Dol starter

[Ch1]

Never really touched on motors always been domestic, any ways il cut to the chase, got a job dol starter 3ph not stopping on em stop button, am I right in assuming it can only be the dol stater is nakered, and just replace it, or could it be deeper and be overload setting wrong etc etc. Also to set the new overload setting to I take the motor current and set it at 110 percent of that?

 

[LankyWill]

id wouldn't be so presumptuous on the faulty dol starter, fault find the whole setup. Just use the already set overload on the original starter.

 

[LankyWill]

could be a faulty stop start switch also

 

[Ch1]

id wouldn't be so presumptuous on the faulty dol starter, fault find the whole setup. Just use the already set overload on the original starter.

Ok, he has told me it starts fine but has to isolate it by killing the power at the breaker at the other side of the unit.

 

[LankyWill]

sounds like the switch isn't disconnecting the coil, or the coil is sticking. Just use a continuity tester to check the switch is functioning correctly.

 

[Ch1]

could be a faulty stop start switch also

Start/stop switch is built into the the contactor am I right? For the price I may aswell replace the whole unit considering its age etc.

 

[Ch1]

Start/stop switch is built into the the contactor am I right? For the price I may aswell replace the whole unit considering its age etc.

OK thanks.

 

[LankyWill]

I went to a fault on a 1920's air compressor that had a 40 year old contactor, the contactor was fine and tripped due to loss of phase(DNO CABLE). Simple reset was all it needed after i found the obscure button. Dont be afraid!!! fault find and discover the problem, you will end up making more work for yourself if its a faulty switch plus the COST.

 

[LankyWill]

The dol starter might even be integrated on the machine itself.

 

[westward10]

I can only see the starter as being faulty in some way, if you know your way around one it may or not be repairable.

 

[Darkwood]

Reading your post I get chills, I'm not trying to disrespect you in any way as your most likely fully competent in your comfort zone but you shouldn't be entertaining doing any such work without the knowledge and training required, motor controls and circuits can be simple in operation yet complex in there fault finding or vice versa, getting it wrong can be very costly, you clealy are delving into areas you don't have any experience in so as an Electrical Engineer who designs builds and faults control system for machinery I hope you take my words wisely as I see the results of eager Electricians having a go at the Industrial control, I have seen companies go bankrupt from stepping into this area and making basic errors hence my response.
I'll pop a few queries and try to help here ..

Is the control circuit independent of the motor supply circuit?
Is it an E-stop or a functional stop (the shape of the button is not always what you may be led to believe).
Have you done any tests on the control circuit to establish the circuit is reacting to its button status?
Is the contactor welded in?... visual observation on this one normally.
Has the operator given any info that may help in diagnosing the problem?
If the DOL starter is a all in one unit, does the mechanics of the stop button actually press the stop on the overload as these can sometimes become warn or mis-aligned ..simple check is remove start/stop cover and press the buttons manually - this only relates to buttons that are just physical extensions and no wiring on them.

 

[Ch1]

Reading your post I get chills, I'm not trying to disrespect you in any way as your most likely fully competent in your comfort zone but you shouldn't be entertaining doing any such work without the knowledge and training required, motor controls and circuits can be simple in operation yet complex in there fault finding or vice versa, getting it wrong can be very costly, you clealy are delving into areas you don't have any experience in so as an Electrical Engineer who designs builds and faults control system for machinery I hope you take my words wisely as I see the results of eager Electricians having a go at the Industrial control, I have seen companies go bankrupt from stepping into this area and making basic errors hence my response.
I'll pop a few queries and try to help here ..

Is the control circuit independent of the motor supply circuit?
Is it an E-stop or a functional stop (the shape of the button is not always what you may be led to believe).
Have you done any tests on the control circuit to establish the circuit is reacting to its button status?
Is the contactor welded in?... visual observation on this one normally.
Has the operator given any info that may help in diagnosing the problem?
If the DOL starter is a all in one unit, does the mechanics of the stop button actually press the stop on the overload as these can sometimes become warn or mis-aligned ..simple check is remove start/stop cover and press the buttons manually - this only relates to buttons that are just physical extensions and no wiring on them.

Thanks for your reply I do agree with you, I normally stay away from this kind of stuff but it's for a friend, anything other than a dol I wouldn't get into tbh. I have the basic knowledge of this sort of thing but just wanted to check as this isn't really my area of expertise, nobody knows everything hence why I'm asking on here. Just incase there's something iv missed like you said the obvious things. Control circuit is independent. Functional stop, and I assume the contactor isn't welded in as it doesn't re-energise once power is restored, I haven't been to see it yet just from what he has said so I just wanted to ask on here before I go really.

 

[Lagentium]

Slightly disagree Darkwood, most tests can be done with the starter safely isolated to find the fault. If he doesn't go jamming a screwdriver in while energised I can't see the problem, as you have to begin somewhere with experience. I'm all for safety, but equally against a nanny state.

 

[Darkwood]

Slightly disagree Darkwood, most tests can be done with the starter safely isolated to find the fault. If he doesn't go jamming a screwdriver in while energised I can't see the problem, as you have to begin somewhere with experience. I'm all for safety, but equally against a nanny state.

I can see where your coming from but when it comes to motor and controls, it's not just a matter of checking functional operation, a good background knowledge is required to pick up on things that a Newby may miss, it's these little things that can cost a company down time but as the op has explained it's just for a mate and not his usual direction then not a problem to help out in my opinion... I posted from 28yrs of experience of seeing very basic errors costing big losses for companies, I may sound like I'm fear mongering but this area of electrics is a totally different course and diploma and for very good reasons.