Heat Loss from Electrical Equipment
Heat loss from electrical equipment like switch gear, transformers and variable frequency drives
Heat loss to the ambient air from some typical electrical equipment are indicated below:
Transformers
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
- 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
- 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 : 2 - 6% of kVA rating
- Bus duct : 0.015 Watts /ft Amp
- Capacitors : 2 Watts / KVAR
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