Motor contactor

Grallert · November 4

Good afternoon folks.

I'm looking for next steps here. This past summer our building got struck by lightning. Not sure how close but it took out some of our building controls. These have been addressed and it now seems I have contact with the systems on these controls. In other words they populate my screen. However I have no impact on their operation. Namely the fan control/motor contactor. I'm unable to call it on.

All the fuses are good I have power to the contactor and nothing on the other side. I have a demand but it's not pulling in. I can activate the motor by pushing the contactors in manually. My question is, are there any other steps I could take to get from very confident to sure it's the contactor.

Contrary to what some may believe, small private schools like ours, especially girls schools rarely have a money tree so the cost of this component is significant. Fortunately this AHU is redundant do to a long past lack of understanding of our steam system.

Any insight would be appreciated.

Peace

M

pecmsg · November 4

lightning strikes are covered by insurance.
beyond that get a meter and follow the electrical flow

Grallert · November 4

Thank you. Yes I forgot about insurance, Thanks for that reminder. Hopefully they'll cover the computer guys full day with parts. And yes I used a meter to follow the electric right up to the contactor. I forgot to add a picture. here it is.

Jamie Hall · November 4

If you've got power and control up to the contactor, I'm going to go out on a limb and bet that the coil got fried…

pecmsg · November 4

https://forum.heatinghelp.com/discussion/comment/1818088#Comment_1818088

X-2

Have you ohmed out the coil? Overload tripped?

ratio · November 4

Stupid question, but is the overload relay reset? After that, you can ohm out the coil to see if it has continuity (if it's open circuit, it's positively failed, but a shorted coil wouldn't be caught by that test).

Test any interposing relays, as well as the BAS output itself. Check the fuses (primary & secondary) of the control transformer (black box-thing that's just in the frame on the right).

mattmia2 · November 4

Since it also has reverse phase protection, make sure the phases didn't get swapped in some other repair. So you have to make sure if the overload could have tripped you do whatever you have to to reset it and make sure the phases are right. If that is right and you have control voltage then the contactor is bad. I think there are versions with diagnostic lights on them, i would go with that for a replacement.

I might manually operate it with an ammeter on the various phases and make sure it is within specs.

EBEBRATT-Ed · November 4

I believe the coil connections are at the top behind the 3 phase. But you have some extra wires coming off L1 & L2 where the power connects so I am guessing the coil may be the same voltage as the power either 208-240 or 480 volt.

And yes, check to see if the overload has been reset.

I think Furnas has been bought by Siemens

109A_5 · November 5

I believe the 48ASE3M20 is a manual reset. Has the white button been pushed ? Are the normally closed (NC) contacts actually closed ? If they are open that may disable the contractor's coil.

Grallert · November 5

Tested all the fuses but I have not ohmed the coil. I'll do that in the AM. The overload will not reset I tried that right away because I'm a big fan of resets.

Forgot to hit post for this. So now it's the next day and I'm second guessing. I appears I have no control over th rest of the components, The valves. I've just now sent an email to the control company who traced the original fault to see if there is something on their end.

Thank you all for the good suggestions I will update as I go along.

ratio · November 5

With regards to lightning, BAS controls are a lot more sensitive than motor starters, unfortunately.

Grallert · November 5

https://forum.heatinghelp.com/discussion/comment/1818225#Comment_1818225

Yes I'll be interested in seeing the bill for that service. I starting to think the issue is still in the BAS somewhere. We'll find out shortly.

Grallert · November 6

OK so the Issue turns out to be… wait for it: ME as far as I can tell. I had made a schedule change in the spring during a warm day cold night shoulder season spell and the fan won't run if we've reached set point or out of schedule unless I force it. Because the zone has a funtioning steam loop it's often satisficed. In fact I'm more likely to run the AHU for fan only when the hall fills with people, to take the out. Anyway because we have no cooling I don't pay much attention to the system until we get close to heating season. By then I've forgotten what I've set things to. Not always but sometimes. So new control works service was good lightning was the entail culprit and I think we're on the road.

Thank you all for the input and advice.

M

Jamie Hall · November 6

You aren't the first one to do that sort of thing!

Motor contactor

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