Starters and motors

[i=p/u]

was looking at a motor the other day and when I measured across all I got was 230v to Earth but not 400v between.

 

[i=p/u]

Rating ate.

 

[i=p/u]

What's this?

 

[davesparks]

View attachment 27775What's this?

A PCB with some wires connected to it.

 

[Pete999]

was looking at a motor the other day and when I measured across all I got was 230v to Earth but not 400v between.

Across what and between what?

 

[Darkwood]

What controls the motor? .... DOL, VSD, Star/Delta, Soft Start etc etc?
Has it got speed control?
What meter are you using to get your voltage?
What's the nature of this post... is something wrong with the motor or its operation?

 

[D Skelton]

The links are arranged in star formation. If you measure between each incoming phase to the star point of course you're only going to get 230V. That is of course assuming direct connection to the supply. What voltage are you getting between the incoming phase terminals? How is the motor started?

 

[ipf]

View attachment 27774Rating ate.

Did it taste good?

 

[i=p/u]

Ate screws and all.. Ipf

 

[i=p/u]

What controls the motor? .... DOL, VSD, Star/Delta, Soft Start etc etc?
Has it got speed control?
What meter are you using to get your voltage?
What's the nature of this post... is something wrong with the motor or its operation?

I know nothing about controls and motors. I measured 400v at isolator , which then goes to id say is a starter of some sort (pic). I then measured 230v at motor housing. I used martingale gs38 tester

 

[VoltzElectrical]

I know nothing about controls and motors.

Neither do I, that's why I leave it to others!

 

[davesparks]

I know nothing about controls and motors.

Then leave it alone and advise your client to hire someone who does

 

[baldsparkies]

I know nothing about controls and motors.

Sorry, but having said that !!
What exactly are you trying to achieve here ??
I think you should put that cover back on to be honest and get someone with you who does know about motors and control gear.

 

[i=p/u]

Guys and divas , I only check power at devices after that the boss sends it back for specialist which I asumme in this case is an electrical engineer .

 

[i=p/u]

Haven't even told you about the caretaker and your telling me to put cover on lol.

 

[i=p/u]

Neither do I, that's why I leave it to others!

Agree totally

 

[Marvo]

If it's supplied by a variable frequency drive there's a good chance your tester won't be able to make sense of the supply at the motor due to the high carrier/switching frequencies.

 

[i=p/u]

Is that not a drive in the pic Marvi

 

[Marvo]

I wasn't entirely sure what that was in the pic. Have you got another pic taken from a bit further away?

 

[i=p/u]

If it's supplied by a variable frequency drive there's a good chance your tester won't be able to make sense of the supply at the motor due to the high carrier/switching frequencies.

I measured 230v at all points on motor to earth but nothing between connections

 

[Marvo]

Was the motor running?

 

[davesparks]

Guys and divas , I only check power at devices after that the boss sends it back for specialist which I asumme in this case is an electrical engineer .

If you don't understand the basics of motor control then how do you know what you are testing for or what test equipment is appropriate/safe to use?

 

[i=p/u]

Dave not my job now so fuk it . Just a little interested .

 

[elevate]

Its not a drive in the picture, the circuit board looks like some sort of RC circuit, could be for soft start or noise suppression. Any wiring diagrams?

 

[i=p/u]

And out of interest its a band saw. With two emergency stops onit plus start stop button

 

[Marvo]

It's not a drive and it's a bit elaborate for a suppression board plus there's no ground on it. Maybe soft start but I can only see 2x components on the heat sink so also unlikely.

You didn't say if the motor was running or not. What was the fault they reported and what was the application or machine it was a part of?

 

[Silly Sausage]

View attachment 27778 Dave not my job now so fuk it . Just a little interested .

Who pulled all the inards out?

 

[Marvo]

My tying is too slow, it's probably the control board for the interlocks / estop etc. In that case the motor looks like it's direct on line so I give up about your weird test results in that case.

 

[i=p/u]

The fault was bandsaw not working. It also has a dust extractor tapped off it

 

[i=p/u]

But as said why only getting 230v motor connections,

why nit not just break live with e stops , forget control boards ...

 

[Silly Sausage]

The fault was bandsaw not working. It also has a dust extractor tapped off it

1: Determine make and model of said saw.
2: Ask Maintenance if they've got a manual for it.
if not,
3: Get online and see if you can find one.
if not .......

 

[Marvo]

The only explanation of getting 230v from all terminals to earth and 0 v between the terminals themselves is that there's only asingle phase being supplied to the motor. That's the easy bit, the difficult bit is figuring what's causing that condition. Maybe the contactor was not energised but one of the contacts is welded closed due to a fault current that occurred previously but then the question becomes what was the earth or the s/c fault.

 

[netblindpaul]

That's a Klinger & Born DOL starter with O/L & d.c. injection brake.

