How To Understand Power Factor Correction

Transcription

1 Australian Building Codes BoardPower Factor Correction Evaluation Peter KoulosDean Eislers12 July Sept 2002C19 July 2002ReportClient SubmissionAustralian Building Codes Board ` NORMAN DISNEY & YOUNG Level 10 1 Chandos Street ST LEONARDS AUSTRALIA sydney@ndy.com MANAGEMENT PTY LIMITED ACN ABN QUALITY ENDORSED COMPANY ISO 9001 LIC 1608/01 STANDARDS AUSTRALIA` REPORT Revision: C Power Factor Correction Evaluation Issued: 04 Sept 2002 NORMAN DISNEY & YOUNG 1 Chandos Street, ST LEONARDS Telephone : Facsimile : sydney@ndy.com WEB : Australian Building Codes Board COPYRIGHT Copyright 2002 by Norman Disney & Young All rights reserved. No part of the contents of this document may be reproduced or transmitted in any form, or by any means, by parties other than those employed or engaged by the Australian Building Codes Board, and only in direct connection with the purpose for which this document has been provided by Norman Disney & Young, without the written permission of Norman Disney & Young.

2 Issued : 19 July 2002 Table of Contents 1 2 Executive Summary...1 Introduction Objectives of Study Authority Information Sources Outline Definitions and Terms Revision History Power Factor Correction Introduction...4 Figure 1 Power triangle showing relationship between real power, reactive power, apparent power and power factor...4 Figure 2 Model of a typical load...4 Figure 3 - Effect of power factor correction on line current...5 Figure 4 Line currents at various points in power network Resonance Ripple Control Heat Load Applications Energy retailer tariff structures & requirements Electricity Prices...9 Table 1 - Central Business Districts and their associated franchises (as at July 2002)...9 Table 2 - Regional centres and their associated franchises (as at July 2002)...10 Figure 5 - Average electricity retail prices by State 2001/ Figure 6 Domestic Electricity Prices 2001/ Figure 7 Business electricity prices 2000/ Figure 7 Business electricity prices 2000/ Minimum Power Factor Specifications...13 Table 3 National Electricity Code Permissible Power Factor Ranges (Table S5.3.1)...13 Table 4 Distribution Network Service Providers and their Power Factor Requirements...14 Table 5 Victorian Power Factor Requirements (all Network Service Providers)...15 Table 6 South Australian Power Factor Requirements (ETSA) Expected and Recommended Power Factors and Maximum Loads Recommended Power Factor Where to install PFC equipment Typical Efficiencies of Electric Motors in the Building Industry Typical efficiencies...23 i

3 Issued : 19 July 2002 Table of Contents Table 7 MEPS Minimum Efficiency Levels for Three Phase Electric Motors - Test Method A.25 Table 8 MEPS Minimum Efficiency Levels for Three Phase Electric Motors - Test Method B..26 Table 9 MEPS Minimum High Efficiency Levels for Three Phase Electric Motors - Test Method A...27 Table 10 MEPS Minimum High Efficiency Levels for Three Phase Electric Motors - Test Method B Power factor and motor efficiency Methods of Power Factor Correction Static Correction Switched Capacitor Banks Synchronous Condensers Electronic Lighting Ballasts Correctly Sized Motors Indicative Power Factor Correction Installation Costs and Space Requirements Table 11 Indicative Installation Costs for 525 Volt Capacitors Cost savings using Power Factor Correction...32 Table 12 Power Factor Correction Installation Payback Calculation Indicative Physical Space Requirements Conclusion...34 Appendix A NEM Retail Market Participants...35 Appendix B - References...37 Appendix C Figure 8 NSW Electricity Supply Boundaries...38 Figure 9 - ACT Electricity Supply Boundaries (single NSP)...39 Figure 10 - Energex Electricity Supply Boundaries...40 Figure 11 - Western Australia Electricity Supply Boundaries...41 Figure 12 Victorian Electricity Supply Boundaries...42 ii

4 1 Executive Summary Electrical energy efficiency is of prime importance to industrial and commercial companies operating in today's competitive markets. Optimum use of plant and equipment is one of the main concerns that industry tries to balance with energy efficiency, for both economical and environmental reasons. As society becomes increasingly conscious of its impact on the environment, reduced energy consumption becomes more desirable, which, is an achievable goal for everyone. Through the use of measures such as power factor correction, electricity consumption is optimised, which ultimately leads to reduced energy consumption and reduced CO 2 greenhouse gas emissions. This report introduces the concept of power factor correction and its use in reducing power consumption. This is followed by indicative electricity costs around Australia along with the minimum power factors required by Network Service Providers (NSP s). The expected typical power factor and maximum demands for various building forms and classes have been presented along with recommended power factors for these buildings. Motors are an integral part of many commercial and industrial buildings, and are commonly used for a number of applications including air conditioning and pumping. Efficiency requirements of electric motors have been listed for different sizes, and the benefits to both industry and society of using higher efficiency motors outlined. Finally a brief summary of power factor correction methods is presented and indicative costs of installation for the most common type of commercial developments. Within a cost conscious market, payback considerations are also important. This report identifies the most appropriate application for power factor correction based on energy consumption, tariff metering, cost payback and emission reduction. Power factor correction is an appropriate means by which to improve the power quality of an installation. Its application is dependent though on the size of the installation and the extent that power factor correction needs to be applied. The opportunity however exists to make a significant environmental contribution whilst simultaneously providing economic benefit. This report identifies such issues and concludes with the recommendation that provisions be made in the Building Code of Australia for power factor correction. 1

