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Information: Electrical Design Information for Distribution Networks: After Diversity Maximum Demand

Standard Number: HPC-3DC-07-0001-2012

DM# 3666669 Page 2 of 13 Print Date 11/07/2013

© Horizon Power Corporation – Document Number: HPC-3DC-07-0001-2012

Uncontrolled document when printed. Printed copy expires one week from print date. Refer to Document No. for current version.

Document Control

Author Name: Anthony Seneviratne

Position: Senior Standards Engineer

Document Owner

(May also be the Process Owner)

Name: Justin Murphy

Position: Manager Asset & Works

Approved By * Name: Justin Murphy

Position: Manager Asset & Works

Date Created/Last Updated April 2013

Review Frequency ** 3 yearly

Next Review Date ** April 2016

* Shall be the Process Owner and is the person assigned authority and responsibility for managing the whole process, end-to-end, which may extend across more than one division and/or functions, in order to deliver agreed business results.

** Frequency period is dependent upon circumstances– maximum is 5 years from last issue, review, or revision whichever is the latest. If left blank, the default shall be 1 year unless otherwise specified.

Revision Control

Revision Date Description

1 15/04/2013 Initial Document Creation

STAKEHOLDERS The following positions shall be consulted if an update or review is required:

Manager Engineering Services

Manager Engineering Systems Planning

Manager Assets and Works




TABLE OF CONTENTS

1 PURPOSE .................................................................................................... 4

2 APPLICATION ............................................................................................. 4

3 GENERAL .................................................................................................... 4

3.1 Definitions and Abbreviations ................................................................................. 4

3.2 Related Information ................................................................................................ 5

4 AFTER DIVERSITY MAXIMUM DEMAND (ADMD) ..................................... 5

4.1 What is ADMD ........................................................................................................ 5

4.2 Regional values of ADMD ....................................................................................... 5

4.3 Standard Supply to Customer Installations ............................................................. 7

4.4 Diversity Factors ..................................................................................................... 7

4.5 Application of ADMD values ................................................................................... 8

4.5.1 Distribution Substation Network Planning .............................................................................. 8

4.5.2 LV Design Computer Program ................................................................................................ 8

APPENDIX A – REVISION INFORMATION .......................................................................... 9

APPENDIX B – STANDARD CUSTOMER SUPPLIES ........................................................ 10

APPENDIX C – UNDERSTANDING ADMD VALUES ......................................................... 12

APPENDIX C.1 Examples using the Equation in section 4.5.1 ......................................... 12

APPENDIX C.2 LV Distribution feeder network planning .................................................. 13




1 PURPOSE

This Standard outlines the after diversity maximum demand (ADMD) electrical loading values to be used when carrying out overhead and underground distribution network design for various customer classes within Horizon Power’s area.

The ADMD values have taken into account seasonal climatic, locational and community factors to ensure that adequate capacity is installed for the normal life of Horizon Power’s electrical network assets while ensuring statutory requirements and customer expectations are met in a cost effective manner.

2 APPLICATION

Whenever design work is carried out to construct new network assets, decisions are required as to the electrical loads that shall be used in order to satisfy both customer and/or network requirements in the most cost effective manner.

The values of after diversity maximum demand to be used at a customer level have been based on assessments of load growth patterns experienced in Horizon Power’s regional areas, together Western Australian statutory requirements.

3 GENERAL

3.1 Definitions and Abbreviations

ADMD means after diversity maximum demand, and is expressed as the simultaneous maximum electrical demand of a group of customers divided by the number of customers, expressed in kilovolt amperes

Coincidence Factor

the ratio of the simultaneous maximum electrical demand of a group of customers within a specified period to the sum of their individual maximum demands within the same period, expressed as a numerical value or percentage

Diversity Factor (DF)

The ratio of the sum of the non-simultaneous maximum demands of a number of customers divided by the simultaneous maximum demand of the network/system suppling the customers, expressed as a numerical value of percentage.

Maximum Demand

The average value of the greatest apparent power (kVA) over a five minute period.




