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Electricity is only of third-rate interest to hospitals. Their core business is the welfare of its patients, for which medical appliances are required, which, on their turn, require electricity. That ...

Electricity is only of third-rate interest to hospitals. Their core business is the welfare of its patients, for which medical appliances are required, which, on their turn, require electricity. That said, electricity is a vital utility and any malfunction or interruption can easily lead to disastrous consequences. This combination - being absolutely vital but far from the main interest domain of the organization – entails a certain risk.

Standards and regulations prescribe how a hospitals’ electrical installations should be conceived to ensure safety and reliability. Those regulations are complemented by the prescriptions of the equipment manufacturers. All these rules, however, create a complex tangle for the user, making it difficult to figure out which rule has to be applied where and how exactly 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 on energy efficiency, hospitals can often make surprisingly large savings on the total cost of ownership (TCO) of their installations. In this paper, we will tackle a few major energy efficiency topics relevant to medical building management.

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Cu0114 wp electricity for hospitals_v2 Document Transcript

  • 1. European Copper Institute WHITE PAPER ELECTRICITY SYSTEMS FOR HOSPITALS Angelo Baggini November 2011 ECI Publication No Cu0114 Available from www.leonardo-energy.org/drupal/node/6121
  • 2. Publication No Cu0114 Issue Date: November 2011 Page i Document Issue Control Sheet Document Title: White Paper – Electricity for Hospitals Publication No: Cu0114 Issue: 02 Release: November 2011 Author(s): Angelo Baggini Reviewer(s): Bruno De Wachter Document History Issue Date Purpose 1 March 2011 Initial release 2 November 2011 Adapted for adoption into the Good Practice Guide 3 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.
  • 3. Publication No Cu0114 Issue Date: November 2011 Page ii CONTENTS Summary ........................................................................................................................................................ 1 The General Electrical Installation .................................................................................................................. 2 Safety and Reliability ..............................................................................................................................................2 Ensuring safety: standard IEC 60364-7-710 .............................................................................................2 Ensuring reliability....................................................................................................................................5 Functional earthing ..................................................................................................................................7 Equipment specifications .........................................................................................................................7 Protection against lightning .....................................................................................................................7 Power Quality .........................................................................................................................................................8 Causes of power quality problems...........................................................................................................8 Solutions.................................................................................................................................................10 Energy Efficiency...................................................................................................................................................13 Electrical network...................................................................................................................................13 Lighting...................................................................................................................................................13 Other Important Issues Concerning the Electrical System ...................................................................................15 HVAC ........................................................................................................................................................ 16 Indoor Air Quality (IAQ)........................................................................................................................................16 Reliability versus Energy Efficiency.......................................................................................................................16 Energy efficiency in Steam and hot water production...........................................................................16 Heat recuperation ..................................................................................................................................16 Co-generation.........................................................................................................................................17 Motor system efficiency.........................................................................................................................17 Compressed air............................................................................................................................................. 19 Medical and Technical Compressed Air................................................................................................................19 Energy Efficiency of Compressed Air....................................................................................................................19 Building Automation and Auxiliary Systems ................................................................................................. 20 Auxiliary Systems..................................................................................................................................................20 Conventional Building Automation Systems ........................................................................................................20 Patient Assistance and Telemedicine ...................................................................................................................20
  • 4. Publication No Cu0114 Issue Date: November 2011 Page iii Hospital Communication Systems ........................................................................................................................20 Conclusions................................................................................................................................................... 22 References.................................................................................................................................................... 23
  • 5. Publication No Cu0114 Issue Date: November 2011 Page 1 SUMMARY Electricity is only of third-rate interest to hospitals. Their core business is the welfare of its patients, for which medical appliances are required, which, on their turn, require electricity. That said, electricity is a vital utility and any malfunction or interruption can easily lead to disastrous consequences. This combination - being absolutely vital but far from the main interest domain of the organization – entails a certain risk. Standards and regulations prescribe how a hospitals’ electrical installations should be conceived to ensure safety and reliability. Those regulations are complemented by the prescriptions of the equipment manufacturers. All these rules, however, create a complex tangle for the user, making it difficult to figure out which rule has to be applied where and how exactly 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 on energy efficiency, hospitals can often make surprisingly large savings on the total cost of ownership (TCO) of their installations. In this paper, we will tackle a few major energy efficiency topics relevant to medical building management.
  • 6. Publication No Cu0114 Issue Date: November 2011 Page 2 THE GENERAL ELECTRICAL INSTALLATION SAFETY AND RELIABILITY ENSURING SAFETY: STANDARD IEC 60364-7-710 All low voltage electrical installations have to comply with the general international standard for electrical safety IEC 60364. Section 710 of this standard is dedicated in particular to medical locations, prescribing some additional requirements for these premises. 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 locations are derived from IEC 60364-7- 710. It applies to hospitals, medical clinics, medical and dental surgeries, rooms for physiotherapy, beauty centres, and veterinary surgeries. The standard also applies to medical rooms integrated into non-medical buildings, such as industrial premises, offices, or residential buildings. Although it is primarily a safety standard, it also provides some rules on ensuring availability (see further). Standard IEC 60364-7-710 classifies all medical rooms into three groups, primarily based on the use of ‘applied parts’. An ‘applied part’ is any part of an electro-medical device that might come into contact with a patient.  Group 2 includes all rooms where a discontinuity 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 with general anaesthesia: pre-operation rooms, operating theatres, surgical plaster rooms, and post-operative recovery rooms.  Group 1 includes all medical locations that do not belong to Group 2 and where applied parts are used, externally or invasively.  Group 0 includes all medical locations where no applied parts are used, such as outpatient rooms, massage rooms without electro-medical devices, offices, store rooms, canteens, changing rooms, corridors, staff hygiene facilities, waiting rooms, etcetera. Qualified medical personnel must carry out the assigning of the rooms to one of these three groups. If no such personnel are available, the national healthcare organization must be called in. Often, the function of a room is 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. The IEC standard prescribes the following protective measures for each group: For Group 0, no extra measures have to be taken, additional to the general prescriptions for electrical safety in buildings (Standard IEC 60364). For Groups 1 and 2, additional measures are prescribed for protection against electrocution through direct or indirect contact with live parts of the system. ‘Direct contact’ means a person touches a live part of the electrical system. Indirect contact means a person touches a conductive (metal) part which is normally not live, but which has become live due to a fault in the electrical insulation.
