DOL starter 415V coil

[Hutch118]

Anyone tell me what Ive done wrong here lads?

Wired up a starter today, 2 DOL contactors with 415V coils fed through two Telemec Motor Overload units sitting side by side in an enclosure.

Wired up from the Red phase through a Stop and Start button back through A2 with hold on contact 13/14 used and A1 onto Blue phase. No O/L as its thru the Motor O/L unit above the contactor. Press the start and 'bang' blew the main fuses. it was like a dead short. frustrated as its just a simple circuit.

Checked all the wiring and its fine, looked for diagrams and checked and its fine. Where have I gone wrong???What have I done wrong here????

 

[Marvo]

Was the motor connected or were you just testing the DOL starter on its own?

Sounds like now would be a good time to dust off the tester.

 

[Hutch118]

Wasnt connected to the motors Marvo, i checked all the wiring as per drawings and its correct but still blows the fuses as in a short. I cannot fathom out a stupid wee fault like this. Phasing is correct, all control wiring is correct. I am at my wits end. I cant help thinking its something further back down the line but we use the supply elesewhere on other starter panels with no hassles.

 

[telectrix]

start with the basics. power off ohm meter across A!-A2. see if there's a short across the coil/s. then progress from there.

 

[Hutch118]

Done that mate, the two coils are fine. Its weird because according to any diagram Ive looked at, the wiring Ive done is exactly as stated, and by the way, Ive done this work for years which makes it even worse for me!!!!, I cannot figure out why it blows fuses, I had to walk away from it earlier, I was so hacked off.

 

[telectrix]

what's on the load side of the contactor/s?

 

[Marvo]

Hmmm, I thought of a stupid question and I'm going to ask it anyway. Are you sure the starter arrangement with 2 x contactors isn't a star/delta starter with the link wires still across one of the contactors?.

With your post count you shouldn't have any problems if you want to attach a photo or two to give us a better idea of your setup.

 

[Hutch118]

Its two dol contactors side by side lads controlling two motors, they are seperate from each other. wiring is the same for both, and both come thru motor protection breakers from Telemec. All im doing is trying to energise the two contactors both with 415V coils thru a start and stop button, easy peasy or so you would think. Its so easy Im stumped !!!!

 

[telectrix]

bet it's so simple that a 2nd look will spot it right away.

 

[Hutch118]

I hope so Teletrix, I fkn hope so. Thanks for replying as well

 

[44ALLAN]

Its two dol contactors side by side lads controlling two motors, they are seperate from each other. wiring is the same for both, and both come thru motor protection breakers from Telemec. All im doing is trying to energise the two contactors both with 415V coils thru a start and stop button, easy peasy or so you would think. Its so easy Im stumped !!!!

Check both A2's on each coil are fed/linked from the same phase for starters.
Then make sure each control circuit is on the same phase too and ends up at A1.
Sounds like it's crossed somewhere and giving you a short.............I am on my umpteenth bevvy btw.

Don't try this at home kid's lol

 

[Jimsparky]

Another one is make sure the contactors are 415v coil and you've not been given or fitted a different voltage by mistake.
Jim

 

[Hutch118]

Cheers lads, they are both 415v coils and my thoughts are that somethings crossed giving me a short. check in the morning.

 

[Knobhead]

Post a photograph or two.

Out of interest is this a reversing starter or two drives?

If the fuses blow when the contactor closes it points to the motor terminal side. Had the fault been on the control the MCB's would have tripped.

 

[Hutch118]

It's two separate motors Tony, one a 7.5kw and the other a 1.1kw. Just a simple control circuit.

 

[netblindpaul]

Well I won't go into the bit of standards that prevents 400V control on 2 motors for compliance with current standards & legislation then.

 

[Hutch118]

Thanks for that wee gem of advice Paul, this is why I rarely come onto this forum for info !!!

Most of the folk are very genuine and helpful while other 'experts' go out their way to make statements like they are know it all. Why make a statement like that? If you want to help, then please help.

If Ive done something wrong, then point out why and where I can get the info so I understand why I went wrong. Is that not easier for you???

 

[plugsandsparks]

FWIW, if it was me i would check the coil voltage first as it wont be the first time..
second i would double check the wiring by "belling", i.e. ignoring any wire numbers just in case a bit of brain fade when numbering (wouldn't be the first time).
Then i would check the resistance of the coil to make sure someone was not having a laugh and marked up a 24V coil as 400V ..)

 

[Darkwood]

Right .... the main issue with simple problems is they sometimes elude you so what i suggest is you take a picture of the set-up im sure it will be clear for us to head you in the correct direction...

If you have not loads connected to contactors and it shorts when hitting start button then it points to a simple wiring issue in your control circuit either through oversight or lack of understanding and you seem clearly creating a short when energising the coil... it may be down to confusion here .... pic of the wiring and contactor will help with indicators of any wires going out of view.

 

[Darkwood]

Thanks for that wee gem of advice Paul, this is why I rarely come onto this forum for info !!!

Most of the folk are very genuine and helpful while other 'experts' go out their way to make statements like they are know it all. Why make a statement like that? If you want to help, then please help.

If Ive done something wrong, then point out why and where I can get the info so I understand why I went wrong. Is that not easier for you???

Although you have not suggested you have exported your control circuit he raises a good point if you have ... if your start stop are remote and you are controlling the coil with 400v then you will be in a possible contravention of regulations ... this is not part of BS7671 and if your don't know what regs it falls within then you shouldn't even be touching this. You shouldn't take offense at such a post as it states a good point if you are offended then reply that you are fully aware and his concerns are not the case or we will obviously question your competence in such an area.