) or 60 V (non-inverted direct current). This concept is known as Safety

Extra Low Voltage (SELV) or Protection Extra Low Voltage (PELV). The power is then supplied through a safety

transformer or a battery. The circuits must be installed according to the Standard IEC 60364-4 (clause 411.1).

The active parts must be insulated with a protection level IP XXD for horizontal surfaces within reach, and with

a level IP XXB for all other active parts.

In Group 2 locations, the safety transformer must be powered by the insulation transformer of the medical IT

system. Moreover, all devices must be connected to the local equipotential bus bar.





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SELV and PELV systems are rarely used, except for particular equipment such as scialytic devices and infusion

pumps.

SUPPLEMENTARY EQUIPOTENTIAL BONDING

Applicable for all Group 1 and Group 2 locations.

Equipotential bonding is the connection of all conductive parts of the electrical system and conductive parts

extraneous to the electrical system with each other, and subsequently connecting this bonding network to the

earthing network. Extraneous conductive parts include, for instance, metal pipes, metal window frames, and

iron components of reinforced concrete. Equipotential bonding avoids the situation that two metal parts could

hold a different electrical potential, entailing the risk of electrocution if they were to be touched

simultaneously.

The general standard on electrical safety in buildings prescribes equipotential bonding for all rooms with a

bath or shower.

Standard IEC 60364-7-710 regarding medical locations obliges the equipotential bonding of all conductive

parts extraneous to the electrical system that are entering the same building.

Moreover, Standard IEC 60364-7-710 requires supplementary equipotential bonding for all Group 1 and Group

2 locations. These rooms must be equipped with their own equipotential bonding bus bar to which all electrical

devices and all extraneous conductive parts are connected.

For Group 2 locations, the electrical resistance between the (extraneous) conductive part and the bus bar shall

not exceed 0.2 Ω. Every conductive part should be connected separately to this bus bar without any additional

sub-node, with the only exception being metal pipes and nearby sockets. The local bus bar can be placed on a

wall inside the location or immediately outside the room. If the Group 1 or 2 locations should contain a bath or

shower, the metal parts of these installations must be connected to the bus bar as well. The cables used for

the equipotential bonding network must have minimum cross sections as prescribed by the standard. The bus

bar must be easy to access for inspection. It must be possible to disconnect each of the conductors from the

bus bar, and all cables of the equipotential bonding network must be clearly identifiable.

ENSURING RELIABILITY

The first category of measures providing a high reliability of power supply is those ensuring the selectivity of

the electrical protections. A protection has a high selectivity if it only disconnects these circuits where the

safety problem occurs, leaving the power supply to the other circuits intact. Horizontal selectivity is achieved

by subdividing the system into many different circuits with each having a separate protection. For Group 2

rooms and Medical IT systems, IEC 60364-7-710 prescribes a separate protection for each group of plugs.

Vertical selectivity is achieved by ensuring that downstream protections trip before the upstream protections.

For example, downstream automatic circuit breakers should have a lower trip current than the upstream

automatic circuit breakers. In the case of RCDs or circuit breakers, the upstream protection should trip with a

time delay relative to the downstream protections.

A second category of reliability measures are those ensuring the availability of power supply in the event of

blackouts or power interruptions. Although primarily a safety standard, IEC 60364-7-710 also prescribes

certain rules regarding this.

Those rules define, for a certain category of devices:

In which circumstances the emergency power supply should connect

The maximum time delay in which the emergency power supply should connect (e.g. after maximum

0.5 s)





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The minimum time duration the emergency power supply should be able to serve all vital appliances

(e.g. minimum 24 h)

A first category concerns all Group 2 locations and Group 1 appliances considered medically critical, for which

the most stringent rules should be applied. For example, the reaction time of emergency lighting above a

surgery table should be ≤ 0.5 s.

A second category includes all other electro-medical devices.

A third category includes all other equipment that is necessary for maintaining hospital services.

The IEC 60364-7-710 standard also includes rules on safety lighting. Safety lighting is obliged on the following

locations:

Group 1 and Group 2 medical locations

Exit routes and safety exits, including the associated safety signs

Rooms containing electrical cabinets, electrical switchboards, or generation sets

Rooms providing essential services, such as elevator motors, kitchens, air conditioning stations, data

processing centers, et cetera

In the event of a power interruption, safety lighting must be switched to an emergency power supply in ≤0.5 s

for lighting devices with a life support function and in ≤15 s for all other safety lighting devices. Emergency

power can be supplied in the same way as for the other safety devices (see further), or by individual batteries

for each device with an autonomy of at least 2 hours.

These IEC standards are complemented by the general European Standard EN 8-38 on emergency lighting in

public buildings.

The emergency power can be provided in different ways . For low power (typically under 400 kVA), a staticUninterruptable Power Supply (UPS) will be used. This is a device that can provide near-instantaneous power

by means of batteries and associated electronic circuitry. However, it has a limited autonomy (10 to 30 min)

and must therefore be combined with a generator set (GenSet) for acquiring the required levels of autonomy.

For higher power rates (typically ≥ 400 kVA), a dynamic UPS can be used. This device integrates the UPS

function with a diesel generator of flywheel for longer autonomy.

