3 phase switching problem

[eggmonroe]

Hi guys,

I'm new 'round these part, so I'm sorry my first post has to be a cry for help.

I've been running my woodworking machinery on a static 3 phase converter for years. Recently, however, I've aquired a large Dominion tenonning machine which has four seperate 3 phase motors, each switched seperately. To combat the problem, I dug out an old 18 KVA 3ph genny which didn't work (but that's another story). While the genny was being repaired, I decided to test the motors with my converter. I ran the top head motor for about 5 seconds before the machine cut out. Now, even when it's plugged into the (newly repaired) generator I get nothing on any of the motors / switches. Pushing the manual over-rides in the switch box does start the motors however. I've tested my other machines with the generator and it seems fine.

I really don't don't know where to start now, and any help anyone could give me would be hugely appriciated.

Thanks,

Ed.

 

[Engineer54]

Not knowing how these motors on your machine are connected here, but it certainly sounds like you have an overload that's tripped out, maybe all of them .... Don't suppose you have a circuit drawing you can post up here do you?? Makes things so much easier. Even decent shots of the machines control panel (door open) will be of help.

 

[eggmonroe]

Hi,

Thanks for the reply. I'm just off back to the workshop now. I'll get some pics and post them up here.

Cheers,

Ed

 

[eggmonroe]

Sorry, no circuit diagram. Information on Dominion machines is like rocking horse teeth.

OK, here goes the attempted picture of the control panel. Sorry about the picture quality, but my camera is dead so I had to use my phone:

 

[Engineer54]

From what you have described earlier your problem is almost certainly on the control side of this machine. Can't see anything much in this control panel that looks amiss, apart from what looks like a couple of overload trips in the tripped position, but that could be the angle the pic was taken. The motor overloads are the bottom red buttons on the contactors. The red buttons being the ''reset' buttons, try pushing all of them in just to make sure that they are all in the operational position...

 

[netblindpaul]

Which Dominion Tenoner do you have mate?
You have 5 DOL starters in there.
So I suspect that you may have a finish trimming head that has been removed?
DO you have start/stop for each head and an e-stop of not?

I have a good customer with I suspect the same machine!

 

[eggmonroe]

Hmm, they are all "out", when I push them in the is no resistance - they just pop back out again. Should they stay in?

 

[eggmonroe]

Which Dominion Tenoner do you have mate?
You have 5 DOL starters in there.
So I suspect that you may have a finish trimming head that has been removed?
DO you have start/stop for each head and an e-stop of not?

I have a good customer with I suspect the same machine!

Oh, good call. Yeah it's a BXA with the cut-off saw removed. There's a start for each head and one stop button.

 

[netblindpaul]

OK, I know the BXA.

I am not sure about running this m/c on a genny though, that is your call.

Do any motors start?

Have you checked the stop start chain?

Have you tested out the power and control sides of the system?

If so how?

DO the motors run independent of the control side?

 

[eggmonroe]

I have no option but to run the machine off the genny. The last quote I had for a 3ph supply was astronomical. What are the implications of using the generator (bearing in mind most of the work will be using just two of the motors)?

None of the motors start.

All I've checked are the 3 phases running into the machine (using a multimeter across the phases).

I've looked at the stop / start chain and checked the switches for continuity (if that makes sense?)

I don't know what/how to check the power and control sides of the system.

DO the motors run independent of the control side?

I'm not sure what this means. I've just realised I know even less than I thought I did.

I appologise for my ignorance.

Thanks,

Ed.

 

[Darkwood]

As you seem to have power to the feed side of the contactors then as mentioned before it is highly likely the stop/start circuit, check the machine for limit switches to on gaurds etc follow the stop circuit physically if needed to see where it goes this may highlight a limit or over-run switch you missed, they can be a biatch to find sometimes as they can be part of a gaurd hinge etc so not also visually obvious.... well its a start and thats where id be looking first.

 

[eggmonroe]

OK, thanks. I'll give that a go.

 

[netblindpaul]

darkwood,
Good point, but doubtful on a Dominion Tenoner TBH!
Too old, not CE marked and not compliant with PUWER98 as shipped.
IIRC Dominion went under prior to all this guard interlocks nonsense!

 

[Darkwood]

well was shot in dark as not familiar with said machine myself but you never know?, might have been customised a tad :O

 

[eggmonroe]

Guys,

Thanks so much for all your help. I tested everything and it all pinged out OK.

Turns out the problem was genny related after all. It was delivering 415V, but not at 50HZ. Fiddled with it last night and managed to get everything going. Quite why the other machines were working is a mystery to me, but then this three phase business always has been:bucktooth:.

Thanks once again,

Ed.