how to choose circuit breakers with ratings of power?
HOW TO SIZE GENERAL
BREAKER Monopolar Bipolar Tripolar
Basic formulas Find single-phase current Power (W or kVA) Current (A) = Electric voltage (V) Find two-phase current Power (W or kVA) Current (A) = Phase-phase voltage (V) Find three-phase current Power (W or kVA ) Current (A) = 13 x Phase-to-phase voltage (V) 13 = 1.73
A residence has an installed load of 4.5kW. What should the nominal current of the general circuit breaker be? Consider single-phase power. Voltage between phase and neutral 127V.
A residence has a maximum demand of 22kVA. What should the nominal current of the general circuit breaker be? Consider three-phase power. Voltage between phase and phase 220V.
Step 1 Multiply the maximum demand in EVA by 1000 to convert to VA. 22 x 1000 = 22000VA 2 ° Step Divide the VA power by multiplying the root of three by phase-V voltage to find the electrical current in A. 22000 / (1.73 x 220) = 57.74A (per pole ) Step 3 Opt for a nominal current circuit breaker slightly higher than the calculated current. IN = 63A (Nearest commercial value above)
A residence has an installed load of 13.3kW. What should the nominal current of the general circuit breaker be? Consider biphasic feeding. Voltage between phase and phase 220V.
1st Step Multiply the power in kW by 1000 to convert to W. 13.3 x 1000 = 13300W 2 ° Step Divide the power in W by the phase - phase voltage in V to know the electric current in A. 13300/220 = 60 , 45A (per pole) 3 ° Step Opt for a nominal current circuit breaker slightly higher than the calculated current. IN = 63A (Nearest commercial value above)
