Demand factor (in IEC, Max.Utilization factor (Ku)):
- The word “demand” itself says that means of Demand issue. The magnitude relation of the utmost coincident demand of a system, or a part of a system, to the full connected load of the system.
- Demand Factor = Maximum demand / Total connected load
- For example, an oversized motor 20 kW drives a constant 15 kW load whenever it is ON. The motor demand factor is then 15/20 =0.75= 75 %.
- Demand Factor is expressed as a percentage (%) or in a ratio (less than 1).
- Demand factor is always < =1.
- The lower the demand factor, the less the system capacity required to serve the connected load.
Calculation:
- A Residence shopper has ten No’s Lamp of four hundred W however at the identical time, it’s doable that solely nine No’s of Bulbs are used at an identical time. Here Total Connected load is 10×40=400 W. shopper most demand is 9×40=360 W. Demand Facto of this Load = 360/400 =0.9 or 90%.
- One shopper has ten lights at sixty power unit every in room, the load is sixty power unit x ten = 600 power unit. this can be true as long as All lights are activated identical time (Demand factor=100% or 1)
- For this shopper, it’s ascertained that solely half the lights being turned ON at a time thus we will say that the demand issue is zero.5 (50%). The calculable load = 600 power unit X zero.5 = 300 kW.
Use of demand factors:
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Feeder conductors ought to have sufficient Ampere capability to hold the load. The Ampere capability doesn’t invariably be up to the overall of all masses on connected branch-circuits.
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This issue should be applied to every individual load, with specific attention to electrical motors, that square measure terribly seldom operated at full load.
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As per the National Electrical Code, (NEC), the demand issue is also applied to the overall load. The demand issue permits a feeder ampacity to be but one hundred pc of all the branch-circuit masses connected thereto.
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Demand issue is often applied to calculate the scale of the sub-main that is feeding a Subpanel or a set load sort of a motor etc. If the panel incorporates a total load of 250 kVA, considering a requirement issue of zero.8, we will size the feeder cable for 250 x zero.8= 200 kVA.
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Demand factors for buildings usually vary between fifty and eighty you look after the connected load.
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In Associate in Nursing industrial installation, this issue is also calculable on a mean at zero.75 for motors.
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For incandescent-lighting masses, the issue invariably equals one.
Demand Factor |
|
Text Book of Principal of Power System-V.K.Mehta |
|
Utility |
Demand Factor |
Residence Load (<0.25 KW) |
1 |
Residence Load (<0.5 KW) |
0.6 |
Residence Load (>0.1 KW) |
0.5 |
Restaurant |
0.7 |
Theatre |
0.6 |
Hotel |
0.5 |
School |
0.55 |
Small Industry |
0.6 |
Store |
0.7 |
Motor Load (up to 10HP) |
0.75 |
Motor Load (10HP to 20HP) |
0.65 |
Motor Load (20HP to 100HP) |
0.55 |
Motor Load (Above 100HP) |
0.50 |
Demand Factor For Industrial Load |
|
Text Book of Design of Elect. Installation- Jain |
|
Electrical Load |
Demand Factor |
1 No of Motor |
1 |
Up to 10 No’s of Motor |
0.75 |
Up to 20 No’s of Motor |
0.65 |
Up to 30 No’s of Motor |
0.6 |
Up to 40 No’s of Motor |
0.5 |
Up to 50 No’s of Motor |
0.4 |
Demand Factor |
|
Saudi Electricity Company Distribution Standard |
|
Utility |
Demand Factor |
Residential |
0.6 |
Commercial |
0.7 |
Flats |
0.7 |
Hotel |
0.75 |
Mall |
0.7 |
Restaurant |
0.7 |
Office |
0.7 |
School |
0.8 |
Common Area in building |
0.8 |
Public Facility |
0.75 |
Street Light |
0.9 |
Indoor Parking |
0.8 |
Outdoor Parking |
0.9 |
Park / Garden |
0.8 |
Hospital |
0.8 |
Workshops |
0.6 |
Ware House |
0.7 |
Farms |
0.9 |
Fuel Station |
0.7 |
Factories |
0.9 |
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