Breaker Size for 216kW, 400V, 3 phase, 50 Hz Electric Heater

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Shahzad

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Electrical Engineer
Hey everyone,

I am wondering what should be the appropriate breaker frame and trip setting for 216kW, 3 phase, 400V, 50 Hz Heater. I believe the FLA would 326A, since it is electric heater, so power factor is 1.0. Bases on this, if I understand correctly, I could go maximum of 250% to select inverse time breaker trip setting, so to be realistic, if I consider 125% factor instead of 250%, I get 407A, so does this means I can get a thermal mag breaker of 410A for my 216kW load? Any thoughts?
 
Not familiar with the Canadian Code. Is 410 a standard size breaker ??
If my math is correct,. you could use a 400 amp breaker.
 
augie47 said:
Not familiar with the Canadian Code. Is 410 a standard size breaker ??
If my math is correct,. you could use a 400 amp breaker.
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So shall I select 600 A frame with 400Amp trip setting breaker? This seems to be only option I guess. or can I get a 450A, thermal mag, 65kA, 400V, 50 hz breaker?
 
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216kW / 400V / 1.732 = 312A, x 1.25 would be CONDUCTORS rated for 390A, and the breaker must be sized to protect the conductors. The "250%" rule applies to MOTOR loads. This is not a motor load. 400A breaker.
 
Jraef said:
216kW / 400V / 1.732 = 312A, x 1.25 would be CONDUCTORS rated for 390A, and the breaker must be sized to protect the conductors. The "250%" rule applies to MOTOR loads. This is not a motor load. 400A breaker.
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I don't know what the IEC rule about such things is.
 
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