Example for Electrical Distribution Architecture Design Checklist


I provide an Electrical Distribution Architecture Design Process Checklist in the previous topic “ Checklist for Electrical Distribution Architecture Design ".

Today, I will introduce a solved Example for Electrical Distribution Architecture Design Process Checklist as follows.


For good following, you can review the next previous topics:





Example for Electrical Distribution Architecture Design Process Checklist


By using this Checklist, you will be able to list all the characteristics, factors and conditions that affect the design of the power architecture design (single line diagram) for any project.

What you need to do is putting (√ ) in the check box in front of the right choice , the previous topics listed above will help you for determining the right choice and you can review them for this purpose.

This solved example shows how to use the Electrical Distribution Architecture Design Process Checklist for designing and drawing an optimal single line diagram for the project under study.


And here is the example: 

Project name: electrical installation in a printworks building. 


And The Checklist will be as follows: 

Checklist For Application Of Electrical Distribution Architecture Design Process
Brief Description: Printing of personalized mail shots intended for mail order sales.
First: Assigning Of Electrical Installation Characteristics
#
Characteristic
√
Choice
1
Activity
√
Industrial Buildings 

Commercial Buildings 

Residential Buildings 

Agricultural Buildings 

Educational Buildings 

Transportation Buildings 

Religious Buildings 

Parking And Storage 

Military Buildings 

Governmental Buildings 

Cultural Buildings 

Other Buildings
2
Site Topology
√
Single Storey Building,(Low Rise) 10000m² (8000m² dedicated to the process, 2000m² for
ancillary areas)

Multi-Storey Building, ,(Low Rise)

Multi-Building Site,

High-Rise Building
3
Layout Latitude

Low (≤ 2,500 m2)

Medium (2,000 m2- 2,500 m2)
√
High (> 2,000 m2)
4
Service Reliability

Minimum
√
Standard

Enhanced
5
Maintainability

Minimum
√
Standard

Enhanced
6
Installation Flexibility
√
No Flexibility :for HVAC
, Process utilities
and Office power supply
√
Flexibility Of Design: finishing, putting in envelopes special machines, installed at a later date
and rotary machines (uncertainty at the draft design stage)

Implementation Flexibility

Operating Flexibility
7
Power  Demand

< 630 kVA

630 – 1250 kVA

1250 -  2500 kVA
√
> 2500 kVA ( = 3500kVA)
8
Load Distribution

Uniform Distribution
√
Intermediate Distribution

Localized Loads
9
Power Interruption Sensitivity
√
“Sheddable” Circuit : offices (apart from PC power sockets), air conditioning, office heating
, social premises and maintenance premises
√
Long Interruption Acceptable : printing machines, workshop HVAC (hygrometric control)
, Finishing, envelope filling and Process utilities (compressor, recycling of cooled water)

Short Interruption Acceptable
√
No Interruption Acceptable : servers and office PCs
10
Disturbance  Sensitivity

Low Sensitivity
√
Medium Sensitivity :motors and lighting
√
High Sensitivity : IT , No special precaution to be taken due to the connection to
the EdF network (low level of disturbance)
11
Disturbance Capability  Of Circuits
√
Non Disturbing

Moderate Or Occasional Disturbance

Very Disturbing
12
Other Considerations Or Constraints
√
Environment : Building with lightning classification: lightning surge arresters installed

Specific Rules
√
Rule Of The Energy Distributor : Power supply by overhead single feeder line

Attachment Loads

Load Power Supply Constraints
Second: Assigning Of Technological Characteristics
1
Environment And Atmosphere
√
Standard (IP,IK,C°) : IP (no dust, no water protection),   IK:  (use of technical pits, dedicated premises) and °C:  (temperature regulation)

Enhanced (IP,IK,C°)

Specific (IP,IK,C°)
2
Service Index

111
√
211

223

232

233

332

333
3
Other Considerations

Designer Experience

Utilities Requirements

Specific Technical Criteria
Third: Using Architecture Assessment Criteria
1
On-Site Work Time
√
Secondary

Special

Critical
2
Environmental  Impact

Non significant
√
Minimal: compliance with European standard regulations

Proactive
3
Preventive Maintenance Level
√
Standard

Enhanced

Specific
4
Availability Of Electrical Power Supply
√
Availability Level = 1
Forth: Step (1): Choice Of Distribution Architecture Fundamentals
1
Connection To The Upstream Network

LV Service
√
MV Single Line Service (Isolated site)

MV Single Line- One Substation - One Ring Main Unit Service

MV Double Line - One Substation - Double Ring Main Unit - One Loop Service

MV Duplicate Supply Service,

MV Duplicate Supply Service With Double Busbar.
2
MV Circuit Configuration
√
Single Feeder, One Or Several Transformers (Layout + criticality)

Open Ring, One MV Incomer

Open Ring, 2 MV Incomers
3
Number And Distribution   Of MV/LV Transformation Substations
√
 1 Substation With N Transformers  (NO link between MLVS)
√
N Substations With N Transformers (Identical Substations) (If Power >2500KVA) (interconnected switchboards)

N Substations With M Transformers (Different Powers) (If Power >2500KVA) (For Several Buildings)
4
Number Of MV/LV Transformers
√
2  Transformersx 2000kVA because Power > 2500kVA

The Number Of Transformers (= 1) (If Power < 1250 KVA)
5
MV Back-Up Generator

Yes (Site Activity - Total Power Of The Installed Loads - Sensitivity Of Circuits To Power Interruptions -Availability Of The Public Distribution Network)
√
No




 please Note that:
Characteristic# 3 in step (1) gives 2 possible solutions as follows:

  • Solution#1: (building area < 25000 m2 but power demand > 2500KVA) so, we can use (1) Substation which include two Transformers (as determined by chara. # 4 in step (1) above). 
  • Solution#2: (building area < 25000 m2 and power demand > 2500KVA) so, we can use (2) Substation remote from each other, each include (1) Transformers. 