In each case, emergency power should be provided by at least two UPS devices supplying 50% or less of their

maximum power. In this way, overload problems are avoided and one UPS can stand in if the other one

malfunctions or drops out.

The type and size of the emergency power systems must be chosen with accuracy and according to case

specific criteria. Moreover, buying the right device alone does not suffice; you have to ensure it will always

operate as expected. It is therefore essential that the emergency power supply is installed by qualified

experts and that its performance is tested on a regular base. As testing procedures are not included in the IEC

standard, it is recommended that the prescriptions from manufacturers be followed. Some EU countries have

a national law on mandatory periodic testing of emergency power supply systems (e.g. Italy).

FUNCTIONAL EARTHING

The earthing of electrical devices and conductive parts is not only necessary for safety reasons, but also to

ensure the proper functioning of the equipment. All electric and electronic devices send out electro-magnetic

signals, which may disturb other devices. Preventing such disturbances is called functional earthing or ensuring

Electro-Magnetical Compatibility (EMC). Functional earthing is not included in the hospitals’ Standard IEC60364-7-710, but in another section of the same general standard (i.e. IEC 60364-7-707). To ensure EMC, a





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classical connection to the earth is not sufficient. Designing an earthing network that filters out all mutual

disturbances is a complex task, to be executed by a specialized engineer.

EQUIPMENT SPECIFICATIONS

Standard IEC 60364-7-710 contains some limited prescriptions on the electrical safety of medical devices.

More extensive prescriptions for medical electrical equipment are listed in a series of standards with numberIEC 60601-xx.

In addition to these prescriptions, the technical specifications of equipment manufacturers sometimes

mention EMC guidelines for their devices. Useful as that may be, an earthing network should always be

designed from a system’s perspective, and not from the perspective of a single device. Moreover, equipment

specifications tend to focus on functional earthing alone, without taking electrical safety into account. In some

cases, functional earthing and earthing for safety reasons can come into conflict with each other. It is therefore

important to leave the design of the earthing network to a specialized engineer who can guarantee both EMC

and electrical safety.

PROTECTION AGAINST LIGHTNING Protection against lightning strikes is included in the general safety Standard IEC 62-305. Two different risks

have to be evaluated: the risk of losing a human life, and the risk of material damage and its corresponding

financial losses.

According to the IEC standard, the former risk should be no higher than one loss of life out of 100,000 direct

lightning strikes on the building. The standard proposes clear protection measures to reduce this risk.

Concerning the latter, the IEC standard only provides an assessment method for evaluating the financial risk.

Having this assessment at hand, it is up to the users to decide how much they want to invest in additional

protective measures.





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POWER Q UALITY

Reliability of electricity supply is the only Power Quality criterion that is included in the standards dedicated to

electrical installations in hospitals. However, other Power Quality criteria should also be taken into account in

the design of the system to avoid the malfunction of medical and other equipment.

An ideal electrical power supply is always available, always within voltage and frequency tolerances, and has a

pure noise free sinusoidal wave shape. How much deviation from perfection can be tolerated depends upon

the application, the type of equipment installed, and its requirements.

Making an abstraction of supply interruptions, which have already been discussed in the paragraph on

reliability, power quality issues fall into the following categories:

Harmonic distortion

Voltage variations

Flicker

Overvoltages and transients

Unbalance

Each of these problems has a different cause. Some have their origin in shared infrastructure. For example, a

problem on one customer’s site may cause a transient that affects all other users on the same subsystem of

the public network. Other problems, such as harmonics, arise within the customer’s own installation and may

or may not propagate onto the public network and therefore affect other customers. Harmonic problems can

be dealt with by a combination of good design practice and well-proven reduction equipment.

Ensuring good power quality requires good initial design, effective correction equipment, cooperation with the

supplier, frequent monitoring, and good maintenance. In other words, it requires a holistic approach and a

thorough understanding of the principles and practice of power quality improvement.

CAUSES OF POWER QUALITY PROBLEMS

X-ray based devices, MRI systems, CT scanners, and linear accelerators typically absorb currents with high crest

factor and very steep wave fronts (see Figure 2). This behavior can cause voltage sags and other electrical

disturbances in the installation. X-ray based devices in particular are a major source of electrical pollution. The

same equipment is also very sensitive to voltage variations.

The problem of sensitivity to electrical disturbances is common to almost every electronic medical device. In

addition, the immunity to power quality issues of most of these devices is generally low and very often

unknown.

Figure 2 – Oscilloscope screenshot of the mains electrical behavior during angiography showing sinusoidal

voltage and distorted currents.





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In general, the causes of Power Quality problems in hospitals can be listed as follows:

HARMONICS

In hospitals, harmonic currents are typically caused by electronic loads. In recent years, the types of hospital

equipment causing harmonics have risen sharply, as well as the number of units. This number will continue to

rise, so designers and specification writers must now consider harmonics and their side effects very carefully.One of the major issues related to harmonic currents is the overload of neutral conductors because of triple-n

harmonics.