5 2 Introduction 2.1 Objectives of Study The objective of this report is to provide an evaluation of the application of power factor correction based on building size, type and use and whether provisions should be made for its inclusion in subsequent revisions of the Building Code of Australia. 2.2 Authority Authority to undertake this report was provided by Dr Ernest Donnelly of the Australian Building Codes Board. Report commission date: 25 June 2002 Draft Report submission date: 19 July 2002 Final Report Submission date: 04 Sept Information Sources References for this report are included in Appendix B. 2.4 Outline This report provides: Recommendations where power factor correction should be applied. Average electricity prices both domestic and commercial for capital cities and the regional centres of Cairns, Coffs Harbour, Mt Isa, Geraldton, Alice Springs, Kalgoorlie, Charleville, Albury and Wagga Wagga. The minimum power factor that supply authorities specify for the aforementioned locations of various building forms designated A to E as noted in this report. The range of power factors and maximum loads (in kva) that could be expected in the various building forms A to E. Typical efficiencies of electric motors used in the building industry and the impact of higher efficiency motors on power factor. Estimates of what minimum power factor should be set and for what building demand. Indicative costs to install power factor correction to achieve the recommended minimum based on the building demand. A recommendation on whether power factor correction should be included in the provisions. 2

6 2.5 Definitions and Terms Power factor (pf) Real Power Apparent Power Reactive Power Lagging PF Leading PF Power Angle Induction motor A figure quantifying the relationship between apparent power and real power. For a linear load it also relates the phase of the current and voltage waveforms through an electrical element; pf = cos(φ) = kw/kva where φ is the angle between the current and voltage waveforms. Rate of energy dissipation in the resistive component of an electrical element. Measured in kw. The vector summation of the real and reactive power representing the total power usage. Also known as Complex Power. Measured in kva. Rate of energy usage in the inductive/capacitive component of an electrical element. Also known as Imaginary Power. Measured in kvar. A system is said to have a lagging power factor when the current waveform lags the voltage waveform. This is experienced with loads with a dominant inductive component. A system has a leading power factor when the current waveform leads the voltage waveform. This is experienced with loads with a dominant capacitive component. The angle φ where cos(φ) = kw/kva = pf, the ratio of real power to apparent power. For linear loads it is also the phase difference between the current and voltage waveforms. The angle needs to be qualified by stating whether it is a leading or lagging PF. A common type of motor used in industry. Its name relates to its construction and mode of operation. Transmission Network The section of the network from where the electricity is produced (i.e. power station) to the distribution network. The voltages are stepped up to minimise transmission losses for subsequent downstream transmission to end-users. Distribution Network The end point of a transmission system where the voltages are stepped back down and distributed at useable voltages to customers. 2.6 Revision History Description Revision Date Issued Comment First Issue A 12 July 2002 Draft Review Second issue B 19 July 2002 Client Review This Issue C 04 Sept 2002 Client Submiss ion 3

7 3 Power Factor Correction 3.1 Introduction The power factor of a system refers to the relationship between real/working power and reactive power. It is a measure of how efficiently electrical power is being used and for linear loads it also relates the phase of the voltage waveform to the current waveform. Electrical power is composed of two orthogonal components real power (component that does the work) and reactive power (component that develops and maintains electromagnetic fields) which when added vectorally make up Apparent power. This is represented on the power triangle below. Figure 1 Power triangle showing relationship between real power, reactive power, apparent power and power factor VAR s Power = cos (φ) = kw = Real Power factor kva Apparent Power Apparent Power (Volt-Amps) Reactive Power (VAR) φ Real Power (Watts) Watts A load typically has a resistive component and a reactive component as depicted in the figure below. Real power, measured in kw is dissipated in the resistive component performing the work of the system and provides the motion or heat. Reactive power is measured in kvar s and doesn t contribute to work as such but rather sustains the electromagnetic field required for the device to operate. It is this level of reactive power compared to real power that determines the power factor. For a heater (which is a pure resistive load) the reactive power is zero; the voltage and current waveforms are in phase, the power angle is zero and hence the power factor, pf = cos(0) = 1. For a motor that requires an electromagnetic field to operate the power factor may be around 0.8. Figure 2 Model of a typical load 4

