P1

VOLTAGE & EQUIPMENT STANDARDS

MISALIGNMENT

The nominal voltage in Australia has been 240 volts from about 1926 until 2000 when it was changed to 230 volts to align with

international standards. This change was made to improve the economics of manufactured appliances by manufacturers having

to design and build products to operate across only one voltage range. This paper details some major issues of discord between

the present state-based voltage requirements, Australian Voltage Standard and product standards.

By Chris Halliday - Electrical Consulting and Training Pty Ltd and Dave Urquhart - Energex

Introduction

The nominal voltage in Australia had beenset at 240 volts since about 1926. In 1980,the International ElectrotechnicalCommittee (IEC) decided to rationalise the220, 230 and 240 volt nominal voltage levelsto a consistent 230 volt standardinternationally. This rationalisation wasallegedly made to improve the economics ofmanufactured appliances by allowingmanufacturers to produce appliances withonly one rated voltage – 230 volts. In 1983,the IEC issued the sixth edition of its voltagestandard IEC60038 which adopted 230/400volts ±10% as the new internationalstandard distribution voltage with a further4% voltage drop within electricalinstallations. Countries such as Australia thathad a nominal 240 volt system were to havea lower limit of 230-6% at the point ofsupply.

Standards Australia issued AS 60038 in 2000with 230 volts as the nominal voltage with a+10%, -6% range. AS/NZS 3000 Wiring Rulesstill allows a 5% voltage drop withinelectrical installations. New Zealand has arange of ±6% and the further 5% allowed bythe Wiring Rules. Figure 1 shows acomparison of the voltage range in Australiaunder the old 240 volt standard (AS2926),the range prescribed by the currentStandard in Australia and the 230 +/- 6%range that has existed in New Zealand(Electrical (Safety) Regulations 2010) forsome time.

Some states of Australia have been slow toadopt the new 230 volt standard althoughthey haven’t changed the way they operatetheir network except to use the increasedlower level to defer augmentation work. Inother states, such as Queensland, the 240+/-6% voltage range is mandated in theirElectricity Act - this conflicts with the rangeprescribed under the Australian Standard.

This paper seeks to detail some of the issuesof discord between the different state basedrequirements and voltage and productstandards. It does not analyse the logic

P2

behind the move to a nominal 230 voltstandard, the effect on 240 voltappliances of widening the allowablevoltage range at the lower end of therange or the efficiency of equipment overthe full utilisation voltage range (thevoltage range at the outlets or at theterminals of equipment).

Standards and State BasedRequirementsTable 1 details the various voltage levelrequirements of each state in Australia bynetwork company and that of NewZealand. It can be seen that there is a lackof consistency between the voltage levelsand the ranges of voltage, particularly inAustralia.

Equipment StandardsTable 2 sets out the differences in rateddesign voltage and operating ranges, asset out in a sample of AustralianStandards, for various equipment classes.Figure 2 graphically highlights thesedifferences.

Analysis and Design Options forEquipmentIt is clear from Table 1 that there is noconsistency in the way the Australianvoltage standard is applied by thedifferent states. There is also conflictbetween the range of voltages defined inthe Standard and the Electricity Act insome states. Therefore, there needs to beagreement on the allowable voltagerange. The finalising and adoption by allAustralian states of the now draftAustralian and New Zealand StandardAS/NZS61000.3.100 would seem to bethe logical way of achieving consistency.

Figure 2 clearly shows that there is a gapbetween equipment design requirementsas determined by Australian Standardsand the Australian voltage Standard. Areduction in the Wiring Rules’ allowablevoltage drop within electrical installationsto 4% (in line with international practice)would help to narrow the gap for some ofthe equipment detailed in Figure 2 andprovide greater consistency withinternational standards. Thisrecommendation does not considerwhether the increased cost within aninstallation is justified when compared tothe reduced losses and the cost ofmanufacturing appliances to operate overa wider voltage range.

