Calculate Design Current of Electrical Load

 

Design Current :

kVA and KW :

kVA = KW / PF; Let's say the power factor is 0.8, which means KW is 80% of kVA

For a 10 KW Load, kVA would be 12.5 kVA

"Consequently, we can calculate the Current as well. "

The four load types broadly are R-TPN, R-SPN, M-TPN, and M-SPN. If the load type is Resistive or Motor.

The formula used for each load type calculation is as follows:

• R-TPN: ((MaxKw * 1000 * 1.2) / (1.73 * 415 * 0.8))
• R-SPN: ((MaxKw * 1000 * 1.2) / (240 * 0.8))
• M-TPN: (MaxKw * 2.61)
• M-SPN: (MaxKw * 8#)

• For Resistive 3-Phase Load = MaxKw * 2.08 (Voltage 415V, PF 0.8)
• For Resistive 1-Phase Load = MaxKw * 6.25 (Voltage 240V, PF 0.8)
• For Motor 3-Phase Load = MaxKw * 2.61 (Voltage 415V, PF 0.8)
• For Motor 1-Phase Load = MaxKw * 8 (Voltage 240V, PF 0.8)

Example: Design Current for the R-TPN Load of Max 10 KW value is 20.89 A

But the Calculated current can be less i.e (MaxKW * 1.74) = 17.40 A

"1.74 comes from this 1000/(1.73 * 415 * 0.8) "

It means Design Current is 20% (1.2 times) more than the calculated current in this case.