8 Although the current through the reactive component (I reactive ) dissipates no power (and is hence not measured by a kwh meter), this current still needs to be transmitted along the distribution lines and hence will dissipate energy through other resistive components in the system (cabling, switchgear, distribution boards, etc). By generating/providing this reactive current locally through the use of power factor correction equipment, less power needs to be provided by the distribution network resulting in lower losses, improved line voltage and a lower electricity bill under a kva tariff structure. Reactive power can be supplied via a method of power factor correction involving the installation of capacitor banks. Typically these consist of switched capacitor banks providing bulk correction to a whole building with control equipment switching the level of capacitance to optimise the power factor. Another method is static correction in which the capacitors are attached to individual pieces of equipment and are switched in and out as the device is switched on and off. The capacitors by supplying reactive power have the effect of reducing the magnitude of the line current as shown on the diagram below. Figure 3 - Effect of power factor correction on line current Magnetising Current (Amps) Equipment Load Current Required Equipment Magnetising Current Capacitor supplied Reactive Current θ φ Compensated Line Current Equipment Work Current Work Current (Amps) It is clear from the diagram above the effectiveness of power factor correction in reducing the line current and associated losses. The capacitance supplied by the power factor correction equipment provides reactive power locally reducing the power angle from θ to φ resulting in a reduction in the line current between the power factor equipment and the electricity network. The net effect is a reduced electrical load as seen by the electricity network and for those on kva electricity tariffs electricity bill savings. It should be noted that while the line current between the distribution network and power factor correction equipment is reduced, the current between the power factor correction equipment and the equipment remains unaltered. Hence the power supply and associated cabling to the equipment from the power factor correction equipment needs to be sized for the original equipment requirements. This is illustrated on the following diagram. 5

9 Figure 4 Line currents at various points in power network Power triangle Power triangle 11kV 415V Distribution Network Main Switchboard Load Power Factor Correction 3.2 Resonance An important but often overlooked issue associated with power factor correction is that of resonance. A series or parallel combination of inductance and capacitance has associated with it a natural frequency at which resonance will occur. Some devices such as antennas use this property to its advantage however in a power system resonance can be very damaging. By adding capacitors in an attempt to improve the power factor, resonance with inherently inductive power lines can occur when excited by harmonics generated by electrical equipment such as switch mode power supplies commonly used in personal computers and UPS systems. The impact of resonance on a power factor correction system is that it could significantly reduce the life of the capacitors or destroy them. A solution to this is to include detuned reactors in the design of power factor correction equipment. By introducing a known reactance, the resonant frequency of the system can be chosen to filter out harmonics and improve power quality. Systems are commonly tuned to approximately 190 Hz acting as a low pass filter to limit the 5 th harmonic (250Hz for 50Hz supply) and higher. Low temperature rise reactors in the detuning circuitry are recommended, to reduce heat load. 3.3 Ripple Control Ripple control signals are used by supply authorities as a load control system for the switching of water heaters, street lighting and meter equipment. Where power factor correction capacitors are installed and the electricity distributor uses ripple control, it may be necessary for the customer to install additional equipment to block the electricity distributor s ripple control signals. At audio signal frequencies, capacitors present an impedance of some 10 to 21 times less than at 50Hz. This can result in a significant portion of the signal being absorbed or lost to the system. The effect on the signal voltage of the control system is variable, depending on the size and number of capacitors and their distribution in the high and low voltage network. In the worst case the capacitor impedance may approach or equal the inductive reactance of the distribution transformer(s), to form a series resonance combination and a virtual shortcircuit on the ripple system. This undesirable and unacceptable condition can be avoided by connecting blocking inductors in the capacitor bank. Shunt capacitors used for power factor correction are likely to cause significant loss to the ripple control signal. Their impedance to the frequency must be increased by connecting either 6

10 BLOCKER, REJECTER or STOPPER circuits to a value which will prevent interference to the electricity distributor s ripple control system Heat Load Power factor correction equipment generates heat loads which requires extraction to ensure the operating temperature remains within acceptable limits. Capacitors generate in the order of 0.2W/kVAR heat load. Detuning reactors each generate approximately 100W, one of which is required per 50 kvar bank. The following table outlines the approximate heating loads for some standard size units. Unit Size (kvar) Approximate Heating Load (kwr) When choosing a location for the installation of PFC equipment, consideration to present cooling systems available in the area needs to be made. 1 Section 6 New South Wales Service and Installation Rules March