3.2 Related Information

Requirements and Information relating to this document may be found within the source documents detailed below:

1) Western Australian Electrical Requirements (WAER)

2) Horizon Power’s Western Australian Distribution Connections Manual (WADCM)

3) Horizon Power’s Maximum Transformer Sizes for non-interconnected Systems

4) Australian Standard AS 3000-2007 Wiring Rules

4 AFTER DIVERSITY MAXIMUM DEMAND (ADMD)

4.1 What is ADMD

ADMD is the basic electrical load, on a per customer basis, used for the design of Horizon Power’s electrical network. It represents the maximum demand, calculated for a distribution substation, where there are more than 60 customers in total connected to that substation. Where there are less than 60 customers, diversity is used to estimate maximum demand.

ADMD is normally expressed as kVA per customer, although Amperes per customer can also be used where appropriate.

ADMD represents the electrical load:

1) At a distribution substation where there are 60 customers or more connected to the substation.

Where there are less than 60 customers per substation, a “diversity factor” can be applied that modify the ADMD to determine design values of substation maximum loads and subsequent decisions on substation sizes and locations.

2) On a low voltage distribution feeder, when modified by a “diversity factor”, that is used to calculate the feeder voltage drop to ensure all customers receive electricity supply within the Standard Supply voltage limits of 240 V ac ±6%.

4.2 Regional values of ADMD

Values of ADMD to be used within Horizon Power’s Regional urban areas are shown in Table 1.

The design ADMD values are based on measured ADMD values with an allowance made for potential growth over the life of the cable asset.

This allowance reflects the range of climatic zones, socio-economic and expansion potential factors applicable in each town, and can be influenced by but not limited to:

1. Propensity for growth in residential housing where the energy consumption will be heavily subsidised due to resource sector growth;

2. Increasing affordability to use air conditioning and other electrical appliances with corresponding uptake of these facilities; and




3. Change in the socio-economic demographics in regional areas.

The allowance adopted to be added to the measured ADMD to obtain the design ADMD is based on a combination of design experience, cost impact analysis and the need for a standardised approach. (Refer to DM# 3389478, 2093275 and 2172159)

The design ADMD values shall be used in all new designs.

Table 1: - List of ADMD’s for towns

Towns Residential ADMD

(kVA)


(kVA)

East Kimberley

Halls Creek 6 Lake Argyle 6

Kalumburu 6 Warmun 4

Kununurra 6 Wyndham 6

West Kimberley

Ardyaloon 4 Derby 6

Beagle Bay 4 Djarindjin/Lombadina 4

Bidyadanga 4 Fitzroy Crossing 6

Broome 6 Yungngora 4

Camballin/Looma 4

East Pilbara

Marble Bar 4 Port Hedland (Note 1) 10

Nullagine 4 South Hedland (Note 1) 10

West Pilbara

Karratha – Single lot 10 Onslow 10

- Duplex 7.5 Point Samson 10

- Triplex 5.5 Roebourne 6

- Quadr’ex 3.5

Gascoyne/Midwest

Carnarvon 6 Meekatharra 6

Coral bay 6 Menzies 6

Cue 6 Mt Magnet 6




Denham 4 Sandstone 4


(kVA)


(kVA)

Exmouth 6 Wiluna 4

Gascoyne Junction 4 Yalgoo 4

Laverton 6

Leonora 6

Esperance

Esperance 3 Norseman 3

Hopetoun 3

Note 1: Where multiple occupancy lots are developed in towns with ADMD of 10 kVA, the corresponding ADMD values shown for Karratha shall apply.

4.3 Standard Supply to Customer Installations

The Western Australian Distribution Connections Manual (WADCM) provides details of the “Standard Supply” that is normally provided for single dwelling, residential customers, as shown below. For some locations within Horizon Power, due to limits in either local generation capacity or generator step load response, customer “Standard Supply” load values lower than those specified in the WADCM may be applicable.

4.4 Diversity Factors

Diversity factors have been determined throughout Horizon Power’s Regions and are typically as shown below. When the “LV Design” software is used for network design, the following appropriate diversity factors have already been incorporated into the calculations.




