Record Power Planer Thicknesser - RSPT260 - Connect Motor to Mains

[JohnerH]

Hi,

I have the above Jointer, I need to test the motor as part of troubleshooting,

It has this motor,

Would anything catastrophic happen if I plugged it in directly to the house single phase mains?

I think the mains runs @ 13amps?

Thanking you...

 

[guineafowl21]

The inrush current, perhaps 40A, would likely pop the breaker, or blow the plug fuse. Nothing catastrophic, it just might not work.

 

[Sachakins]

If you disconnect the drive belt frst, it's unlikely to blow a fuse.

 

[thikone]

You might need to change MCB to type C to run this motor.

Normally, in house type B is used which is more sensitive for short duration surge of current.
Induction motors usually require type C.
From what I have tested 375W and 750W inductor motors works just fine with type B 13A.

Just test it (but be ready for MCB trip) and if it doesn't work change to type C of the same amperage.
Type C allows for 10x times more than nominal current for a short time while type B allows only 5x time.
Something like C13 A MCB should be fine for any house or even C16 A.

 

[Sachakins]

@JohnerH
Please update us as to what happens when you do connect, will be interesting to know

 

[JohnerH]

Thank you,

It'll probably sometime in the weekend. I'll keep everyone posted.

 

[Spectric]

and if it doesn't work change to type C of the same amperage.

A dangerous practice unless you can confirm that the loop impedances are satisfactory to allow sufficient fault current to flow in order to cause a type C to disconnect, they require upto 10x the fault current of a type B !

That motor will work ok if connected via a 13 amp plug with no load connected but you don't mention if it is on the bench or fixed in the machine so if it is on the bench ensure it is clamped down before applying power.

 

[thikone]

A dangerous practice unless you can confirm that the loop impedances are satisfactory to allow sufficient fault current to flow in order to cause a type C to disconnect, they require upto 10x the fault current of a type B !

That motor will work ok if connected via a 13 amp plug with no load connected but you don't mention if it is on the bench or fixed in the machine so if it is on the bench ensure it is clamped down before applying power.

That's the beauty of type C - it will not disconnect when the motor starts.

I think we already had similar discussion in some other thread.
C13 will eventually disconnect if current is higher than rating. Might take more seconds to do so.
Alternative is to change from B13 to B16 or B25. How dangerous would be that, compared to C13?

 

[Spectric]

The issue is that the impedance of the wiring is the governing factor in how much current can flow under a fault condition, if it is border line for the type B then with a type C you could end up with enough current to cause overheating but not enough to cause the protective device to disconnect.

 

[TimV]

A couple of things.
1) This IS a single-phase motor and not a three-phase one, right ? (don't connect a three-phase motor to a single supply)
2) The 13A fuse in the plug is designed NOT to blow unless the current exceeds 50% more than it's rating, which means it won't blow until 20A in the steady state (see https://www.pat-testing-training.net/articles/fuse-operation-characteristics.php) - and it will handle significantly more current for a while. As long as the motor reaches its full speed within a second or two the fuse will probably take the inrush current.
3) on breaker classes. The breaker in the mains wiring is intended to protect the wiring, not the appliances connected to it. As thikone mentions above, class B will take up to 5 times (actually between 3 and 5 times) the current rating - for 10 seconds - so if your breaker is a 20A one it should handle 60-100A during startup. Given the motor nominal current of 8.5A that's probably fine. You could change to class C, which will take between 5 and 10 times the current, but that's only for one second.
4) with all this you're not protecting the motor. It's designed to draw 8.5A so if it takes more, there's a problem, and neither the fuse in the plug nor the breaker will prevent that. This is why you'll eventually need a thermal overload set to 8.5A (or slightly above).

But for a quick test, if it's single phase it should work, just check before you try it that it's running free and is earthed and you can switch it off quick if it doesn't start running quickly (which might indicate a problem with the starting mechanism) - or if there's smoke of course ...

 

[TRITON]

Hi,

I have the above Jointer, I need to test the motor as part of troubleshooting,

It has this motor,

View attachment 180059

Would anything catastrophic happen if I plugged it in directly to the house single phase mains?

I think the mains runs @ 13amps?

Thanking you...

Its going to be fine. I have the same machine and its plugged into a standard uk socket.

Incidentally a kettle(tea/coffee) is usually between 2kw-3kw and draws between 6-12amps.

A machine that is 2kw and 8.5a is low in comparison.

 

[JohnerH]

Its going to be fine. I have the same machine and its plugged into a standard uk socket.

Incidentally a kettle(tea/coffee) is usually between 2kw-3kw and draws between 6-12amps.

A machine that is 2kw and 8.5a is low in comparison.

But I'm stripping it from the casing/housing, hooking the motor up direct to current... to see if it works...

Quite frankly I need to strip the whole thing, this is just the first step.

 

[ChaiLatte]

The inrush current, perhaps 40A, would likely pop the breaker, or blow the plug fuse.

Did I imagine reading in an old book that a way to limit inrush current in something is to wire an old-style incandescent lightbulb in series with the load? Maybe for a bigger motor, a 500W halogen would do the trick.

 

[guineafowl21]

Did I imagine reading in an old book that a way to limit inrush current in something is to wire an old-style incandescent lightbulb in series with the load? Maybe for a bigger motor, a 500W halogen would do the trick.

Tthe old dim bulb test rig. I use one for cautiously powering up repaired/faulty/unknown stuff. Its main use is limiting short circuit current.

 

[JohnerH]

It's alive...

It worked,

9-10s as per the duration of the video, linked it direct to the motor then on and off.

Seems I have more troubleshooting to do upstream.