11 4 Applications The major application of power factor correction is in reducing the maximum demand of apparent power (kva) consumed by the customer as measured by the supply authority. In reducing the maximum demand the customer is able to markedly reduce their electricity bill as a result of the way energy retailers charge their customers. There is also an environmental benefit as a result of more efficient electricity use. Larger customers are billed according to not only the real power they consume but also the level of apparent power the network needs to provide to them. This structure apart from normal kwh metering also includes a maximum demand charge, which is based on kva demand metered on a half hourly basis, which reflects the customers power factor. The customer is charged for the kilowatt-hours used but a surcharge is then applied according to the maximum kva drawn at any one point during the billing period. As such, cost savings may be realized by reducing the maximum kva drawn through the installation of power factor correction equipment. In residential installations, standard residential tariffs only measure the kilowatt-hours used which is unaffected by power factor and hence the use of power factor correction equipment would have no benefit to the customer in terms of reducing their bill. There would however be an environmental benefit through the reduction in power consumption due to reduced distribution losses. Typical reactive loads, such as transformers, lighting ballasts, and AC motors have a sinusoidal current flow, however the phase of the current waveform is shifted from that of the supply voltage waveform. Hence a poor power factor as a result of these loads can be improved via the addition of power factor correction. However, there are some loads that draw distinctly non-sinusoidal currents. Widespread offenders are the switch-mode power supplies in computers and phase controlled light dimmers. This commutation results in a discontinuous current waveform and subsequently increased losses on the supply. Not only is the current waveform highly non-sinusoidal, but it is also out of phase with the voltage supply. Inverters are also quite poor performers however some manufacturers claim a power factor of greater than 0.95 when in reality, the true power factor may be below The figure of 0.95 is based on the angle between the voltage and current waveforms but neglects that the current waveform is discontinuous and therefore contributes to increased losses on the supply. A poor power factor due to a distorted current waveform as a result of non-linear loads introducing harmonics requires harmonic filters for an appreciable improvement. Thus, detuned reactors and harmonic filters need to be included in the power factor correction equipment to reduce the possibility of resonance with the supply and to reduce the aforementioned harmonics. It is clear that any business on a kva metering tariff will benefit from power factor correction through lower electricity costs. However this may or may not be seen as an advantage depending on the payback period. For a large installation, power factor correction may cost $30,000 however may save $3000 per month in electricity costs, resulting in a pay back period of less than a year, whereas for a smaller installation the payback period may be several years and hence the capital expenditure may not be attractive to the customer. 8

12 5 Energy retailer tariff structures & requirements 5.1 Electricity Prices With the creation of the National Electricity Market (NEM) and the subsequent deregulation of electricity markets in NSW, Victoria, Queensland and South Australia, it is now possible for the vast majority of electricity customers throughout Australia to choose their retail energy supplier. As a result, customers have available to them a large number of tariff structures, a listing of which is outside the scope of this report (a listing of these retail market participants is included in Appendix B). What is more useful is a summary of average electricity prices by region, which can be related to the local Network Service Providers for those regions (although all customers may not purchase energy from their local NSP). Hence, this section outlines average energy costs for each state around Australia. The following tables list the major CBD s as well as the regional centres of Cairns, Coffs Harbour, Mt Isa, Geraldton, Alice Springs, Kalgoorlie, Charleville, Albury and Wagga-Wagga, and their associated energy retailers. Table 1 - Central Business Districts and their associated franchises (as at July 2002) Central Business District Sydney Brisbane Canberra Adelaide Perth Darwin Melbourne Hobart Franchise Energy Australia, Integral Energy Energex Actew-AGL ETSA Utilities Western Power Northern Territory Power and Water Authority (PAWA) TXU, United Energy, AGL, CitiPower, Powercor Aurora Energy 9

13 Table 2 - Regional centres and their associated franchises (as at July 2002) Regional Centre Albury, New South Wales Coffs Harbour, New South Wales Wagga Wagga, New South Wales Charleville, Queensland Cairns, Queensland Mt Isa, Queensland Kalgoorlie, Western Australia Geraldton, Western Australia Alice Springs, Northern Territory Franchise Country Energy Country Energy Country Energy Ergon Energy Ergon Energy Ergon Energy Western Power Western Power Northern Territory Power and Water Authority (PAWA) The following graphs depict average energy prices around Australia by region. Figure 5 - Average electricity retail prices by State 2001/ Note: Total average prices reflect ultimate cost to customer. Average electricity retail prices by State 2001/ /kwh NT SA VIC WA ACT QLD NSW TAS Total Average Residential Non-residential Electricity Association of Australia (ESAA) website Industry Data 10

14 Figure 6 Domestic Electricity Prices 2001/ Note: Annual consumption of 3500 kwh is representative of national average consumption. Customers in cold climatic regions may have higher consumption. Standard Domestic Tariff (with annual consumption of 3,500 kwh) /kwh (incl. GST) Western Victoria Melbourne City Melbourne-SE suburbs Eastern Victoria South Australia Tasmania Melbourne-Nth suburbs Northern Territory Western Australia Central NSW Northern NSW West Sydney-Illawarra Queensland Southern NSW Far-west NSW Canberra Sydney-Newcastle 3 Electricity Association of Australia (ESAA) website Industry Data 11

15 Figure 7 Business electricity prices 2000/ Business Electricity Prices by distribution area - high voltage demand (with annual peak demand of 2,500 kw at 60% load factor) South Australia Northern Territory Western Australia Western Victoria Canberra Far west NSW Eastern Victoria Regional Queensland /kwh (excl. GST) Northern NSW Southern NSW Central NSW Melbourne-City Melbourne-Nth suburbs Melbourne-SE suburbs Brisbane-Gold Coast West Sydney-Illawarra Tasmania Sydney-Newcastle 4 Electricity Association of Australia (ESAA) website Industry Data 12

