In the previous Topic; Power system architectures for the commercial buildings – Part One , I explained the first type of Power system architectures for the commercial buildings which was “Low building, type 1: One supply section” and today I will explain the second type; Low building, type 2: Two supply sections as follows.
You can also review previous topics about electrical design requirements for commercial buildings for good following-up:
2- Low building, type 2: Two supply sections
Conditions for using this power system architecture:
1- If the following rule is verified:
The number of building floors must not exceed the max. Number of floors for Two supply sections (i) calculated by equation#1.
If:
Max. Side length of the building = a (in meter)
One Floor area A = a2 (in square meter)
Height per floor = h (in meter)
Then:
Max. Number of floors for Two supply sections (i) ≤ (100 – 2a) / h (equation#1)
If the number of floors exceed the max. Number of floors for one supply section (i) calculated by equation#1, then we must use other types of power system architecture.
Note: all buildings have number of floors ≤ 4 are low rise buildings.
2- If the floor area of the building > 2,000 m2.
Note: if floor area > 2,000 m2, so there will be more than one (≥ 2) central equipment room per floor feed from the LVMD (Low Voltage Main Distribution switchgear).
3- If the power density of the building loads have the following limits:
- Power required >2,000 kW.
- Segmentation of power required 85 % utilized area (i.e. functional area like Offices, Briefing rooms, Data center, Canteen kitchen with casino, Heating/ventilation/air conditioning, Fire protection and Transport) And 15 % side area (i.e. shafts, fountains, green area, sky lighting area and etc.).
4- If the power supply needed for the building have the following requirements:
- Supply types 100 % total power from the public grid; (Supply of all installations and consumer Devices available in the building).
- 10–30 % of the total power for safety power supply (SPS) from generators; (Supply of life-protecting facilities in case of danger, e.g.: Safety lighting, Elevators for firefighters, Fire-extinguishing equipment).
- 5–20 % of the total power for uninterruptible power supply (UPS); (Supply of sensitive consumer devices which must be operated without interruption in the event of a NPS failure / fault, e.g.: Tunnel lighting, airfield lighting, and Servers / computers and Communications equipment).
Example for " Low building, type 2: Two supply sections " power system architecture:
We have a building with 2,400 KVA total load power, 4 floors and floor area 2,500 m2 with total area 10,000 m2.
Solution selected for this building is using the Two supply section power system architecture as follows:
For this example the power system architecture will be as follows:
Solution selected for this building is using the Two supply section power system architecture as follows:
|
Design
solution
|
Advantages
of this solution
|
Benefits
from this solution
|
|
Using Two supply sections per
floor
|
Supply at the load center, short
LV cables, low losses
|
Low costs, time savings during
installation
|
|
Radial network
|
Transparent structure
|
Easy operation and fault
localization
|
|
Transformer module with 2 ×
1200 kVA,
|
Minimization of voltage
fluctuations, lower statics requirements on
building structures
|
Optimized voltage quality, Cost minimization in the
building construction work
|
|
Redundant supply unit:
– Generator 730 kVA (30 %)
(the smaller the generator, the greater the short-circuit current must be compared to the nominal
current)
– UPS 400 kVA (15 %)
|
Supply of important consumers
on all floors in the event of a fault, e.g. during power failure of the
public grid
|
Increased reliability of
supply
|
|
Safety power supply
|
Safety power supply in acc.
With DIN VDE 0100-718
|
|
|
Supply of sensitive and
important consumers
|
Uninterruptible supply of
consumers, e.g. during power
failure of the public grid
|
|
|
Use Medium-voltage switchgear
from type SF6 gas-insulated
|
Compact switchgear;
independent of climate
|
Minimized space requirements
for
electric utilities room; no
maintenance required
|
|
Use Transformer from type
cast-resin with reduced losses
|
Low fire load, indoor
installation
|
Economical
|
|
Use Low-voltage main
distribution with central grounding
point ( which splitting of PEN in PE
and N to the TN-S system)
|
EMC-friendly power system
|
Protection from
electromagnetic
interference (e.g. to prevent
lower transmission rates at
communication lines)
|
|
Use Wiring / main route as
cables
|
Central measurement of
current, voltage, power, e.g. for billing, cost center allocation
|
Cost transparency
|
|
Use Connection inside
substation ( Transformer – LVMD- NPS – SPS) as busbars
|
Easy installation
|
|
For this example the power system architecture will be as follows:
 |
| " Low building, type 2: Two supply sections " power system architecture |
Where:
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NPS
|
Normal
power supply
|
|
PCO
|
Power
company or system operator
|
|
FF
|
Firefighters
|
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HVAC
|
Heating
– Ventilation – Air conditioning
|
|
MS
|
Medium-voltage
switchboard
|
|
LVMD
|
Low-voltage
main distribution
|
|
SPS
|
Safety
power supply
|
|
UPS
|
Uninterruptible
power supply
|
|
z
|
Power
monitoring system
|
In the next Topic, I will explain the “High-rise building, type 1: Central power supply, cables” power system architecture. So, please keep following.
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