  • 7. Publication No Cu0114 Issue Date: November 2011 Page 3 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. For protection against indirect contact, the following measures are prescribed. PROTECTION THROUGH AUTOMATIC CIRCUIT BREAKING The Standard IEC 60364-7-710 specifies that the protection must be compatible with the earth connection method used by the network. In case a TN earthing connection method is used, an automatic miniature circuit breaker is sufficient, but a Residual Current Device (RCD) is advisable. The reaction times of the protection 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 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 that, 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.
  • 8. Publication No Cu0114 Issue Date: November 2011 Page 4 Note that in any case for medical locations:  The protection device should bring the possible contact voltage in case 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 THROUGH MEDICAL IT SYSTEM 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 those powering devices of more than 5 kVA and radiological devices) 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 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 Standard IEC 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 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 case 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. PROTECTION THROUGH CLASS II DEVICES
  • 9. Publication No Cu0114 Issue Date: November 2011 Page 5 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 VOLTAGE (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. 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 windows, 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 locations of Group 1 and Group 2. 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 A first category of measures to provide a high reliability of power supply are 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
  • 10. Publication No Cu0114 Issue Date: November 2011 Page 6 by subdividing the system into many different circuits with each 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 case of blackouts or power interruptions. Although mainly 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)  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 cabinets, electrical switchboards, or generation sets  Rooms providing essential services, such as elevator motors, kitchens, air conditioning stations, data processing centres et cetera In case 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 static Uninterruptable 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.
  • 11. Publication No Cu0114 Issue Date: November 2011 Page 7 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 IEC 60364-7-710, but in another section of the same general standard (i.e. IEC 60364-7-707). To ensure EMC, a 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 number IEC 60601-xx. In addition to these, 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.
  • 12. Publication No Cu0114 Issue Date: November 2011 Page 8 POWER QUALITY 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 on 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 good 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 behaviour 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.
  • 13. Publication No Cu0114 Issue Date: November 2011 Page 9 Figure 2: Oscilloscope screenshot of the mains electrical behaviour during angiography showing sinusoidal voltage and distorted currents. 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 mainly 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 the electricity 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
  • 14. Publication No Cu0114 Issue Date: November 2011 Page 10 and may even indirectly cause overvoltages on the other phases. The system behaviour 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. 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 part 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
  • 15. Publication No Cu0114 Issue Date: November 2011 Page 11 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. 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 programme 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 Transformers are affected in two ways by harmonics. 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 on 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.
  • 16. Publication No Cu0114 Issue Date: November 2011 Page 12 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. 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. 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)
  • 17. Publication No Cu0114 Issue Date: November 2011 Page 13 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 round-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
  • 18. Publication No Cu0114 Issue Date: November 2011 Page 14 necessary, in the amount necessary. The following options can save energy without affecting patient care or facility functionality: • 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-coloured 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.
  • 19. Publication No Cu0114 Issue Date: November 2011 Page 15 OTHER IMPORTANT ISSUES CONCERNING THE ELECTRICAL SYSTEM Some other important issues concerning the well-functioning of the 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 case 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 programme on this topic could prevent such problems.
  • 20. Publication No Cu0114 Issue Date: November 2011 Page 16 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 QUALITY (IAQ) The HVAC system for a hospital has to fulfil 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 result in a complex HVAC system that will use at least 50% of all energy consumption of the hospital. RELIABILITY VERSUS ENERGY EFFICIENCY As 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 point 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.
  • 21. Publication No Cu0114 Issue Date: November 2011 Page 17 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 on 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 labelled 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, 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:
  • 22. Publication No Cu0114 Issue Date: November 2011 Page 18 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.
  • 23. Publication No Cu0114 Issue Date: November 2011 Page 19 COMPRESSED AIR MEDICAL AND TECHNICAL COMPRESSED AIR The international standards on 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 and microbiological 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.
  • 24. Publication No Cu0114 Issue Date: November 2011 Page 20 BUILDING AUTOMATION AND AUXILIARY SYSTEMS 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 buildings of the tertiary sector, 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 esprit de corps and in this way speed up recovery. Some of those systems can also be used outside the hospital. By returning home 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 reliably processing 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
  • 25. Publication No Cu0114 Issue Date: November 2011 Page 21 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.
  • 26. Publication No Cu0114 Issue Date: November 2011 Page 22 CONCLUSIONS A hospital’s first concern regarding the electrical installation is to ensure safety and the reliability of life- supporting equipment. The international Standard IEC 60364-7-710 on medical locations in buildings is very comprehensive regarding electrical 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 network. This depends not only on the reliability of the public grid; often it are the medical devices that inject ‘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 safety and reliability. This is a pity, 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. 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 in case of 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%.
  • 27. Publication No Cu0114 Issue Date: November 2011 Page 23 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 or locations. 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 and vacuum [7] ISO 8573-1 Compressed air -- Part 1: Contaminants and purity classes [8] A.Baggini, Handbook of Power Quality, Wiley 2008 Chichester