16 5.2 Minimum Power Factor Specifications The National Electricity Code has specific provisions regarding power factors, placing the onus on market customers to manage their power factor. In particular, Schedule 5.3 Conditions for Connection of Customers sets out obligations of all classes of Customer who connect to either a transmission network or a distribution network. It represents typical requirements and particular provisions may be waived at the discretion of the Network Service Provider under the provisions of a connection agreement where such waiver would have no potential to adversely and materially affect other Code Participants. 5 S5.3.5 Power Factor Requirements 5 states: Target power factors for Customers and for distribution networks connected to another transmission network or distribution network are shown in table S5.3.1: Table 3 National Electricity Code Permissible Power Factor Ranges (Table S5.3.1) 5 Nominal Supply Voltage Permissible Power Factor Range Greater than 400 kv 0.98 lagging to unity 250 kv 400 kv 0.96 lagging to unity 50 kv 250 kv 0.95 lagging to unity Less than 50 kv 0.90 lagging to 0.90 leading A Network Service Provider may permit a lower lagging or leading power factor where this will not detrimentally affect system security, or require a higher lagging or leading power factor to achieve required power transfers. If the power factor falls outside the relevant range in table S5.3.1 over any critical loading period nominated by the Network Service Provider, the Customer must, where required by the Network Service Provider in order to economically achieve required power transfer levels, take action to ensure that the power factor falls within range as soon as reasonably practicable. Installing additional reactive plant or reaching a commercial agreement with the Network Service Provider to install, operate and maintain equivalent reactive plant as part of the connection assets may achieve this. A Code Participant who installs shunt capacitors to comply with power factor requirements must comply with the Network Service Provider's reasonable requirements to ensure that the design does not severely attenuate audio frequency signals used for load control or operations. 5 (see Ripple Control section) The following is a listing of distribution Network Service Providers (NSP s) (transmission not included) and their required minimum power factors as specified in their respective service and installation rules. 5 National Electricity Code Version 1.0 Amendment National Electricity Code Administrator Limited, ACN

17 Table 4 Distribution Network Service Providers and their Power Factor Requirements Distribution Network Service Provider State Installation Power Factor Requirements AGL Gas Company (ACT) Limited and ACTEW Distribution Limited trading as ActewAGL Distribution Australian Capital Territory All installations Min 0.9 lagging 6 EnergyAustralia New South Wales All installations Min 0.9 lagging 7 Integral Energy Australia New South Wales All installations Min 0.9 lagging 7 Australian Inland Energy and Water New South Wales All installations Min 0.9 lagging 7 Country Energy New South Wales All installations Min 0.9 lagging 7 Power and Water Authority (PAWA) Northern Territory All installations Min 0.85 lagging 8 ENERGEX Limited Queensland All installations Min 0.8 lagging Ergon Energy Corporation Limited Queensland All installations Min 0.8 lagging Utilities Management Pty Ltd (ETSA Utilities) South Australia See Table 6 South Australian Power Factor Requirements (ETSA) pg 15 Aurora Energy Pty Ltd Tasmania All installations Min 0.75 lagging to 0.75 leading 9 AGL Electricity Limited CitiPower Pty Powercor Australia Ltd TXU Electricity Limited United Energy Limited Victoria Victoria Victoria Victoria Victoria See Table 5 Victorian Power Factor Requirements (all Network Service Providers) pg 15 Western Power Corporation Western Australia All installations Min 0.8 lagging to 0.8 leading 10 6 Clause ActewAGL Service & Installation Rules 7 Clause New South Wales Service and Installation Rules 8 Power and Water Authority Service and Installation Rules 9 Section 5 Your basic responsibilities Aurora Energy Tariff Agreement 10 Clause Power Factor Requirements Western Power Access to Electricity Distribution Networks, Distribution Technical Code and Planning Criteria July

18 Table 5 Victorian Power Factor Requirements (all Network Service Providers) 11 Supply Voltage (kv) Power Factor Range for Customer Max Demand and Voltage Up to 100 kva 100 kva to 2 MVA Over 2 MVA Min. Lagging Min. Leading Min. Lagging Min. Leading Min. Lagging Min. Leading Less than , 11, Table 6 South Australian Power Factor Requirements (ETSA) 12 Supply Voltage (kv) Power Factor Range for Customer Max Demand and Voltage Up to 100 kva 100 kva to 2 MVA Over 2 MVA Min. Lagging Min. Leading Min. Lagging Min. Leading Min. Lagging Min. Leading Less than to < Greater than 66 As specified under Section S5.3.5 of the National Electricity Code 11 Table 2 Power Factor Limits Electricity Distribution Code Jan 2002 (Victoria) 12 p.14 Schedule ETSA Utilities Distribution Code 14 September