Table 2: - Diversity Factors

No of customers Diversity factor No of customers Diversity factor

1 3.0 10 1.64

2 2.57 11 1.61

3 2.2 12 -14 1.57

4 2.0 15-17 1.50

5 1.89 18-20 1.46

6 1.8 21-23 1.42

7 1.74 24-26 1.4

8 1.71 27-29 1.38

9 1.69 30-59 1.37

≥60 1.0

4.5 Application of ADMD values

4.5.1 Distribution Substation Network Planning

The ADMD allows the electrical network to be planned and constructed to meet current customer loads as well as making reasonable provision for future customer load growth by determining the design maximum demand to be used, in accordance with the equation below.

Where:

MD is the Maximum Demand in kVA or Amps

N is the Number of Customers connected

DF is the Diversity Factor (see Table 2)

ADMD is the After Diversity Maximum Demand in kVA or Amps

4.5.2 LV Design Computer Program

The values calculated for ADMD above shall be used as input data to the program.




APPENDIX A – REVISION INFORMATION

(Informative) Horizon Power has endeavoured to provide standards of the highest quality and would appreciate notification if any errors are found or even queries raised.

Each Standard makes use of its own comment sheet which is maintained throughout the life of the standard, which lists all comments made by stakeholders regarding the standard.

A comment sheet found in DM: 3537105, can be used to record any errors or queries found in or pertaining to this standard, which can then be addressed whenever the standard gets reviewed.

Date Rev No. Notes

15/04/2013 1 First Issue




APPENDIX B – STANDARD CUSTOMER SUPPLIES

Horizon Power Regional Non-Interconnected Towns

Location Maximum

Single phase supply

Maximum Three phase

supply (per phase)

Maximum Motor size

(3 phase DOL)

Ardyaloon 32 A 15 A 3 kW

Beagle Bay 32 A 15 A 3 kW

Bidyadanga 32 A 15 A 3 kW

Broome 63 A 32 A

Camballin/Looma 32 A 15 A 3 kW

Point Samson 63 A 32 A

Carnarvon 63 A 32 A

Coral Bay 32 A 15 A 3 kW

Cue 32 A 15 A 3 kW

Dampier 63 A 32 A

Denham 32 A 15 A 3 kW

Derby 32 A 15 A 3 kW

Esperance Town 63 A 32 A

Esperance Rural Refer to the Esperance District Office

Exmouth 32 A 15 A 3 kW

Fitzroy Crossing 32 A 15 A 3 kW

Gascoyne Junction 32 A 15 A 3 kW

Halls Creek 32 A 15 A 3 kW

Hopetoun 32 A 15 A 3 kW

Hopetoun Rural Refer to the Esperance District Office

Kalumbaru 32 A 15 A 3 kW

Karratha 63 A 32 A

Kununurra 63 A 32 A




Location Maximum

Single phase supply

Maximum Three phase

supply (per phase)

Maximum Motor size

(3 phase DOL)

Lake Argyle 32 A 15 A 3 kW

Laverton 32 A 15 A 3 kW

Leonora 32 A 15 A 3 kW

Lombadina/Djarindjin 32 A 15 A 3 kW

Marble Bar 32 A 15 A 3 kW

Meekatharra 32 A 15 A 3 kW

Menzies 32 A 15 A 3 kW

Mount Magnet 32 A 15 A 3 kW

Norseman 32 A 15 A 3 kW

Nullagine 32 A 15 A 3 kW

Onslow 32 A 15 A 3 kW

Port and South Hedland 63 A 32 A

Roebourne 63 A 32 A

Sandstone 32 A 15 A 3 kW

Warmun 32 A 15 A 3 kW

Wiluna 32 A 15 A 3 kW

Wyndham 32 A 15 A 3 kW

Yalgoo 32 A 15 A 3 kW

Yungngora 32 A 15 A 3 kW




APPENDIX C – UNDERSTANDING ADMD VALUES

APPENDIX C.1 Examples using the Equation in section 4.5.1

a) Evaluate the size of the distribution substation to be installed.