VOLTAGE DIPS AND SWELLS

Voltage dips primarily originate from large loads and/or from faults on other branches of the public

distribution network. Voltage sags—longer-term reductions in voltage—are usually caused by a deliberate

reduction of voltage by the supplier to reduce the load at times of maximum demand or by an unusually weak

supply in relation to the load.

TRANSIENTS, SURGES

The causes of voltage transients and surges include the switching of equipment or lightning strikes on theelectricity supply network, and the switching of reactive loads on the hospital’s site itself or on nearby sites on

the same line.

FLICKER

Flicker is a general term for short-term voltage changes. They result from switching actions, short-circuits, and

load changes.

UNBALANCE

As a practical matter, the asymmetry of the load connected to each of the three phases is the main cause of

unbalance.

At high and medium voltage level, the loads are usually three-phase and balanced.

Low voltage loads are usually single-phase, e.g. PCs or lighting systems, and the balance between phases is

therefore difficult to guarantee. In the layout of an electrical wiring system, the load circuits are distributed

amongst the three phases. Still, the instantaneous balance fluctuates because the duty cycles of the individual

loads differ.

Abnormal system conditions also can cause phase unbalance. Phase-to-ground, phase-to-phase, and open-

conductor faults are typical examples. These faults cause voltage drops in one or more of the phases involved

and may even indirectly cause overvoltages on the other phases. The system behavior is then unbalanced by

definition, but such phenomena are usually classified under voltage disturbances (discussed in the

corresponding application guides). In such a case, the electricity grid’s protection system should cut off the

fault.

LONG TERM UNDERVOLTAGES AND OVERVOLTAGES

Long-term undervoltages or overvoltages may be caused by load variations, system switching operations, and

general system voltage regulation practices.

SOLUTIONS

PQ should always be a point of concern when purchasing, installing and maintaining medical equipment.

However, maintaining good PQ is a cooperative effort between healthcare facilities, equipment vendors,

equipment manufacturers, and electricity supply companies.





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Even though manufacturers are presently introducing new devices with input capacitor filters to mitigate

power quality deviations, this is often not enough. A systems approach has to be adopted.

Many power quality problems could be avoided if (1) the quality of power at the point of use is known, (2) the

equipment immunity is known, and (3) the immunity is sufficiently high.

A large variety of solutions are now available on the market and the major portion of the power quality

problems can be avoided with the appropriate adoption of specific system characteristics and/or power-

conditioning devices. The opportunity to adopt each of the corrective measures listed hereunder is dependent

upon the specific situation, the immunity level of the equipment, and the level of power quality disturbances.

DISTRIBUTION SCHEME

A simple but effective approach to achieve good PQ is to separate the supply of sensitive loads from the supply

of disturbing loads. Depending on the level of disturbances and the level of immunity, the separation can vary

from the level of the final circuits, up to the level of entire distribution networks.

UNINTERRUPTIBLE POWER SUPPLY SYSTEMS (UPS)

UPS systems are now commonly used as standby power supplies for critical loads for which the transfer time

to the standby supply must be very short or zero. Static UPS systems are readily available in ratings from 200

VA to 50 kVA (single-phase) and from 10 kVA up to about 4000 kVA (three-phase). As well as providing a

standby supply in the event of an outage, UPSs are also used to improve local power quality. The efficiency of

UPS devices is high, with energy losses ranging from 3% to 10%, depending on the number of converters used

and the type of secondary battery.

The basic classification of UPS systems is given in the Standard IEC 62040-3 published in 1999 and adopted by

CENELEC as Standard EN-50091-3 [1]. The standard distinguishes three classes of UPS, indicating the

dependence of the output voltage and output frequency upon the input parameters:

VFD (output Voltage and Frequency Dependent upon mains supply)

VI (output Voltage Independent of mains supply)

VFI (output Voltage and Frequency Independent of mains supply)

DYNAMIC VOLTAGE RESTORERS

Where heavy loads or deep dips are concerned, a Dynamic Voltage Restorer (DVR) is used. This device is series

coupled to the load and generates the missing part of the supply. If the voltage dips to 70%, the DVR generates

the missing 30%. DVRs are normally expected to support the load for a short period and may use heavy-duty

batteries, super capacitors, or other forms of energy storage such as high-speed flywheels. DVRs cannot be

used to correct long-term undervoltages or overvoltages.

PASSIVE FILTERS

Passive filters are used to provide a low impedance path for harmonic currents so that they flow into the filter

instead of into the supply. The filter may be designed for a single harmonic or for a broadband spectrum,

depending on the requirements.

Simple series band stop filters are sometimes proposed, either in the phase or in the neutral. A series filter is

intended to block harmonic currents rather than provide a controlled path for them. This creates a large

harmonic voltage drop that appears across the supply on the load side. Since the supply voltage is heavily

distorted, it is no longer within the standards for which equipment was designed and warranted. Some

equipment is relatively insensitive to this distortion, but others are very sensitive. Series filters can be useful in

certain circumstances, but should be carefully applied. They cannot be recommended as a general-purpose

solution.





