how can we measure the efficiency of a dc motor?

Question

what meters or devices we need to measure the effeciency of a dc motor? how should we use these meters or devices?what is the simplest way to measure the efficiency of a dc motor?

Answer 1

A voltmeter and an ammeter will provide the input power. You will need some form of dynamometer to measure output power.

Output power divided by input power yields efficiency.

Answer 2

A DC motor like most other motors convert electrical energy into mechanical energy. In other words, the efficiency of a motor should be measured in amount of mechanical energy generated for a given amount of electrical energy.

I suppose the output mechanical energy/power can be measured in terms of horsepower or torque produced by the motor or the speed at which the motor's shaft is moving or other suitable parameters. The input energy obviously will be the electrical energy(power).

Unfortunately, I am not sure how you would measure a motor's output horsepower. The RPM of the motor's shaft or the torque can be measured by suitable electronic devices such as a torque meter etc.

Hope this helps.

Answer 3

Maybe try a high power shunt resistor connected to the output of a second motor of the same design, with the motor shafts connected. Measure the voltage across the (known) resistance to determine the current through the load, then multiply the current by the voltage to determine power in watts. Since you already have the input power using the method suggested by the others just complete the formula. I would try a number of input voltages and currents. I think your answer would have to be multiplied by two, since there would be losses from both motors.

Answer 4

I read somewhere that you can also roughly measure efficiency by measuring how much heat the motor gives off. After all, input power - output power = heat.

Answer 5

Efficiency is always Output Power / input Power


u can measure power input by using a simple voltmeter & ammeter
& power =V * I

for output power u need to figure out something...