3 phase motor wiring

[clueless77]

Not the usual star or delta question. Motor is a 3 phase dual voltage 3.2 hp AEG motor on a lathe.
Got an inverter after making sure motor was dual voltage, then opened the wiring cover on the motor and well, FMG. Was expecting the same as all the threads i'd read but got this. I was hoping to just wire straight to the motor. The 3 diagrams are what I found under the motor connection cover. I know one is the star/delta and reversing connections, one looks like the motor t.o.c and the other is the motor braking. Question is, what do I need to do to just wire into the motor? Is it just a case of pulling all the wires out and wiring up to the inverter or will I need to bypass the other terminal block connections? Any suggestions would be really appreciated. Cheers.

 

[Hopefuldave]

The first sheet, delta (low voltage assuming you're feeding it 240v) from the.top row, the.VFD will take care of reversing and braking. You might want to use the thermal switch if you're likely.to run at low frequency much, the fan won't be spinning as fast and the.motor can overheat - put it in series with the common of your fwd/stop/reverse switch so it kills the drive, or use it to control a relay running a cooling fan. A lot of VFDs have.a relay on board that you can set to.open over a 'supervisory' frequency and switch off an external fan to keep the motor cool at low revs / when.stopped.

 

[clueless77]

Half way down a bottle of plonk now so will sleep on it. Thanks for the reply.

 

[Luke]

Looks like there's a rectifier to control the brake coil, so you'll need to supply it with AC to lift the brake. This may need 230V or 400V, depending on the rectifier.

Depending on the inverter, it should be possible to get the inverter to monitor the over-temperature switch, and also control a contactor to energise the brake as part of the enable sequence.

Luke

 

[daleyd]

Like Luke says above, it's a motor with a brake attached and a temperature sensor in the windings.(usually a thermistor)

If you look at the motor it will be a bit longer than normal to house the brake, and you sometimes get a little lever to engage/disengage the brake manually, but not always.

If you don't need the brake function you can generally mechanically adjust it so that it never comes on, or as said above you can wire it in to the inverter to release when the drive is enabled. To adjust it remove the end cover over the fan and it's usually under there. Adjust the nuts that hold the plates apart so that there is a gap between the plates and the spindle is free to turn by hand.

If you use the brake and you have a heavy load with a fair bit of inertia and you take power off the drive to stop (Coast to a stop) then you may have a problem as the brake will engage - they are generally only holding brakes for when the drive is at or close to standstill.

If it's a used one and you want to keep the brake function then it may be worth checking the gap when disengaged and blowing any dirt out from the plates, this can cause issues if not set correctly(they can drag and cause the motor to overheat) info is generally available from manufacturer website(eg sew/weg etc)

 

[daleyd]

I don't know the manufacturer of your motor but here is some info on the weg ones, they are all generally similar.

Good luck!

http://ecatalog.weg.net/files/wegne...aintenance-manual-50021973-manual-english.pdf

 

[clueless77]

That link is spot on, the second diagram is the same as mine although a different orientation of the connections. The motor is an AEG but their site isn't as informative as the WEG site. I think I will nip into the inverter suppliers with the lathe manual and see what my easiest option is, they said I could wire it into the distribution board of the lathe but said it was more complicated than straight to motor, after looking at the motor connections it may be the way to go. Thanks for all the replies.

 

[daleyd]

If the motor you are replacing doesn't have a brake I'd be tempted to disengage it mechanically. If your inverter doesn't have an input for thermal overload then just ignore that connection, or you could wire it up to a relay/light to give overheat indication if you were that way inclined. I don't know how you intend to wire it all up but you could also put it in series with the run signal to stop the inverter in case of overheat.

 

[clueless77]

Went into Newton Tesla this afternoon, went through the diagrams and I have a couple of options and it is all clearer in my mind now. Very helpful people at Newton Tesla would recommend them any time, (no connection other than satisfied customer). Thanks for the input and that link, much appreciated.

 

[daleyd]

No problem don't forget to keep is up to date on how you did it!

 

[clueless77]

Forgot to update this, sorry. Well for some reason I didn't do anything that I was told and in a fit of brilliance decided to put 240v to the motor brake, nothing else connected thankfully. At first it made a fizz, crackle and then tick, smelled like really burnt caramel. As soon as my reactions would let me I killed the power and then thought, "why didn't I put that through the rectifier before the brake?". Anyway, damage done I removed the motor and took the brake mech completely off. I wired the motor up to the inverter and powered up, thankfully it works a treat. Lesson learned, don't tinker when tired or clueless.