starting capacitor size

[tanii51]

i have a 3/4 hp royco bench grinder thats always had intermittent start up problems . i can hear the switch gear switching off when it stops but when it starts it some times needs some help. i just checked the start capacitor 125vac/150 uf is this the right value i thought the vac should be much higher for 240 v

[lnt9000]

i have a 3/4 hp royco bench grinder thats always had intermittent start up problems . i can hear the switch gear switching off when it stops but when it starts it some times needs some help. i just checked the start capacitor 125vac/150 uf is this the right value i thought the vac should be much higher for 240 v

Assuming a single phase induction motor, These are generally rated at 400VAC , note it is important to choose the correct value for the motor otherwise the starting torque of the motor will change, Is it a usa Import?

[tanii51]

thanks int9000 for reply the bench grinder is a royco / 8 inch model hc8/made in australia stamped on the label also amps 3.5 its about 15 years old i bought it from a farm auction and as i said its always had this intermittent starting problem . i just wonder if maybe the capacitor has been changed before i purchased it \

[bennylaird]

The rating of 125VAC is just a parameter, ie designed to do the job at that rating. It may work well at 240VAC without destroying itself but should be replaced with a higher saftey rating of 400VAC.

It's the value of capacitance that is related to its performance. I would tend to think that it has changed capacitance due to either being out of tolerance or damaged due to exceeding the rating.

I would replace it with a 400VAC 150uf or similar.

[tanii51]

thanks benny i think that may fix the problem