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ACTIVE HARMONIC CONDITIONERS

The concept of the Active Harmonic Conditioners (AHC) is simple. Power electronics are used to generate the

harmonic currents required by the non-linear loads so that the normal supply is required to provide only the

fundamental current. The load current is measured by a current transformer, the output of which is analyzed

by a DSP to determine the harmonic profile. The current generator uses this information to produce the exact

harmonic current required by the load.

Because the AHC relies on the measurement from the current transformer, it adapts rapidly to changes in the

load harmonics. Since the analysis and generation processes are controlled by software, it is a simple matter to

program the device to provide maximum benefit.

A number of different topologies are available. There are issues for each of them regarding required

component ratings.

OVERSIZING TRANSFORMERS, MOTORS AND CABLES

Harmonics affect transformers in two ways.

Firstly, the eddy current losses—normally approximate 10% of the loss at full load—increase by the square of

the harmonic number. In practice, for a fully loaded transformer supplying a load comprising IT equipment, the

total transformer losses would be twice as high as for an equivalent linear load. This results in a much higher

operating temperature and a shorter life. Fortunately, few transformers are fully loaded, but the effect must

be taken into account when selecting plant systems.

The second effect of harmonics upon transformers concerns the triple-N harmonics. In delta wound

transformers, triple-N harmonic currents continue to circulate in the winding and do not propagate onto the

supply. This means delta wound transformers are useful as isolating transformers blocking triple-N harmonics

from the supply. However, the circulating current has to be taken into account when rating the transformer.

Note that the same effect can be obtained by using a zigzag wound transformer. Note also that all non-triple-N

harmonics pass through.

Concerning motors, harmonic voltage distortion causes increased eddy current losses, in the same way as in

transformers. Additional losses arise due to the generation of harmonic fields in the stator and the induction of

high frequency currents in the rotor. Where harmonic voltage distortion is present, motors should be de-rated

to take into account all of these additional losses.

Where harmonic currents are present, designers de-rate cables to take the skin effect into account. Alternating

current tends to flow on the outer surface of a conductor (skin effect), a phenomenon which is more

pronounced at high frequencies. Skin effect is normally ignored because it has very little effect at power supply

frequencies. However, above approximately 350 Hz, i.e. the seventh harmonic and above, skin effect will

become significant, causing an additional loss that must be taken into account when rating the conductor.

Multiple cable cores or laminated busbars can be used to overcome this problem. Note also that the mounting

systems of busbars must be designed to avoid mechanical resonance at harmonic frequencies.

It is good practice to oversize transformers of Group 2 (and even Group 1) circuits by approximately 20 to 30%

to enhance their reliability.

SHIELDING

Shielding is the use of a conducting and/or a ferromagnetic barrier between a potentially disturbing noise

source and sensitive circuitry. Shields are used to protect cables (data and power) and electronic circuits. They

may be in the form of metal barriers, enclosures, or wrappings around source circuits and receiving circuits.





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STATIC TRANSFER SWITCHES

Fast static switches can be used to connect and disconnect uninterruptable power supply (UPS) systems. They

ensure the uninterrupted operation of the loads, even those that are very sensitive to short supply voltage

decays. Fast static switches can have a switching time below 6 ms to connect the UPS, whereas standard

contactors need tens or even hundreds of milliseconds to switch circuits.

Unlike standard contactors, static switches do not generate switching overvoltages, which is another

advantage. Their application is recommended in environments sensitive to overvoltages, such as circuits with

inductive loads.

STATIC VAR COMPENSATOR

Special fast-acting power electronic circuits, such as Static Var Compensators can be configured to limit the

unbalance. These behave as if they were rapidly changing complementary impedances, compensating for

changes in impedance of the loads in each phase. They are also capable of compensating for unwanted

reactive power. However, these are expensive devices, and are only used for large loads (e.g. arc furnaces)

when other solutions are inadequate.

The impact of cyclic loads, such as spot welders, can be mitigated by the use of a static VAR compensator that

corrects power factor ‘on the fly’ and reduce the impact on the system.

VOLTAGE STABILIZERS

Most voltage dips on the supply system have a significant retained voltage, meaning that energy is still

available, but at too low of a voltage to be useful to the load. Consequently, no energy storage mechanism is

required. Voltage stabilizers rely on generating full voltage from the energy still available at reduced voltage

(and increased current) during the dip. These devices are generally categorized as automatic voltage

stabilizers.

The main types of automatic voltage stabilizers are:

Electro-mechanical

Ferro-resonant or constant voltage transformer (CVT)

Electronic step regulators

Saturatable reactors (Transductor)

Electronic voltage stabilizer (EVS)





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ENERGY EFFICIENCY

Once the safety, reliability, and PQ of the electrical system are guaranteed, attention can go to energy

efficiency. Reduced energy consumption can be a crucial element in mitigating the continuous rise of

hospitalization costs.

When employed as part of a facility-wide energy management program, an energy efficient strategy can help

hospitals proactively manage energy use. Information generated through the program can help hospitals to

redirect energy savings to patient care. This information also provides predictive maintenance indicators,

helping the hospital to reduce equipment downtime.

