How do you measure the speed of a motor?

To calculate RPM for an AC induction motor, you multiply the frequency in Hertz (Hz) by 60 — for the number of seconds in a minute — by two for the negative and positive pulses in a cycle. You then divide by the number of poles the motor has: (Hz x 60 x 2) / number of poles = no-load RPM.

Which method is used to measure the speed of an induction motor?

Thus the speed of an induction motor used in electrical drives of an industry is accurately measured using its current signature analysis method.

How is motor current measured?

The motor current of a DC motor can be measured directly in the motor wire. It is required to use a “True RMS” multimeter to measure the motor current due to the chopped PWM motor voltage. A “simple” and commonly in use multimeter with AC or DC selection cannot(!!) measure the motor current properly.

What speed does a motor run at?

Two pole AC motors operating at 60 Hz will always run at approximately 3600 rpm, and four pole AC motors will have speeds around 1800 rpm.

Which instrument is used to measure the speed of motor?

tachometer
A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analogue dial, but digital displays are increasingly common.

How can you measure the speed of a motor without a tachometer?

You could use a stroboscope. The speed will depend on the slip. The slip will be dependant on the load. At no load the slip will be negliable, in fact right until the motor approaches overload the speed will be very close to the frequency of the supply.

How do you calculate the number of poles of a motor?

The formula is n = 60 x f /p where n = synchronous speed; f = supply frequency & p = pairs of poles per phase. The actual running speed is the synchronous speed minus the slip speed.