In the previous Topic “ The Electrical Distribution Architecture – Part Two “ , I list the Tasks required for application of Electrical Distribution architecture design process , they were:
- Assigning of electrical installation characteristics,
- Assigning of Technological characteristics,
- Using Architecture assessment criteria,
- Step (1): Choice of distribution architecture fundamentals,
- Step (2): choice of architecture details,
- Step (3): choice of equipment,
- Recommendations for architecture optimization.
And I began explaining the first task: Assigning of electrical installation characteristics which include the following categories or possible values:
- Activity,
- Site topology,
- Layout latitude,
- Service reliability,
- Maintainability,
- Installation flexibility,
- Power demand,
- Load distribution,
- Power Interruption Sensitivity,
- Disturbance sensitivity,
- Disturbance capability of circuits,
- Other considerations or constraints.
Today, I will continue explaining other tasks for helping you to use Electrical Distribution architecture design process professionally.
You can review the following previous topics for more information and good following:
5- Maintainability
#
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characteristic
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Definition
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choice
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5
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Maintainability
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Features input during
design to limit the impact of maintenance actions on the operation of the
whole or part of the installation.
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Minimum: the installation must be stopped to carry out maintenance
operations.
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Standard: maintenance operations can be carried out during installation
operations, but with deteriorated performance. These operations must be
preferably scheduled during periods of low activity.
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Enhanced: special measures are taken to allow maintenance operations
without disturbing the installation operations.
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The Maintainability level is determined to be (minimal, standard and enhanced) based on the following factors:
- The Activity importance of the building.
- The site topology of the building.
- The power demand of the building.
The following table summarizes the effect of these factors on the Maintainability level and fig (1) represents the Configuration of Electrical Distribution Architecture in each case:
Characteristic
To Consider
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Configuration
of Electrical
Distribution Architecture (Supply side of Transformers)
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LV
(No Transformers)
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MV
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Single-Line / Single Feeder
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Ring-Main
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Duplicate Supply / Open Ring 1 MV Substation
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Duplicate Supply With Double Busbars / Open Ring 2 MV
Substations
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Activity
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Any
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Any
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Any
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Hi-tech, sensitive Office, Health-Care
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Any
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Site
Topology
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Single Building
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Single Building
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Single Building
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Building With One Level or
Several Buildings
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Several
Buildings
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Power
Demand
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<
630kva
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≤
1250kva
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≤
2500kva
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>
2500kva
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>
2500kva
|
Maintainability
|
Minimal
|
Minimal
or Standard
|
Standard
|
Enhanced
|
Enhanced
|
 |
| Fig (1): Configuration Of Electrical Distribution Architecture (Supply side of Transformers) |
6- Installation flexibility
#
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characteristic
|
Definition
|
choice
|
|
6
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Installation Flexibility
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Possibility of easily moving
electricity delivery points within the installation, or to easily increase
the power supplied at certain points. Flexibility is a criterion which also
appears due to the uncertainty of the building during the pre-project summary
stage.
Examples:
- Industrial
building: extension, splitting and changing usage.
- office building:
splitting
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No flexibility: the
position of loads is fixed throughout the lifecycle, due to the high
constraints related to the building construction or the high weight of the
supplied process. E.g.: smelting works.
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Flexibility of design:
the number of delivery points, the power of loads or their location are not
precisely known.
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Implementation
flexibility: the loads can be installed after the installation is commissioned.
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Operating flexibility:
the position of loads will fluctuate, according to process re-organization.
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The Installation Flexibility level is based on the following factor:
- Method of Loads distribution in each floor.
Method of Loads distribution in each floor will be one of the following types:
- Localized Loads: localized in certain, fixed and separated positions.
- Intermediate distribution: Localized in certain positions but distributed along the floor.
- Uniform distributed: loads spread out along the floor.
The following table summarizes the effect of Installation Flexibility level and Method of Loads distribution on the Configuration of Electrical Distribution Architecture:
Installation Flexibility Level
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Loads Distribution
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Localized Loads
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Intermediate Distribution
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Uniform Distributed
|
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No Flexibility
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Layout#1
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Layout#1
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Layout#2
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Design Flexibility
|
|||
Implementation
Flexibility
|
Layout#2
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||
Operation Flexibility
| |||
Where:
Layout#1 (see fig.2): The Electrical Distribution Architecture will be that each final load or final panelboards has its directly connected cable to the main low voltage switchgear.
Layout#2 (see fig.2): The Electrical Distribution Architecture will be that many loads or final panelboards will be connected to a busway or bus trunking system directly connected to the main low voltage switchgear.
7- Power Demand
The following table, fig (1) in above and fig (3) summarize the effect of Power Demand on the Configuration of Electrical Distribution Architecture:
Layout#2 (see fig.2): The Electrical Distribution Architecture will be that many loads or final panelboards will be connected to a busway or bus trunking system directly connected to the main low voltage switchgear.
 |
| Fig (2) |
7- Power Demand
#
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Characteristic
|
Definition
|
Choice
|
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7
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Power demand
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The sum of the apparent
load power (in kVA), to which is applied a usage coefficient. This represents
the maximum power which can be consumed at a given time for the installation,
with the possibility of limited overloads that are of short duration.
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< 630 kVA
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630 – 1250 kVA
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1250 - 2500 kVA
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> 2500 kVA
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The following table, fig (1) in above and fig (3) summarize the effect of Power Demand on the Configuration of Electrical Distribution Architecture:
Power
Demand
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|||||
<
630KVA
|
≤
1250KVA
|
≤
2500KVA
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>
2500KVA
|
>
2500KVA (And Several Buildings)
|
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Number
Of Transformers
|
1
|
1
|
> 1
|
> 1
|
> 1
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Number
Of MV/LV Transformer Substation
|
1
|
1
|
1
|
>
1
|
>
1
|
Configuration
Of Electrical
Distribution Architecture (Supply side of Transformers)
|
LV
(No Transformers)
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MV
|
|||
Single-Line / Single Feeder
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Ring-Main
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Duplicate Supply / Open Ring 1 MV Substation
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Duplicate Supply With Double Busbars / Open Ring 2 MV
Substations
|
||
Configuration
Of Electrical
Distribution Architecture (Load side of Transformers)
|
Radial
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Radial
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-
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Ring
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Ring
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Two-Pole Configuration
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Two-Pole Configuration With Two ½ MLVS And No Link
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-
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Interconnected Switchboards
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-
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Double Ended
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| fig (3): Configuration Of Electrical Distribution Architecture (Load side of Transformers) |
In the next topic, I will continue explaining other Electrical installation characteristics. So, please keep following.
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