what IS the formula for calculating the input current of a machine if you have k.w.power factor and voltage?

Answer 1

Youneed to define a couple of things better to get your question answered correctly. One of these is whether the system is connected in a WYE or DELTA configuration, and the other is whether it is a SINGLE or MULTIPLE phase connection.

Assuming you have a three-phase, wye connection:
(Line Current in amperes) * (Line Voltage in volts) = (Power in Volt-amperes)
(Power in watts) = (Power in volt-amperes) * (power factor)

Therefore,
(Amps) = (Watts) / (power factor) / (volts)

Answer 2

I=kW*1000/(V*pf)

or to put another way calculate VA = (kW*1000)/pf

then divide by V.

eg 1kw machine with 0.75 pf

=1333.3 VA

divide by 230V

=5.8A

if three phase 400V line then exactly the same as above but divide by 3 at the end ie 1.76A

Answer 3

P = I x E x PF (x Sq Root of 3 (if 3phase))
P = KW (Power)
I = Current
E = Voltage
PF = Power Factor
Sq Root of 3 = Factor to allow for 3 phase power (Leave out if single phase)

I = P / E x PF x Sq Root of 3

Answer 4

V*I=VA*pf =W so W/V=I... A 3kVA load with a pf of 0.9 supplied by 240v 50Hz = 3000*0.9=2.7kW therefore the current is 2700/240=11A. Note if the known rating is in kW you don't need the pf.

Answer 5

Amps X Volts = Watts or
Amps = watts/volts

Answer 6

Power (kW) = Voltage (V) x Amps (I), so
Amps (I) = Power (kW) / Voltage (V)