ELECTRICAL NETWORK

Most energy efficiency gains in electrical installations are based on a single physical principle: the energy losses

in a conductor are inversely proportional to its cross section. This rule counts for cables as well as for the

windings of electric motors and transformers.

The minimum cross-sections of electricity cables is prescribed by the international safety Standard IEC 60364.

However, those standards only take safety aspects into account and not the energy efficiency. Over-sizing the

cross-section compared to this standard is in most cases worth the investment. The cross-section with the

lowest Total Cost of Ownership (TCO) can be calculated out of the load pattern, future electricity prices, and a

discount rate. The resulting energy savings will also positively influence the ecological footprint of the

installation.

Transformers are another part of the electrical system where significant savings can be achieved.

Transformers may seem to have a relatively high energy efficiency compared to other electrical equipment

(typically 98% to more than 99%), but they work in continuous operation and have a long life span (typically 20

to 30 years). As a result, a small efficiency increase can add up to significant savings over the lifetime of a

transformer. In the large majority of cases, high efficient transformers have an attractive life cycle cost.

Payback periods are often less than two years. In addition to the financial premiums, the energy savings also

entail significant environmental benefits.

LIGHTING

The lighting demands of hospitals are complex due to their around-the-clock nature and the effects of lighting

on patients and staff. Lighting accounts on average for 10-15% of the total energy consumption and 40-50% of

the electricity consumption of hospitals and offers abundant opportunities for energy savings.

Commercially available, cost-effective lighting technologies offer the best opportunities to achieve high energy

savings and reduce hospital operations and maintenance costs. Hospitals can benefit, for example from:

Eliminating incandescent lamps and installing high efficient fluorescent or LED lamps

Adopting lighting controls

For example, with reference to exit signs maintaining the same performance (in terms of lux), LED lamps use

less than a third (44 kWh) of the energy consumed by fluorescent (140 kWh) and seven times less than

incandescent (350 kWh). Usually, payback time of interventions such as lamp substitution are very short (one

or only a few years) in case of hospital facilities.

Both low-tech and high-tech solutions for controlling lighting are effective. Many hospitals have adopted a

lighting awareness campaign to train staff to turn off lights when rooms are not in use. Beyond that, high-

performance lighting systems significantly reduce energy usage by ensuring electric lighting is used only when

necessary, in the amount necessary. The following options can save energy without affecting patient care or

facility functionality:





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Incorporating daylight controls in patient rooms and public spaces with large window areas

Integrating controls that enable continuous dimming (100 to 5 % of lamp power)

Installing occupancy sensors in spaces that are frequently unoccupied, such as restrooms, stairwells,

service areas, and mechanical plants

Using sensors that include dimming and stepping options for spaces that utilize daylight

Incorporating exterior motion sensors that save energy and can enhance security

Other lighting related practices and technologies improving the energy performance of new and retrofitted

hospitals are:

Adopting of multiple levels of light—both general ambient and task lighting—in patient and exam

rooms. In patient rooms, bright lights can be turned on during examinations but remain off the rest of

the time. Downtime lighting permits patients to rest while lowering energy usage.

Consolidating lamp inventories by eliminating unnecessary bulb types (different bulbs with the same

purpose).

Maximizing matte or diffuse light-colored surfaces to encourage effective glare-free daylight.

Adopting a lighting strategy for a facility, to be applied in all future designs. Such a strategy should

standardize technologies, utilize control measures consistently (e.g., dimming, occupancy sensors,

daylight), and ensure a consistent look and feel throughout the hospital.





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TECHNICAL CONDITION MONITORING AND ENERGY MANAGEMENT

Electrical systems in medical locations should be subject of on line condition monitoring. Such monitoring may

provide information in advance of dangerous operating conditions (e.g. currents or temperatures),

degradation of conductor insulation, and conductor or connection integrity (continuity).

It may be worthwhile to use the same monitors for energy management purposes. An energy management

system involves implementing a systematic approach to energy efficiency and is superior to ad hoc or

traditional project-based approaches to improving energy performance. Typically, energy management

systems combine best practices in project management, energy monitoring, and energy awareness along with

an energy policy that governs an organization’s approach to energy use. This benefits an organization by

enabling significant energy savings that are persistent. The ISO 50001 standard provides rules for energy

management. For a more detailed introduction to the concept of energy management, see the Leonardo

Energy Application Note Asset and Energy Management [9].

http://www.leonardo-energy.org/good-practice-guide/asset-and-energy-management








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OTHER IMPORTANT ISSUES CONCERNING THE MEDICAL ELECTRICAL SYSTEM

Some other important issues concerning the well-functioning of the medical electricity system are not

included in the IEC standards:

The patient’s quality of life. The IEC standard is adequate for ensuring electrical safety and the

reliability of life-support functions. However, patients want more than just that. The quality of life of

patients inside the hospital can be enhanced by, among other things:

o Minimizing unnecessary repetition of exams. This requires power availability rules that are

much more stringent than those of the IEC standard.

o Providing clear information, and instructions on what to do, in the event of a power

interruption.

Proper training of nurses and doctors. A lack of the personnel’s knowledge of electricity might lead to

improper use of electro-surgery equipment, affecting electrical safety and availability. An adequate

and regular training program on this topic could prevent such problems.





