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Discussion Starter · #1 ·
We have some old ASCO ATS' at work and the ATS for the Fire pump has been fried twice. The circuit board for control is what is getting cooked.

Here is the scenario:

Contractor is replacing our generators and switch board #1 (main switchboard), they removed the normal source for this ATS from the switchboard and tied it directly to the secondary of our MV transformer, when they put the ATS back into Auto from by-pass the control board burns up.

Now here is the kicker, if the contractor hooks the ATS to a temporary generator (temp generator running) as normal source, everything works perfectly fine.

ASCO is onsite also and is stumped. I'm going into work now to take a look at the problem and try and figure it out. This one has me baffled but then again, I haven't seen anything yet, this is just my supervisor explaining things to me over the phone.

Any ideas are welcome at this point. When I get to work I can take pictures if necessary.
 

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System Voltage? 480? 600? 208? Switching neutral or not?
 

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Discussion Starter · #3 ·
System voltage is 480 wye, no neutral switching, actually no neutral at all, just ground. ATS is grounded to building steel and UFER.
 

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Then you are not dealing with wye. No neutral means you are dealing with 480 delta.
 

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Has ASCO serviced the ATS, checked the clearing contacts. The last few ASCO techs I worked with were USELESS, flew in from FLorida and did not properly adjust the ATS contacts (they did not know) burnt the controller and coil.

We had a control panel they had a coil we replaced them, serviced the ATS PROPERLY and it worked. While we were doing this they told the customer they ATS needed to be replaced.

A week later were installed the new ATS, due to their lack of knowledge of their product.
 

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Discussion Starter · #8 ·
Update: I found the problem.

Once I got onsite I found the Normal source ground connected to SWBD#1, which was being fed from utility transformer #3 via a tie breaker (SWBD#3) with no ground/neutral :eek:. The ATS in question was temporarily being fed from utility transformer #1 without the ground connected.

I disconnected the the ground from SWBD#1 inside the ATS and connected the ground from utility transformer #1, replaced the circuit board and the rectifier assembly on the MUS (Multi Use switch) and everything worked perfectly. We went from generator to normal power both manually and in auto mode. :thumbup:

The only thing I can think of is I was getting some sort of anomaly through the grounds, since they were coming from different sources.

And yes the ASCO tech wasn't much help except for providing replacement parts.

Here is the model of the ATS:


The burned circuit board:
 

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Then you are not dealing with wye. No neutral means you are dealing with 480 delta.
No, that isn't always the case. We just installed a 400amp with straight 480 and a ground. It was a WYE system. The POCO demanded a neutral that we just terminated as a ground.
 

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This forum got me again. I resurrected an old post. These should be closed after a year or two.
Some sites have a " you are respnding to a thread that is over a year old. Do you wish to proceed?" warning when you click "post reply". Can't we have something like that here?
 

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Some sites have a " you are respnding to a thread that is over a year old. Do you wish to proceed?" warning when you click "post reply". Can't we have something like that here?
I agree. The moderator promised me a similar action, but never has months ago.
I have learned to look at the original post date if there is over 20 replies.
 

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IBEW 6 volts to lightning bolts
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No, that isn't always the case. We just installed a 400amp with straight 480 and a ground. It was a WYE system. The POCO demanded a neutral that we just terminated as a ground.
Yes you need to bond the neutral or you will have a hard time clearing a ground fault upstream.


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