The most significant equipmentincompatibility with the range of voltageis for motors. From the AustralianStandard (AS/NZS60034.1), motors are tooperate within ±5% of 230 volts (Zone A –see Figure 2). Motors can operate withinZone B, (the range widen to ±10% - seeFigure 2) but this relies on motors

generally being underrated for the workbeing performed with excursions into thiszone limited in value, duration andfrequency of occurrence. Essentially, fullyloaded motors designed only to theAustralian Standard will not cope with therange of voltages allowed withinAustralia. Even for lightly loaded motorsthere is a compatibility gap evident at thebottom of Zone B as the lower utilisationvoltage limit is below the designrequirements for Zone B.

Electronics could be installed on the frontend of all motors to ensure motors couldcope with the full range of voltage butthis would cause unnecessary expenseespecially given that not all sites receivevoltage towards the outer extremities ofthe distributor’s allowable voltage rangeand that not all installations fully utilisethe allowable 5% voltage drop. Motorsare presently available with variousnominal voltages and voltage ranges

specified and it is the responsibility of thedesigner and/or installer to choose amotor that can cope with the allowablevoltage range or fit a variable speed driveto the motor.

There is also a major compatibility issuewith lighting, as AS/NZS60589.1 specifiesa range of 240 volts ±10%. Electronicballasts are still not often used in largerwattage light fittings, such as is used forstreet or sport field lighting. Light outputis very dependent on voltage in thesesorts of lights, and consequently lightingdesign needs to take voltage levels intoconsideration to ensure light levels meetsthe requirements of the AustralianStandards. Electronic ballasts capable ofoperating efficiently over wider voltageranges are becoming more common forsmaller wattage lights.

Using electronics to control voltage tomany types of heating appliances is a cost

Figure 2 – Graphical Representation of Voltage Requirements for Various Types of Equipment

P3

effective way of coping with the fullallowable voltage range. For stoves, theelement could be designed to workefficiently on the lower end of the voltagerange and the controller couldincorporate electronic voltage control tothe element instead of the moretraditional simmerstat. The same couldbe said for toasters, fan heaters, etc. Thiswould add minimal cost to the initialpurchase price, but would improvetemperature control and efficiency.Heating appliances such as electricblankets, hot water systems, bar heaters,jugs and electric oil heaters/radiators willsimply take longer to heat up at lowervoltages. These should therefore bedesigned for the highest allowablevoltage.

Clearly the discord between applianceand voltage standards as highlighted inTable 2 and Figure 2 needs to beresolved.

Minimum Energy PerformanceStandards (MEPS)A sample of Australian/New ZealandStandards for MEPS for various classes ofequipment were investigated to see whatvoltage is specified for testing for the starrating for the equipment. It was foundthat the test voltage is maintained with±2% of the rated voltage for the majorityof tests across the various types ofequipment (refer Table 3 for more detail).

This may mean that a piece of equipmentwith a low star rating may actuallyperform better at the extremities of the230 volt utilisation voltage range thanbetter star rated equipment. It alsomeans that the MEPS rating ismeaningless for most equipmentconnected to the typical voltagesAustralian distributors are currentlydelivering.

Conclusions

Requirements for voltage and voltage

range needs to be consistent across

Australia. The Australian National

Electricity Rules (NER), rather than state-

based regulation, needs to specify

requirements for voltage in Australia. This

could be achieved by defining the

required standard in the NER.

A major overhaul of Australian equipment

standards is recommended with all

standards nominating the rated supply

voltage as 230 volts with an operating

range of ±10%. All equipment nameplates

should specify the nominal voltage and

effective operating range. Consistency is

required within Australian/New Zealand

MEPS standards and the star rating needs

to provide a proper indication of

equipment performance over the full

utilisation voltage range.

The Wiring Rules allowable voltage drop

should be reduced from 5% to 4% to align

with international standards and to allow

equipment to operate more effectively.

Manufacturers will need to consider the

design of their products to achieve the

requirements of any revised equipment

standard and to operate over the

allowable voltage range. Harmonics will

need to be managed by careful design of

equipment to ensure trouble free

operation of the equipment and to

prevent more widespread problems.

To discuss this matter further contact:

Chris Halliday: chris@elect.com.au

or

Dave Urquhart:

Daveurquhart@energex.com.au