Benefits Of Having Power Factor Meter For Induction Motors

<yawn> What size of motor?

<yawn> How close to its maximum output is it?

The indication will be anywhere between 0 and 1.

Hi chuahtc,

you know that induction motors are inductive loads, which means they have a lagging power factor.. However,as far as I know that when such a motor is about to breakdown( for example because of their bearings), it'll draw current higher than its rated current, this incremental current on long time is causing an insulation deterioration of that motor in question,,,,, on the other hand, have in mind that in the inductive loads(E.g induction motors), the load's drawn current will be affected the value of the power factor, by other words, when the drawn current (of a motor) is higher, then the power factor will be smaller (P.F<<1 ) and vice versa ...........

Hope this helps.

People sometimes use PF measurement as a way to determine motor loading, i.e. as the motor load decreases, the power factor drops (moves closer to 0). This is often considered more reliable than looking at current alone because current is more directly affected by applied voltage. The better load monitors look at PF and compare that to load current to calculate what is called "Active Current", which gives a more linear relationship to loading.

I have never heard of using PF measurement as a way to determine insulation health, but I suppose that if you trended it over time you could theoretically see that if total current in relation to PF was increasing, then the probable cause might be an increase in losses due to insulation breakdown.

I believe what you are referring to is "Insulation Power Factor Testing" (also known as dissipation factor or tan-delta testing). It is a measure of insulation quality performed using an applied AC voltage (rather than the usual DC used for megger / hipot testing). It treats the apparatus as a capacitor (two conductors with insilation / dielectric between) and calculates a % power factor that is a measure of how good a capacitor the insulation is (= how well it insulates). It is an off-line test,and one of the best known makers of the equipment is Doble Engineering.

This is usually done on HV equipment: Motors & generators 5kV and up, power transformers, HV circuit breakers, etc.

Anyway a power factor meter, which measures the power factor of the electrical supply to the motor, will not give you this information.