full load current of a 3phase 1.5Kw motor

[lyncher366]

can anyone please help me with this. how to calculate th full load current of a 3phase 1.5Kw motor, i need to know this to set the overload relay to the value, thanks

 

[Marvo]

It varies depending on efficiency etc. What does it say on the info plate on the motor?

Your best bet is to run the motor under normal load conditions and check the current with a clamp meter. Set the thermal overload at that current plus 10% (ASSUMING IT'S LESS THAN THE MAX CURRENT STATED ON THE INFO PLATE).

 

[stewac8]

Full load amps is 3.6

 

[Knobhead]

=(((((KW/3)/(V/Sqrt(3)))*1000)*((1-PF)+1))/(Eff*100))

 

[vaughant]

Homework time again!!!!
you need to know the voltage as three phase comes in all different levels of voltage,240/415/440/500/690 etc.

 

[rattlehead85]

As mentioned you first need to check the data of the motor usually found on the plate.
This should include Voltage, Input Power, PF (cos)
You can work out the input power by using the formula
Input (W) = Output(W) / Efficiency (%)

Then.

Line Current (A) = Input(W) / {sqr3 x Voltage(400v) x PF(cos)}

Hope this helps.