Electric motor specs

[made2hack]

Hi all,

I picked up a 230V/50Hz motor recently whose specifications plate is all scratched off. How do I determine the nominal power ?

Here's what I mean:

It pulls a bit over 4 Amps no load. On startup, it might go up as high as 11 Amps, and then stabilizes at around 4A.

Is it a 1Kw motor? Is the power of the motor calculated with no Load? Or under load?

The shaft also spins at around 2900 - 3000 Hz, I assume it is 2 pole?

Thanks,

[Zero999]

Post a picture.

How heavy is it?

Have you looked inside it?

Are you sure it's an induction motor and not a universal motor?

[Vtile]

3-phase or 1-phase?

[Benta]

230 V, 50 Hz would be 1-phase.

[Vtile]

230 V, 50 Hz would be 1-phase.

It can mean anything. Better to ask and not spill 3 pages of instructions and then find out that it meant that the motor were driven in a country with 230/50 system.

[Benta]

True, especially as the OP is very secretive about his location...

[made2hack]

Hi,
Sorry for the late reply, it is a 1 Phase (by the looks of it) 230V AC.
I posted a picture.
It weighs maybe 8 kg?

[made2hack]

Maybe it was 3 phase, but adapted via caps for 1 phase?
I mean, the caps don't have a place to connect them, they just kinda float.

[EPTech]

Yes,

Looks like a 1 phase induction motor with running capacitors, maybe 750W.

The running capacitor looks a bit bulky for such a small motor IMO. That is why the current may be higher. The previous owner may have done this in an attempt to increase the starting torque, but you may end up burning the auxiliary winding. What are the values on the capacitors? If the motor starts up and keeps running with a smaller running capacitor in your application, leave it at that.

Happy, commutating.

[made2hack]

Hi

The running capacitor looks a bit bulky for such a small motor IMO. That is why the current may be higher. The previous owner may have done this in an attempt to increase the starting torque, but you may end up burning the auxiliary winding. What are the values on the capacitors? If the motor starts up and keeps running with a smaller running capacitor in your application, leave it at that.

They are 4 x 4.7uF 380V in parallel, so I guess just under 20uF total. The previous owner stated they used the caps to start the engine under load. I might omit them entirely as the motor will be used for a disc sander which shouldn't be started under load.

Thanks,

[Zero999]

Hi

The running capacitor looks a bit bulky for such a small motor IMO. That is why the current may be higher. The previous owner may have done this in an attempt to increase the starting torque, but you may end up burning the auxiliary winding. What are the values on the capacitors? If the motor starts up and keeps running with a smaller running capacitor in your application, leave it at that.

They are 4 x 4.7uF 380V in parallel, so I guess just under 20uF total. The previous owner stated they used the caps to start the engine under load. I might omit them entirely as the motor will be used for a disc sander which shouldn't be started under load.

Thanks,

The capacitors are required for the motor to start reliably. Without them, it might hum or start in an unpredictable direction, if you're lucky. You might be able to get away with less capacitance, in an application requiring less starting torque, but some is still needed.

[EPTech]

Hero999 is right.

You should not get rid of them. If they are only used for starting, there may be a centrifugal switch somewhere. If so, that switch should detach the start capacitors at about 2/3 of the synchronous speed (about 3000 rpm for a 2-pole motor), so 2000 rpm.
But looking at your terminal box, I think the capacitors are permanently attached.

Happy sanding.

[SeanB]

Needed to start and run the motor, and inside the terminal cover there is a wiring diagram, which might still have a legible value for that capacitor. Typical value for these on that size motor is from 8-12uF 400VAC rating.