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HVAC

Despite being a thermodynamic system, the Heating, Ventilation, and Air Conditioning (HVAC) of a hospital has

a strong interaction with the electrical system.

INDOOR AIR Q UALITY (IAQ)

The HVAC system for a hospital has to fulfill all of the classical comfort needs of a public building.

Nevertheless, it also has requirements that go beyond that. As patient’s tend to stay in their room 24 hours a

day, maintaining the right temperature, humidity and ventilation level is essential for supporting their

recovery. Another crucial task is to maintain the Indoor Air Quality (IAQ) in all patient environments in order to

limit the bacterial concentration and to avoid any cross-contamination between the patients. More particularly

for operating rooms, the IAQ is subject to stringent requirements. To maintain the correct IAQ, not only

temperature, humidity, and ventilation of each room are regulated, but also the pressure level relative to the

surrounding spaces. All these requirements combine to result in a complex HVAC system that will use at least

50% of all energy consumption of the hospital.

RELIABILITY VERSUS ENERGY EFFICIENCY

Since HVAC is not only crucial for the patients’ comfort, but also for their health, the reliability of the system is

of utmost importance. This means that sufficient redundancy has to be built into the system. Standby

equipment has to be installed to take over in case the first line equipment is out of service. As a result of this

redundancy, the capital investment cost of a hospital’s HVAC system can mount up quickly. This makes it hard

to invest even more in the equipment in order to improve its energy efficiency. Nonetheless, such an

investment can significantly reduce the Total Cost of Ownership of the installation.

The following are four basic concepts to reduce energy consumption of the HVAC system:

ENERGY EFFICIENCY IN STEAM AND HOT WATER PRODUCTION

Boilers represent one of a hospital’s largest facilities -related capital expenditures. They are costly to purchase

and expensive to operate, particularly as the cost of energy continues to rise. Yet boilers, when properly sized,

operated, and maintained, offer major opportunities for hospitals to save energy—resulting in financial and

environmental benefits.

In addition to correct and continuous maintenance and the adoption of co-generation (see further), the main

points of interest for energy efficiency in boilers are:

Correct sizing. Over time, a facility’s energy demand might change. For example, kitchen or laundry

services might be added or outsourced. Hospitals should ensure that replacement boilers are the right

sizes for the actual heating demand. In the USA, it has been determined that effective boiler load

management techniques can save more than 7% of a hospital’s energy use.

Replacing traditional technologies by existing electro-technologies, selecting the most appropriate

technology for the required application

HEAT RECUPERATION

Heat (or cooling) recuperation can be realized by integrating heat exchangers in the ventilation system,

transferring heat from the outgoing air to the incoming air or vice versa.

In the event the hospital has a large cooling need (situated in a hot climate), a heat pump can be connected to

the chiller plant of the air conditioning system. In this way, the heat can be recuperated for producing hot

water.





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CO-GENERATION

Since a hospital has a large and relatively constant need for heating/cooling and hot water, it might be

advantageous to install a co-generation system on site.

The basic principle of co-generation is to simultaneously produce electricity and heat. The overall efficiency of

such a system is higher than if electricity and heat are produced separately.

Various types of co-generation technologies exist. In case of a hospital, co-generation with a gas motor is the

most obvious choice. Such a motor is fuelled by natural gas and drives an electricity generator. Depending

upon the needs, heat can be recuperated in the intercooler (30-80 °C), the lubrication oil (75-95 °C), the

cooling water (75-120 °C), and the exhaust gasses of the motor (400-550 °C).

A co-generation system should be dimensioned according to the heat requirements of the premises. Since the

system will be coupled to the electricity grid, any surplus in electricity can be supplied to the grid, and any

shortage can be taken from the grid. However, any heat surplus will inevitable be lost. Such heat losses

seriously compromise the efficiency of the system. To avoid this, the co-generation system is best conceived as

an installation for heat production, while electricity is seen as a bonus that helps to pay-off the investment.

That said, the electricity from the co-generation unit that is consumed locally will be less expensive than grid

electricity, as it avoids transmission and distribution charges. In many countries, the electricity and heat

produced through co-generation is rewarded with certificates, compensating for the carbon emission

reductions.

In some cases, the co-generation unit can be used as an emergency generator. This should not prevent the co-

generation unit from being dimensioned based on heat demand. Designed in this way, the unit can only be

used as an emergency generator if its electrical output at least equals the required emergency power.

MOTOR SYSTEM EFFICIENCY

HVAC systems include many electrical motors, mainly pump and fan motors. Important efficiency gains in

those motor systems can be achieved.

A first step is the proper sizing of the motor, as the energy efficiency of motors drops significantly when

operating above or under their nominal load. This means that the HVAC system should be designed to be as

efficient as possible in order to minimize the required motor power. Later efficiency gains at the mechanical

side will have a reduced impact if they result in a motor operating under its rated power.

For systems requiring a variable output, the type of motor control that is used is crucial for its efficiency. Best

practice is to avoid mechanical control systems (throttles, gearboxes, etc.) and change the output by means of

a variable speed drive (VSD) connected to the motor. A throttle has a typical efficiency of 66%, while the

efficiency of a VSD can easily mount up to 96%.

