Direct on line starter help

[fatfranky]

I wonder if anyone can help me, I have a workshop machine with a 1/2HP 3 phase motor that I run off a static phase converter. Since the day I got the machine the starter has been faulty, it will not start the machine, if I remove the front cover and buttons and manually press the contactor it spins fine.

I’m looking at a replacement starter but what “overload amperage” should I be specifying? I cannot see any ratings on the old MEM starter unless I’m not looking in the right place

many thanks in advance

 

[carbon]

Motor current looks like 1.5 amps. Do you have a picture of the insides of the starter

 

[Pete.]

Is the static converter putting out 415v or 240v 3 phase? If it's 415v try putting the starter coil on the non-generated phase.

 

[brightspark]

take the cover off theres a green knob that alters the amperage to see what size . to be honest just fit a triple pole isolator switch I wouldn't bother with overloads at that size of motor. its not as if your going to leave it unattended and it overloads you can feel the motor to see if its getting hot

 

[fatfranky]

Pete

Converter is 415v, I’ve tried swapping the phases round and it’s made no difference

Carbon

photos below

Brightspark

to be honest I was just replacing like for like

I don’t know what that switch is? Could you provide a link please

 

[Ton-up]

On the side of the contactor under the green knob is an arrow pointing at a scale. That will tell you amp rating of overload.

 

[brightspark]

Pete

Converter is 415v, I’ve tried swapping the phases round and it’s made no difference

Carbon

photos below

View attachment 219790 View attachment 219791 View attachment 219792

Brightspark

to be honest I was just replacing like for like

I don’t know what that switch is? Could you provide a link please

its just an on off switch rotary. what machine is it on https://www.tlc-direct.co.uk/Produc...MImKuVkJvD6AIViLTtCh0EjwYoEAQYAiABEgKMIvD_BwE

 

[fatfranky]

It’s on a pullmax reciprocating machine

 

[brightspark]

whats the switch on the left of it

 

[fatfranky]

It has a 2 speed motor ( one of the reasons why I didn’t run it off a VFD

 

[Agroshield]

...if I remove the front cover and buttons and manually press the contactor it spins fine.

Some of the older MEM stuff has asbestos around the overload coils (bottom left, second photo) so assess and treat accordingly.

I do not think the green button presses directly on the contactor. I think it closes a momentary switch that energises the coil and sucks in the contactor. It might be the 'bootstrap' part of the circuit that is faulty.

 

[fatfranky]

Some of the older MEM stuff has asbestos around the overload coils (bottom left, second photo) so assess and treat accordingly.

I do not think the green button presses directly on the contactor. I think it closes a momentary switch that energises the coil and sucks in the contactor. It might be the 'bootstrap' part of the circuit that is faulty.

Thanks

Forgive my stupidity but what do you mean by “bootstrap”

Thanks

 

[Seadog]

The green button closes a contact pair that energises the coil. This closes a second set of contacts which "lock on" to keep power to the coil. When the green button is release the initial pair of contacts open. Your stop button is wired in series with the second pair of contacts so that when pushed, which breaks the circuit, the power to the coils is lost and the contactor opens.

 

[Agroshield]

Forgive my stupidity but what do you mean by “bootstrap”

Seadog described it perfectly.

In operation, the contactor keeps itself closed (and will open on loss of power, hence it has NVR no volt release built-in), but you need a bit of smartness to be able to close it in the first place.

Bootstrap is from computers where a little bootstrap program runs automatically when you switch on the computer. This then loads the much bigger main operating system.

 

[Munkul]

If I were in your shoes I'd just throw money at the problem.

https://uk.rs-online.com/web/p/dol-...ykpgl6xeocl70TOHq2IaAtByEALw_wcB&gclsrc=aw.ds

 

[Seadog]

Bootstrap is from computers

But originally from "The Surprising Adventures of Baron Munchausen" where he pulls himself out of a swamp by his pulling on each of his bootstraps.

 

[fatfranky]

Thanks for all the replies guys, replacement ordered

 

[fatfranky]

Once again, thanks for the help, new starter arrived this morning and I’ve fitted it tonight, works perfect.