# Frequent question: How do you calculate the input current of a DC shunt motor?

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## How do you calculate the input power of a DC motor?

Given the voltage, armature resistance and Ohm’s law, you are able to find the current and therefore get the input power. Then divide your input power by your angular velocity to obtain your torque at that speed. The input power is volts multiplied by amps.

## How do you determine the load current of a DC shunt motor at which the motor efficiency is maximum?

Equation (1) shows that the efficiency of a DC generator is maximum when those losses proportional to the square of the load current are equal to the constant losses of the DC generator. This relation applies equally well to all rotating machines, regardless of the type of machine.

## How do you calculate motor input power?

By taking the voltage and multiplying it by the associated current, the power can be determined. A watt (W) is a unit of power defined as one Joule per second. For a DC source the calculation is simply the voltage times the current: W = V x A.

## What is the formula for power output?

Power = force multiplied by speed (velocity) P = F × v.

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## How do you calculate current input?

Input and output power

1. Electrical power is calculated by multiplying voltage (in volts) by current (in amps).
2. If a transformer is 100% efficient, then the input power will equal the output power. …
3. V P is input (primary) voltage.
4. I p is input (primary) current.
5. V s is output (secondary) voltage.

## What are the characteristics of DC shunt motor?

Characteristics of a DC Shunt Motor:

• Speed-Armature Current Characteristic: …
• Torque-Armature Current Characteristic: …
• Speed-Torque Characteristic: …
• Break in Field Circuit of a DC Motor:

## What is the formula for efficiency?

Efficiency is often measured as the ratio of useful output to total input, which can be expressed with the mathematical formula r=P/C, where P is the amount of useful output (“product”) produced per the amount C (“cost”) of resources consumed.

## How does power factor affect Motors?

Power factor and motor efficiency

The real power (kW) produces work and heat. The reactive power (kVAR) establishes the magnetic field in the motor that enables it to operate. The PF of a motor is lower when the motor is under-loaded and is significantly reduced when the motor load is less than 70%.