How many amps are in 400 horsepower with 480 volt three phase?

Answer 1

This might help you. First and foremost is the information the manufacturer puts on the nameplate of the motor. Second, the generic amperage can be found on motor charts that are on the internet. Third you can use a formula to find the approximate amperage. HP = Amps x Volts x 1.73 x %Eff x pf/746. Transposed for Amperage, Amps = HP x 746/Volts x 1.73 x %Eff x pf. Use power factor = .9. Eff = 746 x Output HP/Input watts use 1.5. For estimating a 400 HP motor running on 480 volts. Amps = 400 x 746/ 480 x 1.73 x 1.5 x .9 = 298400/747.36 = 399.27 amps. See how much easier it is to read the nameplate.

Answer 2

In this example, we must realise that the 400 hp represents the rated output power of the machine. To determine the load current, we must first determine the rated input power and, to do this, we need to know the full-load efficiency, which we are not given. So, let's assume that this particular machine has an efficiency of, say, 87%. So we must convert the output power in horsepower to the output power in watts, and divide that figure by 0.87, giving us a rated input power of 443 kW.

The next thing we must understand is that, for a three-phase supply, the quoted value of supply voltage is normally the line voltage (never the phase voltage).

The equation for the power of a balanced three-phase load (motors are always 'balanced' loads) is as follows: power = 1.732 x line voltage x line current x power factor.

Again, we are not given a full-load power factor, so we need to assume a value -in this case, let's assume that it's, say, 0.7.

So we can now determine the line current to the motor:

line current = (rated input power) / (1.732 x line voltage x power factor)

line current = 443 000 / (1.732 x 480 x 0.7) = 760 A(Answer)

Answer 3

Taking the motor at an efficiency of 90% and a power factor of .9 the motor will draw 58 amps.