A large difference in energy efficiency can also be made in the electrical motor itself. While a standard

induction motor typically has an efficiency of 90%, a High Efficient Motor (HEM) can have an efficiency of 95%

and more. In the EU, the efficiency of induction motors is labeled Eff 3, Eff 2 and Eff 1, the latter being the

highest efficiency category. With the exception of motors with a very low intensity of use, Eff 1 motors will

always have the lowest Total Cost of Ownership. In 2008, a new international standard for the efficiency of

electric motors was introduced (IEC 60034—30). Contrary to the EU label, the numbers corresponding with

this new standard go up with increasing efficiency (IE 1, IE 2, IE 3, and IE 4). The lowest efficiency category of

this new international label (IE 1) corresponds approximately with the middle category of the EU labels (Eff 2).

The following example shows how the efficiency of a pump system can be increased from 31% to 72% by

selecting the right equipment:





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Conventional pumping system High efficient pumping system

Device Efficiency Device Efficiency

Standard Induction Motor 90% High efficient induction motor 96%

Variable speed drive (VSD) 95%

Coupling 98% Efficient coupling 99%Pump 77% Efficient pump 88%

Throttle 66%

Pipe 69% Energy efficient pipe 90%

Total pumping system 31% Total pumping system 72%

(Source: Efficiency in Motor Driven Systems, Ronnie Belmans, Wim Deprez, KULeuven)

Motors are often integrated into bigger entities purchased entirely from an OEM. This barrier can be

countered by writing the use of Eff 1 (IE 3 or IE 4) motors and VSDs into the general equipment specifications

of the hospital.

Note that operation and maintenance conditions can also affect the efficiency of a motor system. An

important factor to verify is the quality of the power supply. Voltage unbalance and harmonics are just two

examples of power quality issues that can seriously deteriorate motor efficiency.





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COMPRESSED AIR

MEDICAL AND TECHNICAL COMPRESSED AIR

The international standards for compressed air in hospitals distinguishes between medical and technical

compressed air.

Compressed air that drives surgical tools is considered medical compressed air and has to follow the standards

of medical gasses. More specifically, Standard ISO 7396-1:2007 specifies requirements for design, installation,

function, performance, documentation, testing, and commissioning of the distribution systems of medical

gasses.

Central medical gas systems are Class IIb medicinal products. This means equipment manufacturing for those

systems should comply with ISO EN 7396 – 1.

Both medical and technical compressed air has to comply with ISO 8573-1:2010, which specifies the purity

classes of compressed air with respect to particles, water, and oil. ISO 8573-1:2010 also specifies gaseous andmicrobiological contaminants.

ENERGY EFFICIENCY OF COMPRESSED AIR

Compressors—no matter whether they supply a medical or a technical compressed air system —are driven by

an electric motor. Consequently, what applies for fans and pumps, also applies for compressors: by opting for

high efficient motors (HEMs) and variable speed drives (VSDs), important energy efficiency gains can be

achieved that significantly reduce the Total Cost of Ownership of the installation (see also: HVAC, motor

system efficiency)

Other important energy savings in compressed air systems can be made by:

Limiting demand: avoiding inappropriate use of compressed air, and limiting pressure drops to real

needs.

Reducing distribution losses through good design of the piping network, regular maintenance, and the

repairing of leaks.

Reducing the air inlet temperature: approximately 0.3% of the energy is saved with each degree. By

placing the inlet outside, at the north end of the building, and far away from heat sources,

temperature can often be reduced by 10 °C, resulting in energy savings of 3.5%.

Heat recovery: installing a heat recovery system can have pay-back periods of less than two years.

Central control: in larger, more complex compressed air systems, a centralized control system will

ensure energy efficient responses. Building Automation and Auxiliary Systems





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AUXILIARY SYSTEMS

Many auxiliary systems in hospital buildings are driven by electric motors. Examples include elevators,

automatic sliding doors, and automatic sunshades. For those motors, just as for the ones in HVAC and

compressed air systems, opting for a High Efficient Motor (HEM) controlled through a Variable Speed Drive

(VSD) can significantly reduce their energy consumption and the Total Cost of Ownership of the system.

CONVENTIONAL BUILDING AUTOMATION SYSTEMS

In many tertiary sector buildings, building automation systems are used to improve control of lighting and

HVAC systems and limit their energy consumption. Those systems can, among other things, switch off the

lights when enough natural light is entering the room, switch off the air-conditioning when windows are

opened, set the heating at lower during night-time, automatically control sunshades, et cetera. In buildings

that operate 24 hours a day, 7 days a week, as a hospital does, the efficiency gain achieved by those systems is

limited—although it is still worthwhile investigating their potential benefit. Moreover, hospitals also include

rooms that are only operational during working hours—think of offices for instance. In many cases, building

automation systems can increase the feeling of comfort of patients and personnel.

According to European Standard EN 15232, buildings with a class A building automation system achieve

significant energy savings compared to buildings with no building automation system at all. The savings in

electrical energy are estimated to be 9%. The savings in thermal energy are estimated to be 34%.