19 6 Expected and Recommended Power Factors and Maximum Loads 6.1 Recommended Power Factor As a minimum the power factor of an installation shall be in accordance with the Service Provider requirements. Where the power factor is less than this, the end-user is obligated to install power factor correction regardless. To realise cost savings within a system, consideration should be made for the power factor of an installation to be corrected as close to unity as possible. This needs to be considered in conjunction with the following major points: length of the payback period (neglecting environmental benefits). the size of the installation the electricity tariff structure the customer is on. When the size of the installation is being calculated, there will be a critical point where correcting the power factor any further will only serve to significantly increase the length of the payback period. For the vast majority of electricity Network Service Providers, the minimum power factor specified is 0.9. Correcting beyond this requirement is the payback benefit to the customer. 6.2 Where to install PFC equipment There are several different ways in which PFC equipment can be installed. PFC can be applied to separate pieces of equipment that is switched in and out as the pieces of equipment are switched on and off. The alternative to this is to bulk correct an installation by attaching the equipment to the main switchboard. There however are issues that need to be considered. If we were to take an example of a typical commercial building, the main switchboard is split into two separate sections; a house services section and a tenant section. The house section is usually on a separate bus section and is separately metered at the main switchboard and paid for by the building owner, whereas the tenant section is un-metered at the main switchboard with meters on each floor to bill each individual tenant. The house section normally houses the circuit breakers for the central air conditioning plant, lifts, house lighting and power. As will be highlighted in Section 7, motors account for a decrease in power quality and thus a reduction in power factor. In this particular instance it would be a valid exercise to consider the benefits of power factor on this section of the installation. In most instances power factor correction is installed providing immediate cost savings to the base building owner. As the tenant power is on a separate bus, they also have the opportunity to consider power factor correction. In most instances the tenant supply usually consists of general lighting and power with some supplementary air conditioning. The power factor for these installations is generally greater than 0.90 and as such there is no significant benefit in installation PFC units. In addition, these tenants are usually metered at a kwh rate that does not consider the power factor of the installation for billing purposes. In new installations, space and capacity provision for PFC equipment should be made in the main switchboard for required current transformers and circuit breakers and in the main 16

20 switchroom for the cabinets housing the equipmentregardless of whether it is to be installed initially, to allow for future installation. By connecting PFC equipment to the main switchboard, all services are generally covered and corrected. This is the easiest way to ensure maximum correction, however, depending on the size of the installation it may be more beneficial and cost-effective to apply PFC to a single piece of plant. The following provides estimates as to the expected power factors and maximum loads (VA/sqm) for the various building forms as provided in the document All Building Forms ( ). Whilst these estimates may provide an indication, the expected power factors and maximum loads depend on many factors, unique to every building including: The outside environment and its effects on the building structure Presence/absence of air-conditioning and type of system used Effects of equipment loads within the premises Lighting scheme In the ensuing tables the following headings are used: Class Building Description Expected PF VA/sqm NLA Maximum total load Savings ($) per Month the class of building as defined in the Building Code of Australia. building use any specifics relevant to the building demand rating and power factor the expected power factor for a non-corrected installation a range of the expected VA per sqm that can be expected Net Lettable Area the maximum total load that can be expected for such a building = Max VA/sqm x Floor Area (NLA) The savings that can be expected per month based on achieving a power factor of 0.95 improved from the expected power factor. The savings per month are based on a typical demand charge tariff value of $6.60/kVA/month. 17

21 ABCB Representative building forms Form A: Classes C2 F4 F2 R5 W6 G1 Building Quantities Construction ID Fabric elem. Type total FECA 10,000 m2 R5 roof rc slab w. metal deck total NLA 8,500 m2 C2 ceilings demountable tiles floors 10 W6 walls precast concrete aspect ratio 1:1 G1 glazing al frame, single glass, venetians NLA/floor 850 m2 (50% all faces) length 31.6 m F4 upper floors rc slab w ceiling depth 31.6 m F2 lowest floor suspended rc slab floor-floor 3.6 m (over basement carpark) Mid-high rise towers, covering buildings of storeys with 500-3,000 m2 per storey (total area 2, ,000 m2). Typically freestanding and seen most commonly as Class 5 in business districts (CBD or outlying centres). Classes 2 and 3 may occur in isolation in residential areas or in resorts. Parking is likely to be under the building in basements. Class Building Description Expected PF 2 Apartments VA (sqm) Maximum Total Load (kva) Savings ($) per month Aircon, electric hot water $471 Aircon, gas hot water $555 No aircon, gas hot water $236 3 Hotel Air conditioned $1,388 5 Office Tower No air conditioning $471 Air conditioning - cooling only $1,891 Reverse cycle $1,702 Electrical reheat $2,458

