Auto Star/Delta Starter Q/N

[Bobeto]

Hello to everybody, I`m new here with pretty basic knowledge bout all that three phase electrical thing....
However I am here to ask you for a little help to source a part and/or eventually wire it.
So I`ve bought myself a big three phase compressor with Auto Star/Delta Starter. But there is a missing part in the Auto Star/Delta Starter box. I get in touch with the manufacturer of the air compressor (ABAC) and they sent me a wiring diagram of that "auto star/delta starter box (pretty basic) and what they said was I am missing the transformer. Long story short the guy said it will either be 240v or 24v and I can check this by checking the coil voltage of the contactors and source the transformer from a good electrical retailer. But what contactors and how to check I don`t have any idea.

P.S. Unfortunately as a new member here I am not allowed to post pics or links before I make 6 posts. That`s why I can`t upload pics to show you the wiring diagram and the "auto star/delta starter box"


Cheers
Bobby

 

[snowhead]

First I asume you have a 3 phase supply to connect it to
Second that you have someone competent to connect it up for you.

There will be 3 contactors in the box.
The Coil is at the back of the contactor and will have either 240v or 24v written on it or a tag with it on.

 

[Gage]

Above. Just get someone competent in to do this for you. If you're really desperate get a 24v DC PSU and try it, if it doesn't pull the contactor in then obviously it's 240v. If you don't understand a thing I'm saying, definitely get someone else.

 

[Bobeto]

Thanks guys,
I will do. I`m too afraid from the electricity let alone three phase 415V......there will be no forgiveness if I messed up something.....

 

[Bobeto]

I just want to know what is going on. I like to learn new stuff

 

[Bobeto]

Also I don`t like when someone see that you don`t have a clue and take you for a ride......you know what I mean.

 

[Bobeto]

So here are the pics. The wiring diagram of the box and a pic of the boxes internals and the missing part (empty space)


Thanks
Bobby

 

[Marvo]

the guy said it will either be 240v or 24v

'The guy' is lying to you, the transformer should be 400V primary and the secondary will need to be whatever the voltage of the contactor coils. If you dismount a contactor from its rail you should see the coil voltage marked somewhere on it.


I'd suggest you source the transformer and get someone competent to install it and test/check the wiring before you connect the supply. It's going to be a costly, not to mention possible dangerous exercise if there's a problem.

 

[Bobeto]

You mean the one that is marked as "KML" and in the diagram they call it main power contactor. Is that right.
I definitely will call an electrician but I wanted to source the transformer myself before that.

Thanks
Bobby

 

[Gage]

You mean the one that is marked as "KML" and in the diagram they call it main power contactor. Is that right.
I definitely will call an electrician but I wanted to source the transformer myself before that.

Thanks
Bobby

Any of them.

 

[Bobeto]

Thanks, Gage.
One more q/n. How can I choose the power rating ( VA). In RS Components | Electronic and Electrical Components the transformers have VA rating from 50VA to couple hundred VA`s. The motor on the compressor is 10HP (7.5 kW).

Thanks
Bobby

 

[Gage]

The transformer isn't powering the Motor, it's powering the contactor coils, a solenoid, pressure switch and a few indication lamps bla bla bla. Find out how much amperage the components after the transformer draw. Convert your amps to VA and choose your tranny accordingly.

 

[Knobhead]

Simple. Add some garlic to the spaghetti all will be fine. You don't give anywhere near enough information. I could have a guess, as many on here will but I don't like making mistakes. coil voltage, supply voltage and coil loading are needed to give a reasonable answer.

 

[Gage]

I don't like making mistakes.

Chose the wrong career it would seem. oliceman:

 

[Gage]

I also have to say I really hate it when everything is squeezed into one drawing haha. Makes things seem like wiring diagrams to the incompetent.

 

[Bobeto]

Well, thanks for the advice. I`ll see if there is any sign on the components for amperage they may consume and calculate it from there. If not I`ll give up and let the electrician check what kind of transformer I have to buy.

Thanks a lot mate.

 

[Knobhead]

Chose the wrong career it would seem. oliceman:

You forget something kid. I've served my 40 years sentence. Out on licence now.

 

[Gage]

You forget something kid. I've served my 40 years sentence. Out on licence now.

Just beginning mine, no probation as usual.

 

[snowhead]

either (most likely 24v)
Transformer 415V to 24V 50VA single voltage | Eastern Transformers

or
Transformer 415V to 240V 50VA single voltage | Eastern Transformers

 

[Knobhead]

And if the loading isn't 50VA ?

 

[snowhead]

And if the loading isn't 50VA ?

They'll be wrong, but the competent person will be able to check the correct loading.

It's only for 3 small contactor coils.

 

[Gage]

If it's 240v then 50VA will give him around 0.2A, which from the drawing isn't going to cut it IMO. If it's 24v then he'll get around 2A with 50VA, which may JUST cut it depending on the Solenoid rating but I doubt it when you include the lamps and such. So.....probably not 50VA he's wanting.

- - - Updated - - -

They'll be wrong, but the competent person will be able to check the correct loading.

It's only for 3 small contactor coils.

And Solenoid, Lamps, and other switches. Look at the drawing.

 

[Bobeto]

Hi guys,
So have some more info and pics from the labels of the components.
So the contaktors KMS,KMT,KML are the same so see the attached pic:



The FR - thermal cutout:



The KT1 -Delta-star timer is 24-230V AC/DC, 5A
The pressure valve (solenoid) is: 110V/Hz50, VA 10 Hold, VA 16 Inrush
The bulbs are quite small and there are no parameters written on them.

 

[Bobeto]

Hiya,
Final update on the topic, hopefully.
I got in touch with the Italian manufacturer of that box and ask them nicely for specs of that very transformer and they were very kind and replay immediately.
So the transformer should be with Input Voltage 415V, Output Voltage 0/110V and VA rating of 80VA.

I have one more q/n to the specialists here. The closest transformer is 100VA rating. Is it a problem if I fit 100VA or 150VA transformer instead of 80VA one?

Thanks
Bobby