 

[ipf]

The only explanation of getting 230v from all terminals to earth and 0 v between the terminals themselves is that there's only asingle phase being supplied to the motor. That's the easy bit, the difficult bit is figuring what's causing that condition. Maybe the contactor was not energised but one of the contacts is welded closed due to a fault current that occurred previously but then the question becomes what was the earth or the s/c fault.

Just going to ask if he'd checked the fuses:icon12:

 

[i=p/u]

Tell me more netball

 

[Marvo]

Thanks Paul, I was hoping someone would recognise it.

 

[netblindpaul]

It's what I do for a living remember, not recognising, but machinery stuff, from fixing, to designing, to consulting on CE & PUWER in the main.

 

[i=p/u]

Which fuses Ipf ? On the circuit board? Yes there's one which Belleyed out.

theres 400v at dol starter but only 230v at motor casing.

when you hit the start button , the extractor kicks in, the pulls out again and there's a burrRRrr sound but blade don't rotate.

and believe me when I say I ain't fixing this . But would love too some day lol

 

[ipf]

Which fuses Ipf ? On the circuit board? Yes there's one which Belleyed out.

theres 400v at sol starter but on 230v at motor casing

Fair do's.....but we're all guessing a bit at fault finding without being on the spot.

 

[i=p/u]

So why pcb board netball? What we got here

 

[Darkwood]

When you test the motor have you pressed the start or are you testing it when it supposed to be off, some old machinery only had switching on 2 phase leave one phase energised and also O/L motor protection can be found on 2ph only, it can be a number of reasons why your getting your readings and without knowledge and experience you need to leave well alone, you'll be surprised how fast not knowing what your doing can escalate the costs and most of it probably caused by yourself not following procedure for checking and testing motors and control circuits.

It would probably take me less than 5 minutes to test and identify the issue while not causing any further damage but this is because this is what I do for a living ... sometimes enjoyable and others not (-4 degrees monday morning at stone yard chipping ice out of a pump I dismantled comes to mind)...

I would in your case put it back as found and advise to call in someone experienced in this field because I see the problems caused by curious sparks trying to solve these problems and it usually isn't pretty and can be costly to said sparks after I've done a report.

I would need to be onsite to resolve this for you as its very difficult to advise on the forum only .... what I find will denote the actions and tests I carry out.

PS when you here the motor buzzing you could be causing damage to it which may require a rewind or new motor whichever may be most cost effective.

Edit just noted you said your not getting involved any further ...

 

[i=p/u]

The squirrel cage is a robust motor hahahahhahahahhhahahah

 

[i=p/u]

I don't know , I just had nosey.

 

[Darkwood]

The squirrel cage is a robust motor hahahahhahahahhhahahah

Any motor in good condition will survive if the protection is set right and adequate ... the problem is this is not the case with half the crap out there .... ...if the motor hums and doesn't move you are turning the windings into a heater coil tht will self destruct if not stopped ( In the case of a standard squirrel cage)

 

[telectrix]

But as said why only getting 230v motor connections,

why nit not just break live with e stops , forget control boards ...

stupid boy, pike.

 

[ElectroChem]

Any motor in good condition will survive if the protection is set right and adequate ... the problem is this is not the case with half the crap out there .... ...if the motor hums and doesn't move you are turning the windings into a heater coil tht will self destruct if not stopped ( In the case of a standard squirrel cage)

If I had a penny for every time we've attended a burnt out motor to find the TOL either cranked up to max or absent...

I still couldn't buy anything because I'm in Australia and we haven't had pennies since 1950 something, dammit.

 

[jamie-spark]

Deleted oops

 

[Jonspark]

looking at the motor name plate thats a hazardous area motor suitable for dust environments, and as such should you be running it without the lid on?

 

[Lucien Nunes]

why nit not just break live with e stops , forget control boards ...��

The injection brake uses phase-angle controlled rectification to pass DC through the stator winding, creating a stationary magnetic flux instead of a rotating one. The current induced in the rotor cage is also stationary in space and like an eddy-current brake this produces torque in the opposite direction to rotation, rapidly slowing the machine as though there was a physical brake on the shaft. Braking is mandatory on certain kinds of machinery where there is increased risk if the machine is allowed to coast down to a stop, so it was totally relevant to mention that this is on a bandsaw.

As for your first Q - 230V everywhere but no 400, suggests one phase only is connected. Note that the brake is not a full 3-phase bridge and will produce some funny-looking readings at the motor terminal.

Oops double post... dunno how that happens.

 

[R G]

I was told of a similar type of motors on later underground trains , where they have a selector for rheostat 1, 2 and hold , the motors are 630v DC , and they become generators on braking and this generated voltage is sent to the other motor in reverse windings , and thats the noise you hear when approaching before application of the main braking system ...