22 ABCB Representative building forms Form B: Classes C2 F4 R2 W6 G1 Building Quantities Construction ID Fabric elem. Type total FECA 2000 m2 R2 roof metal deck total NLA 1700 m2 C2 ceilings demountable tiles floors 3 W6 walls precast concrete aspect ratio 2:1 G1 glazing al frame, single glass, venetians NLA/floor m2 (50% N&S faces) length 36.5 m (20% E&W faces) depth 18.3 m F4 upper floors rc slab w ceiling floor-floor 3.6 m F2 lowest floor suspended rc slab (over carpark) F2 Freestanding or abutting low rise blocks (2-4 storeys) with ,000 m2 per storey (total area 1, ,000m2). In built-up areas, the buildings will mostly be aligned to the street layout and may have blank faces adjoining neighbouring buildings. May occur as freestanding buildings in regional towns, outlying centres of major cities, office park precincts or campus developments. Parking may be under the building or in adjacent surface carparks. Class Building Description Expected PF VA (sqm) Maximum Total Load (kva) Savings ($) per month 2 Apartments Aircon, electric hot water $94 Aircon, gas hot water $111 No aircon, gas hot water $47 3 Hotel Air conditioned $278 5 Office Tower No air conditioning $94 Air conditioning - cooling only $378 Reverse cycle $340 Electrical reheat $492 6 Retail Centre (air-conditioned Not air conditioned public areas $389 shops) Air conditioned public areas $605 9 Health Care/ Educational Air conditioned $567

23 ABCB Representative building forms Form C: Classes F1 R2 W6 G1 Building Quantities Construction ID Fabric elem. Type total FECA 1000 m2 R2 roof metal deck total NLA 950 m2 C2 ceiling demountable tiles floors 1 W6 walls precast concrete aspect ratio 1 G1 glazing al frame, single glass, venetians NLA/floor m2 (80% N, E&W faces) length 31.6 m (0% S face) depth 31.6 m F1 floor rc slab on ground floor-floor 6 m Freestanding, low rise blocks (1-2 storeys, totalling ,000m2) with expanded storey heights for special purposes (including retail, storage, institutional and recreational uses). Likely to occur on greenfield sites or as part of campus developments (schools, universities, hospitals, industrial precincts and technology parks) but may be found in city, town and suburban centres. Retail examples may range from freestanding single sales showrooms to fully enclosed multi-outlet developments. Parking is likely to be surface or structured facilities adjoining the buildings. Class Building Description Expected PF VA (sqm) Maximum Total Load (kva) Savings ($) per month 6 Retail sales outlets Not air conditioned $155 Air conditioned $296 7 Controlled environment Air conditioned $124 8 Storage Unventilated $0 Ventilated $0 9 Factories, workshops, Ventilated $0 auditoria, gymnasia Air conditioned $254

24 ABCB Representative building forms Form D: Classes R2 F1 W1 G1 Building Quantities Construction ID Fabric elem. Type total FECA 500 m2 R2 roof metal deck total NLA 475 m2 C2 ceiling..demountable tiles floors 1 W1 walls single leaf conc block aspect ratio 5 G1 glazing al frame, single glass, venetians NLA/floor m2 (60% N&S faces) length 50.0 m (0% E&W faces) depth 10.0 m F1 floor rc slab on ground floor-floor 3.3 m Freestanding or abutting, low rise buildings (1-2 storeys), of commercial construction (total floor areas up to 1,000 m2). Occur in most cities and towns as drive-up offices and shops with parking immediately adjoining the buildings. May also occur in campus developments and industrial precincts. Class Building Description Expected PF VA (sqm) Maximum Total Load (kva) Savings ($) per month 3 Motel $78 5 Offices No air conditioning $47 Air conditioning - cooling only $106 Reverse cycle $95 Electrical reheat $137 6 Shops Not air conditioned $78 Air conditioned $148 8 Small laboratories $26 9 Workshops, Levels 2, $85 hospital ward block Levels 5, $116 Diagnostic $155

25 ABCB Representative building forms Form E: Classes F1 R1 W4 G1 Building Quantities Construction ID Fabric elem. Type total FECA 200 m2 R1 roof concrete tiles total NLA 190 m2 C1 ceiling..sheet ceiling floors 1 W4 walls brick veneer aspect ratio 2 G1 glazing al frame, single glass, venetians NLA/floor m2 (50% N&S faces) length 20.0 m (10% E&W faces) depth 10.0 m F1 floor rc slab on ground floor-floor 3.3 m Freestanding or abutting, low rise (1-2 storeys), residential or commercial buildings of domestic construction, with in-built HVAC provisions. Individual blocks may be as small as 50 m2 but, in clusters or adjoining blocks, form facilities totalling several thousand square metres. Seen in most cities and towns as motels and residential duplexes. Parking will typically immediately adjoin the buildings. Class Building Description Expected PF VA (sqm) Maximum Total Load (kva) Savings ($) per month 2 Home units (duplex) $14 3 Hotel or motel villas Air conditioned $31 5 Offices No air conditioning $19 Air conditioning - cooling only $42 Reverse cycle $38 Electrical reheat $55