And both solutions come with MV circuit configuration as indicated in Characteristics# 1 & 2 in step (1) above: MV Single Line Service with MV circuit as single feeder.

So, the single line diagram for the MV Part and MV/LV substations will be as in fig.1.


Fig.1

Then, let’s complete the checklist for determining and drawing the LV part of the single line diagram for this project as follows:

#
Characteristic
√
Choice
Fifth: Step (2): Choice Of Architecture Details
1
Layout

Place power sources as close as possible to the barycenter of power consumers,
√
Reduce atmospheric constraints: building dedicated premises

Placing heavy equipment (transformers, generators, etc) close to walls or main exists for ease of maintenance,
2
Centralized Or Distributed Layout
√
Centralized Layout : finishing sector and envelope filling
√
Decentralized Layout : special machines, rotary machines, HVAC, process utilities, offices (2 switchboards), office air conditioning, social premises and maintenance
3
Presence Of Back-Up Generators

Yes (Sensitivity of loads to power interruption, Availability of the public distribution network)
√
No (Criticality ≤ low and Network availability: standard)
4
Presence Of An Uninterruptible Power Supply (UPS)
√
Yes (Criticality: UPS unit for servers and office PCs)

No
5
Configuration Of LV Circuits

Radial single feeder configuration

Two-pole configuration
√
Variant: two-pole with two ½ MLVS + No link (2 transformers, possible partial redundancy)
√
Shedable switchboard (for noncritical loads)

Interconnected switchboards

Ring configuration

Double-ended power supply

Configuration combinations


you can note the following:

From characteristics# 1 to 5 in step (2) above and from the (2) solutions we got from step (1), the LV Part of the single line diagram will be one of the following:

  • For solution# 1 from step (1): the LV circuit configurations will be as (2) Half MLVS (Main Low Voltage Switchboard) and no (open) Link. (See fig.2).


Fig (2)

  • For solution# 2 from step (1): the LV circuit configurations will be as (2) MLVS (Main Low Voltage Switchboard) remote from each other and connected as interconnected switchboards by busbar trunking. (See fig.3).
Fig (3)


So, the complete single line diagram will be either fig (2) or fig (3) and to select one of them you must use step (3): Choice of MV/LV Equipment and apply recommendations For Architecture Optimization: enhancements to designed single line diagrams as follows:


#
Characteristic
√
Choice
Sixth: Step (3): Choice Of MV/LV Equipment (Atmosphere, Environment, IP, IK - Service Index - Offer Availability Per Country - Utilities Requirements )
1
MV/LV substation
√
indoor (dedicated premises)
2
MV switchboard
√
SM6 (installation produced in France)
3
Transformers
√
cast resin transfo (avoids constraints related to oil)
4
LV switchboard
√
MLVS: Prisma + P Sub-distribution: Prisma +
5
Busbar trunking
√
Canalis KS
6
UPS units
√
Galaxy PW
7
Power factor correction
√
LV, standard, automatic (Average Q, ease of installation)
Seventh: Recommendations For Architecture Optimization
1- Use of proven solutions and equipment that has been validated and tested by manufacturers (“functional” switchboard or “manufacturer” switchboard according to the application criticality)
2- Prefer the implementation of equipment for which there is a reliable distribution network and for which it is possible to have local support (supplier well established)
3- Prefer the use of factory-built equipment (MV/LV substation, busbar trunking) allowing the volume of operations on site to be limited
4- Limit the variety of equipment implemented (e.g. the power of transformers)
5- Avoid mixing equipment from different manufacturers.
6- Appropriate metering and analysis of loads actual consumption
7- Power factor correction solutions
8- Appropriate organisation and design of site and use of busbar truncking instead of cables wherever accurate
9- Reducing the length of LV circuits in the installation by Placing MV/LV substations as close as possible to the barycenter of all of the LV loads to be supplied
10- Clustering LV circuits wherever possible to take advantage of the factor of simultaneity ks  by:
a- Setting up sub-distribution switchboards as close as possible to the barycenter of the groups of loads if they are localized
b- Setting up busbar trunking systems as close as possible to the barycenter of the groups of loads if they are distributed.
11- Focus maintenance work on critical circuits,
12- Standardize the choice of equipment,
13- Use equipment designed for severe atmospheres (requires less maintenance).
14- Reduce the number of feeders per switchboard, in order to limit the effects of a possible failure of a switchboard
15- Distributing circuits according to availability requirements
16- Using equipment that is in line with requirements (SI index)
17- Follow the selection guides proposed for steps 1 & 2
18- Change from a radial single feeder configuration to a two-pole configuration,
19- Change from a two-pole configuration to a double-ended configuration,
20- Change from a double-ended configuration to a uninterruptible configuration with a UPS unit and a Static Transfer Switch
21- Increase the level of maintenance (reducing the MTTR, increasing the MTBF)




In the next topic, I will explain the software program ID-Spec for design Electrical Distribution Architecture. So, please keep following.


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