Electric Motor Torque Calculation Formula & Torque Calculator Online

Motor Torque Calculator:

Enter the input voltage in volts, current in amps, speed in RPM and power factor. Choose the motor types. For DC motor, pf is one.

Select Motor type:  
Enter Current in Voltage: V
Enter current in Amps: A
Enter Speed in RPM: RPM
Reset – Torque in Nm: Nm

How to calculate torque of motor:

Torque is nothing but a momentary force developed at the time of force is applied to the motor. The unit of torque is N.m (Newton-meter). In other words, Torque T(N.m) is equal to the ratio between the electrical power P(W) in watts to the acceleration.

The total power rating of the motor details can be found from the motor’s nameplate details. Absence of the power details, the power is equal to the product of the voltage and current for DC motor and for AC motor, the product of the voltage, current and power factor.

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The speed of the motor can be found by using Speed measurement devices.

Hence motor torque T = P / ω

Here omega ω is equal to 2 x pi x N(rpm) / 60

For DC Motor torque Formula:

For Calculating, Torque for DC motor

T = V x I / (2 x pi x N(rpm) / 60)

N(rpm) is the speed of the motor

V => Input DC Voltage

I => Input DC Current

For Single phase AC motor torque formula:

T = V x I x pf / (2 x pi x N(rpm) / 60)

V => Input AC Voltage in volts (line to neutral voltage)

I => Input AC Current in amps

For three phase AC motor torque formula:

T = 1.732 x V x I x pf / (2 x pi x N(rpm) / 60)

V => Input AC Voltage in volts (line to line voltage)

I => Input AC Current in amps

Also while reducing the motor power the torque will be reduced.

i.e if you are running  y% of load, then the torque would be,

T = 1.732 x V x I x pf x y% / (2 x pi x N(rpm) / 60)

here V => rated voltage

I => rated current

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AC 1 HP single-phase AC motor has an input voltage of 230V, the input current of 3.8 Amps and working at 2500 rpm, 0.8 pf, 100% load. Calculate the torque of the motor.

Apply our formula 1,

T(N.m) = 230 x 3.8 x 0.8 x 100% / (2 x 3.14 x 2500 / 60) = 2.66 N.m

The torque produced by the motor is 2.66 Nm.

Hence 1 HP motor can produce 2.66 N.m


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