26 7 Typical Efficiencies of Electric Motors in the Building Industry This section summarises the typical efficiencies of electric motors used in the building industry and the impact of using higher efficiency motors. In Australia, more than 1.7 million three-phase electric motors run in industrial and commercial facilities, accounting for around 28 per cent of the country's electricity use. Or about 60% of electricity supplied to industry. Practically every organisation runs at least one motor if not hundreds or thousands to drive pumps, fans, air compressors, conveyors, refrigeration equipment and other processes requiring motive force. The energy consumed costs Australian industry close to $3 billion a year and produces 37 million tonnes of carbon dioxide through burning fossil fuels. Significant cost savings can be realised by utilising higher efficiency motors, especially since running costs can be up to 100 times the purchase price of a motor over its service life. 13 Motors running continuously at high loads for long periods such as exhaust fans will tend to yield the greatest savings. 7.1 Typical efficiencies Two large variables that determine the efficiency of the motor relate to both construction and operation. Motors of high quality construction have: Increased copper in the winding (up to 60%) to reduce resistance losses and operating temperatures due to the larger thermal mass Higher quality steels with an increased number of thinner laminations reduces core losses from the stator and the rotor (in an induction motor) A narrowed air gap between the rotor and stator to increase the intensity of the magnetic flux so that the same torque is available at reduced power input. Another factor that can vary over the life of the motor is operational; motor efficiency is optimised if it has been correctly sized for the job. An underloaded motor not only runs at lower efficiency but also at a lower power factor. A common way to adjust the speed of a motor is through the use of Variable Speed Drives (VSDs) or simpler two or three speed controls. VSD s are electronic systems used to control motor speed by changing the frequency and voltage supplied to the motor and can result in substantial energy savings, especially for varying loads. Small reductions in speed also can yield substantial energy savings. For example, a 20% reduction in fan speed can reduce energy consumption by nearly 50% 14. A disadvantage of VSD s however is that they are essentially large switching power supplies and hence introduce harmonics onto the supply system worsening the power factor. Power factor correction with detuned reactors however can be incorporated into these units resulting in better power quality, lower costs and reduced emissions. Controls to switch off idling motors can also save energy

27 Since 1 October 2001, three phase electric motors from 0.73kW to <185kW manufactured in or imported into Australia must comply with Minimum Energy Performance (MEPS) requirements, which are set out in AS/NZS MEPS does not apply to submersible motors, integral motor-gear systems, variable or multi-speed speed motors or those rated only for short duty cycles (IEC duty rating S2). The Minimum Energy Performance Standards (MEPS) requirements are set out as minimum efficiency levels. The following outlines the relevant sections of the Standard AS1359: Rotating electrical machines - General Requirements Part 101: Rating and Performance AS1359: Rotating electrical machines - General Requirements Part 102.1: Methods for determining losses and efficiency General AS/NZS1359: Rotating electrical machines - General Requirements Part 102.3: Methods for determining losses and efficiency Three phase cage induction motors AS/NZS1359: Rotating electrical machines - General Requirements Part 5: Three phase cage induction motors - High efficiency and minimum energy performance standards (MEPS) requirements Part 101 of AS/NZS1359 sets out methods for determining the rated output of the electric motor, thermal performance and other related performance tests (pull up torque, various short circuit tests etc.). This standard is based on and is equivalent to IEC Part (also known as Test Method B) of the standard sets out methods for determining the efficiency of an electric motor, primarily using the summation of losses for AC cage induction motors (it also covers other motor types and methods of determining efficiency). This standard is based on and is equivalent to IEC including up to amendment 2 (1996). Note that this standard assumes that additional losses (also called stray losses) are fixed at 0.5% for all motor types and sizes. Part (also known as Test Method A) of the standard sets out methods for determining the efficiency of a three phase electric motor using the summation of losses method, and includes the direct measurement of additional load losses (also called stray losses) by use of accurate torque measurements over a wide range of outputs. This standard is based on and is equivalent to US test procedures ANSI/IEEE (Method B) and NEMA MG It is also equivalent to the forthcoming edition of the revised IEC motor test procedure, which should be published by 2002/2003. Part 5 of the standard sets out the requirements for MEPS for three phase electric motors in Australia. Three phase products from 0.73kW to <185kW have to be registered for MEPS. 15 As part of AS minimum efficiency levels are set for 2, 4, 6 and 8 pole machines, according to 2 different testing methods, Test Method A (AS ) and Test Method B (AS/NZS ). These tables for Test Method A (AS ) and Test Method B (AS/NZS ) provide a very good indication to the efficiency levels of typical motors and also the efficiency improvements as motor size increases

28 Table 7 MEPS Minimum Efficiency Levels for Three Phase Electric Motors - Test Method A Rated output kw Minimum efficiency % 2 pole 4 pole 6 pole 8 pole < NOTES: 1. For intermediate values of rated output, the efficiency shall be determined by linear interpolation. 2. Tolerances specified in Table 1.1 are applicable to the above values only in the case of a verification test. 25

29 Table 8 MEPS Minimum Efficiency Levels for Three Phase Electric Motors - Test Method B Rated output kw Minimum efficiency % 2 pole 4 pole 6 pole 8 pole < NOTES: 1. For intermediate values of rated output, the efficiency shall be determined by linear interpolation. 2. Tolerances specified in Table 1.1 are applicable to the above values only in the case of a verification test. The Part 5 standard also sets out minimum efficiency levels for claims of "high efficiency" for three phase electric motors. These are set out in the tables below for Test Method A (AS ) and Test Method B (AS/NZS ): 26