Generally for electric motor size,it rated by horsepower (hp) or kilowatts (kW) unit.We can recognize the electric motor size when refer to their kilowatts or horsepower.So from power (kW/hp), how we can know the full load ampere for electric motor?

This time i want share about how to calculated the full load ampere (FLA) of electric motor from their power rated.It not difficult if we know the right formula to get the answer.From this calculation we only can estimate the value of full load ampere.

We cannot get the actual full load ampere because it depend on efficiency of motor.If electric motors have a higher efficiency rating,it will draw fewer amps, for example a 10 HP motor with a 60% efficiency rating will draw about 65 amps at 230 VAC compared to about 45 amps for a motor with a 80% rating.

**How to calculate from power ( kW & HP ) to ampere ( I )?**

**1) Kilo watt (kW) to ampere ( I )**

For 3 phase power supply ; **kW = I x V x 1.732 x pf**

For 1 phase power supply ; **kW = I x V x pf**

Example : 1 unit compressor size rated 37 kw,415 VAC,3 phase and 80% pf,calculate the full load ampere?

Calculation :

kW = I x V x 1.732 x pf

I = kW / (V x 1.732 x pf )

I = 37 / (415 x 1.732 x 0.8 )

I = (37 / 575) x 1000

*I = 64.4 ampere ( full load ampere)*

**2) Horse power ( hp ) to ampere ( I )**

First we must convert from hp to kW using this formula :

1 Hp = 0.746 kW

After that use the formula kW to ampere :

For 3 phase power supply ; **kW = I x V x 1.732 x pf**

For 1 phase power supply ; **kW = I x V x pf**

Example :-

1 unit induction motor power rated 25 hp,200 VAC,3 phase,90 % power factor,calculated the full load ampere.

Calculation :-

kW = 25 hp x 0.746

kW = 18.65

kW = I x V x 1.732 x pf

I = kW / V x 1.732 x pf

I = 18.65 / ( 200 x 1.732 x 0.9 )

I = (18.65 / 311.76) x 1000

I = 59.8 ampere ( full load ampere )

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Should we take into consideration the efficiency of the motor?.

For efficiency is not compulsory if we don’t have the value.,we can ignore the value :D

In your formula Efficiency factor is not accounted – is there some reason for this. I thought the formula was kW = I x V x 1.732 x pf x Efficiency?

Yes Steve..it true.You can include with efficiency value if you know but if not you can skip it.

What is 1..732

Square root 3 = 1.732

√3 = 1.732

Hi. May I help you to calculate the electrical load list of power plan.

amir.masror@gmail.com

Hi! Is the power factor required also? or If I didn’t know the p.f. can I use 0.8? Our motor specs are 18.5KW, 460V, 3PH.

Hi,Normally i just put PF to 1 but it’s ok to put PF 0.8

hiii

you can also use

KW = √3 × V× I × cos¢

cos¢ = 0.8

Yes Akash,Thanks for sharing the formula

how could we calculate if we don’t know pf…?

KW/KVA

a motors rating 10kw !!!!! what its means this motor will consume 10 kw per sec ??? or 10 kw per hr?????

how did you come about the 1000?please assist

how can i found 3 ph motor efficiency

You should say P = √3VIcos¢

Watt is the unit of power, to convert Watt to kilo watt divide by 1000

Then no confusion about 1000

a 48v dc motor with nominal power 11kw. how can i calculate pf

WHAT IS THE FORMULA AS UNDER:

440 V, 60 H.P., 55 AMPS, PF .95 & 12 HOURS

NOW WE WANT HOW MUCH UNITS WILL CONSUMPTION AS ABOVE POINTS.

1 HP = .746 KW

GIVEN DATA IS 20 HP AND WE NEED TO FIND THE AMPS RATING

20 HP = 20 * 0.746

= 14.92 KW

HERE 14.92 KW , IT IS 3-PHASE ( ABOVE 4 KW WE CONSIDER 3-PHASE AS PER NEC )

P = √3 V I cos¢

P = 14.92 KW

V = 415 V

cos¢ = 0.8

√3 = 1.732

I = ????

P = √3 V I cos¢

I = ( P / √3 V cos¢ )

I = (( 14.92*1000 ) / ( 1.732 * 415 * 0.8 ))

I = 25.94 A

I = 26 A

yes

I made a blower. The fan is OD 33.5″

6″thickness and 55 kg Wight

Which power motor required (HP)

I made a blower. The fan is OD 33.5″

6″thickness and 55 kg Wight

Which power motor required (HP)

2800 rpm

hiee, for 3 phase 1kw ac motor how much the maximum current rating is acceptable?

How to calculate amper when horsepower is given for 3 phase ?

A 20 H.P, 3 Phase supply ,50Hz , 440 Volt in induction motor .find out full load current?

we are having 3-phase BLDC hub motor (800W ,48V).

we have to run this motor for 2 hours with Lithium-ion battery.

Then how to decide the battery capacity?

how to find pf