Example 1: A subdivision consists of 60 residential lots in Karratha (ADMD=10 kVA).

Option 1: Install one substation

Total load (kVA) = 60 (cust.) x 1 (DF) x 10 kVA (Karratha ADMD)

= 600 kVA [Note DF = 1, as N = 60)

Recommendation: Install 1 x 630 kVA substation, subject to:

LV Design program validating an effective LV distribution network can be installed. Substation should be sited centrally so that all LV feeders are of the same circuit length.

Option 2: Install two substations (e.g. where one substation cannot satisfy site physical constraints).

Total load (kVA) per substation 1= 20 x 1.46 x 10 kVA = 292 kVA [DF = 1.46 for N = 20)

Total load (kVA) per substation 2= 40 x 1.0 x 10 kVA = 400 kVA [DF = 1.0 for N = 40)

Recommendation: May need to install 1 x 315 kVA substation and 1 x 630 kVA substation at a different location, subject to LV Design program validating an effective LV distribution network.

Example 2: A subdivision consists of 18 residential lots in Denham (ADMD=8 kVA). The subdivision is constrained and future adjacent development will not occur.

For installation of one substation (based on alternative LV interconnections with existing substations being available).

Total substation load (kVA) = 18 x 1.46 x 8 kVA = 210 kVA [DF = 1.46, for N =18)

Recommendation: Install 1 x 315 kVA substation, subject to:

LV Design program validating an effective LV distribution network. Substation should be sited centrally so that all LV feeders are of the same circuit length

Transformer size not exceeding maximum size specified in HP document “Maximum transformer sizes for non-interconnected systems” – DM# 3463822.

b) Evaluate the maximum number of customers per distribution substation.

Example 3: 630 kVA MPS installation as part of a residential subdivision consisting of 250 lots in Broome (ADMD=6 kVA).

From MD = N x DF x ADMD




Number (N) = MD/(ADMD X DF) = 630/(6 X 1) = 105 customers (DF = 1, as N > 60)

Example 4: 315 kVA substation as part of an expanding residential subdivision in Derby.

From MD = N X DF X ADMD

Trial a value of N (based on 30 cust.)

N = MD/(ADMD X DF) = 315/(8 X 1.37) = 28 customers (based on DF = 1.37 for N =30)

Retrial with N = 28 customers)

N = MD/(ADMD X DF) = 315/(8 X 1.38) = 28 customers (based on DF = 1.38 for N =28)

APPENDIX C.2 LV Distribution feeder network planning

Again the ADMD allows the LV distribution network to be planned and constructed to meet current customer loads as well as making reasonable provision for future customer load growth by determining the design maximum demand to be used, in accordance with Equation 1 above.

Example 5: A 630 kVA substation in an Esperance residential subdivision will have 4 LV circuits installed. Two circuits will have 18 customers each, one will have 15 customers, one will have 12 customers.

What is the maximum current rating for each feeder circuit at the substation?

Feeder circuits 1 & 2: 18 customers each

Maximum load per circuit = 18 (cust) x 8 kVA (ADMD) x 1.46(DF)

= 210 kVA = 292 Amps [= 16.2 A/customer]

Feeder circuits 3: 15 customers

Maximum load per circuit = 15 (cust) x 8 kVA (ADMD) x 1.5 (DF)

= 180 kVA = 250 Amps [= 16.7 A/customer)

Feeder circuits 4: 12 customers

Maximum load per circuit = 12 (cust) x 8 kVA (ADMD) x 1.57 (DF)

= 151 kVA = 210 Amps [= 17.5 A/customer)

The effect of diversity factor on individual LV distribution circuits is demonstrated by a comparison of the average load/customer in the above three cases, where average load per customer (i.e. Amps/customer), measured at the distribution substation LV switchboard, increases as the number of customers on the circuit decreases.

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Information: Electrical Design Information for ... · PDF fileDistribution Networks: After Diversity Maximum ... 4.5.1 Distribution Substation Network Planning ... No of customers