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Heat Loss from Electrical Equipment

Heat loss from electrical equipment like switch-gear, transformers and variable frequency drives.

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Heat loss to the ambient air from some typical electrical equipment are indicated below:

Transformers

Electric transformer

Transformers are in general highly efficient and large power transformers - 100 MVA and larger - can be more than 99% efficient. Smaller transformers - like used in consumer electronics - may be less than 85% efficient.

Heat loss for

150 kVA and smaller : 50 Watts/kVA (aprox. 5%)
150 - 500 kVA : 30 Watts/kVA (aprox. 3%)
500 - 1000 kVA : 25 Watts/kVA (aprox. 2.5%)
1000 - 2500 kVA : 20 Watts/kVA (aprox. 2%)
larger than 2500 kVA : 15 Watts/kVA (aprox. 1.5%)

Switch Gear - Circuit Switch Breakers

Circuit switch breaker

Low voltage breaker 0-40 Amps : 10 Watts
Low voltage breaker 50-100 Amps : 20 Watts
Low voltage breaker 225 Amps : 60 Watts
Low voltage breaker 400 Amps : 100 Watts
Low voltage breaker 600 Amps : 130 Watts
Low voltage breaker 800 Amps : 170 Watts
Low voltage breaker 1600 Amps : 460 Watts
Low voltage breaker 2000 Amps : 600 Watts
Low voltage breaker 3000 Amps : 1100 Watts
Low voltage breaker 4000 Amps : 1500 Watts
Medium voltage breaker/switch 600 Amps : 1000 Watts
Medium voltage breaker/switch 1200 Amps : 1500 Watts
Medium voltage breaker/switch 2000 Amps : 2000 Watts
Medium voltage breaker/switch 2500 Amps : 2500 Watts

Motor Control Centers

Electric motor starter

Section : 500 Watts per section
Low voltage starters size 00 : 50 Watts
Low voltage starters size 0 : 50 Watts
Low voltage starters size 1 : 50 Watts
Low voltage starters size 2 : 100 Watts
Low voltage starters size 3 : 130 Watts
Low voltage starters size 4 : 200 Watts
Low voltage starters size 5 : 300 Watts
Low voltage starters size 6 : 650 Watts
Medium voltage starters size 200 Amp : 400 Watts
Medium voltage starters size 400 Amp : 1300 Watts
Medium voltage starters size 700 Amp : 1700 Watts

Variable Frequency Drive

Variable frequency drive

Variable frequency drive : 2 - 6% of kVA rating
Bus duct : 0.015 Watts /ft Amp
Capacitors : 2 Watts / KVAR

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Related Topics

Air Conditioning - Air Conditioning systems - heating, cooling and dehumidification of indoor air for thermal comfort

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