PATIENT ASSISTANCE AND TELEMEDICINE

Assistance to patients is preferable automated as much as possible. Patients will feel more self-supporting and

less embarrassed if they are assisted by an electrically driven system than if they have to call on the personnel

for all help. In this way, the contact with the personnel will be more dedicated to what automates cannot

provide, i.e. human conversation.

Automated diagnoses and check-ups can increase the patient’s feeling of control. This increased involvement

will often boost the patient’s spirit and in this way speed up recovery.

Some of those systems can also be used outside the hospital. By returning hom e faster, the patient’s quality of

life will improve while treatment costs are reduced by saving on manpower. A positive example of this concept

is the Carme Project in Catalunya, Spain, providing telemedicine for cardiac patients. Thanks to this project,

the perception of the patient’s quality of life increased by 72%, while the days in hospital of cardiac patients

decreased by an equally impressive 73%.

To fully harvest the advantages of telemedicine, three important aspects require attention. Firstly, the

hospitals ICT system should be properly adjusted for integrating the telemedicine system and for reliablyprocessing all signals. Secondly, doctors and patients should have full confidence in the system, otherwise it

will only function as an addition on top of to the current techniques and costs will rise instead of going down.

This confidence can only be expected when choosing mature systems with proven performance, and when

appropriate training is provided for doctors and all personnel involved.

HOSPITAL COMMUNICATION SYSTEMS

Concerning the communication systems in hospitals, reliability is the main point of attention. Achieving a high

reliability for communications systems is only possible when the power supply to those systems is equally

reliable. For the reliability of the power system, see chapter I.1.2 Ensuring reliability.





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CONCLUSIONS

A hospital’s first concern regarding the electrical installation is to ensure safety and the reliability of life-

support equipment.

The international Standard IEC 60364-7-710 for medical locations in buildings is very comprehensive regardingelectrical safety. It classifies medical rooms into three groups and prescribes regulations for each of these

groups.

The same standard also includes some essential rules for ensuring a reliable power supply to vital equipment

and emergency lighting. However, several additional elements regarding reliability have to be considered. To

avoid electric or electronic devices from disturbing each other with electro-magnetic signals, a proper

functional earthing is required. This is regulated by the Standard IEC 60364-7-707. It requires, however, a

specialized engineer to implement it.

A specialized engineer is also required for ensuring a proper power quality in the hospital’s electric net work.

This is not limited to the reliability of the public grid; it is often the medical device itself that injects electric

pollution into the local network. Ensuring power quality at the point of connection with the grid alone is

consequently not sufficient.

The ambition of a hospital concerning the reliability of power supply should also go beyond the supply of life-

supporting equipment. The patient’s quality of life can be improved significantly by minimizing the downtime

of any type of electrical device.

Energy efficiency is often treated as a stepchild in hospitals, as it is less vital than immediate safety and

reliability. This is unfortunate, because energy efficiency improvements can result in significant reductions of

the total cost of ownership of the installations. Those cost reductions can be of benefit for the hospital, the

patients, and public healthcare in general. One way to minimize energy losses is to choose a larger cross-

section for electric conductors than is required by safety prescriptions. High efficiency transformers can also

make a significant difference. Perhaps the biggest efficiency gain that can be made is by adopting High Efficient

Motor systems. Electric motors are integrated at various places in hospitals: in the fans and pumps of the

HVAC system, in the compressors for medical and technical compressed air, and in auxiliary systems like

elevators and sliding doors. Since those systems are generally purchased through OEMs, energy efficiency

should be tackled in the general specifications given to the OEM.

For providing the hospital’s heating and hot water needs, a co -generation system with natural gas motor will

be advantageous in many cases. Such a system simultaneously generates heat and electricity, with a higher

efficiency than is the case with separate generation.

Another potential measure for reducing the hospital’s energy consumption is the implementation of building

automation systems. When properly adopted, those systems can reduce the thermal energy need by up to

34%.



REFERENCES

[1] IEC 60364-7-710 Electrical installations of buildings—Part 7-710: Requirements for special

installations or locations—Medical locations

[2] IEC 60364-7-707 Electrical installations of buildings—Part 7: Requirements for special installations orlocations. Section 707: Earthing requirements for the installation of data processing equipment

[3] IEC 61557-8 Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c.—

Equipment for testing, measuring or monitoring of protective measures—Part 8: Insulation monitoring devices

for IT systems

[4] IEC 62-305 Protection against lightning

[5] IEC 60034—30 Rotating electrical machines—Efficiency classes of single-speed, three phase, cage-

induction motors

[6] ISO EN 7396—1 Medical gas pipeline systems—Part 1: Pipelines for compressed medical gases andvacuum

[7] ISO 8573-1 Compressed air—Part 1: Contaminants and purity classes

[8] A.Baggini, Handbook of Power Quality, Wiley 2008 Chichester

[9] Martin Van den Hout, Asset and Energy Management, Leonardo Energy Application Note 2014

Cu0114 WP Electricity for Hospitals v2

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Transcript of Cu0114 WP Electricity for Hospitals v2