My 61454 keeps tripping the overload protector?

by Chris H
(New York)

I have a 5 year old central pneumatic 21gal compressor model 61454 that keeps tripping the overload protector.

When I turn the unit on it runs for ~15 seconds then trips the overload.

Central Pneumatic 61454 air compressor
Central Pneumatic 61454 air compressor

If you hit the reset button the unit will run for ~5 seconds then trip the overload again, which you can keep repeating.

If you let it sit for 1 minute you can reset the unit will run for ~15 seconds again.

The unit is in great shape and hasn’t been used that much.

The unit is on its own circuit which it has been on for the last 5 years.

After reading some different complaints about the unit I replaced the oil with fresh synthetic compressor oil which did nothing.

Seeing that people complain about the capacitors going bad on them I checked mine. The unit has 1 capacitor, it has a few minor dents on it, but it appears to be functional (builds resistance when hooked to a multi-meter).

Any thoughts what the problem could be?

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Could it be overcurrent?
by: Doug in s.d.ca

A couple of thoughts –

Is the filter reasonably clean?

Otherwise, sounds like a motor failure, or the overload protector is broken/weak.

Ideally, check the current with a clamp-on meter or something like a “kill-a-watt” meter. Should be 13-14 Amps. If that’s the case, and it blows, then the protector is bad.

If it’s much over 15A, then you may have a motor problem, and hope it’s the cap. When they lose capacitance, that can cause this, even though it’s not “clearly bad” as in open or shorted.

Let us know how you make out, please.

Good luck.

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More info
by: Chris H

Thanks for the suggestions Doug.

I checked the filter and it looks clean.

I then picked up a clamp meter and tested the unit. The number fluctuates a lot…but it seems to be running about ~16.6 amps on the hot lead, ~15 on the neutral and ~1.6 on the ground…then pops the overload…

So it seems, like you said, its a motor problem.

Is there other way to test the capacitor other then measuring the resistance like i did? If it is just the capacitor any suggestions where i could purchase one for the unit…some people online say its a hard one to find and that harbor freight is no help…i even saw people talking about combining 2 smaller capacitors to get the correct capacitance of the one on the unit.

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Where to get capacitor
by: Bill

Any capacitor that has the same microfarad rating ( µF ), and the same voltage, should work, as long as you can get it to fit the footprint.

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More on overload
by: Doug in s.d.ca

Chris:

ALL of your current from the hot side should be going thru the neutral, and ground should be zero.
\An electrically leaky cap might cause that.

If you have a GFCI breaker on it, it should trip, but I’m guessing you don’t.

Some multi-meters have a capacitance range, but they may not be able to accurately read large caps, so if you decide to buy, check that it goes high enough. Google “capacitance meter” and you’ll find a few, along with a good explanation of how it works from Fluke.t

The manual doesn’t seem to have the value(s) the cap. What is it? Maybe I can help with that.

And yes, unfortunately HFT is not very good about spares, like most sellers. Sadly, it’s just not economical to do so.

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More info
by: Chris H

Thanks again Doug and Bill,
You are correct about the unit not being on a GFCI breaker…should it be?…Turns out that the clamp meter I picked up can do capacitance. I tried testing the capacitor, but it overloads the meter….i checked manual for the meter and it can’t measure past 100uF or the capacitor is bad. After seeing that i can’t measure the capacitor with my meter i tried testing it again with resistance….this time i get no resistance at all…Could the capacitor have fully failed when i played with the unit trying to measure the amps?

The capacitor specks are as follows
Huizhong CBB65A
130uF +/- 5% SH
250VAC 50/60Hz
40/85/21 CP
Internally Protected
10000AFC PB1300

on Amazon I see capacitors with
108-103uF 250V
130-156uF 250V
would either of these work…or do i need to be more exact with the 130?
Thanks again for your help

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GFCI and Capacitor
by: Doug in s.d.ca

I mentioned the GFCI because if there were one, it’s failed. Not having one is OK, but a while back the NEC started requiring them on all 120V circuits, even lights. They used to require them only on circuits subject to dampness, like laundry, kitchen and bath rooms.

Anyway, capacitor:
Given the value, (130mfd or 130μ), and voltage, it would be a start cap. That being the case, it’s not critical, so I’d go with the cheaper one, as long as 130μ is in its range.
I suspect that the cap that’s failed was available cheap, and the +/-5% is overkill. If it were a run cap, then it’s more critical because it’s in the circuit all the time.

You might consider getting one of each, as it’s possible that the reason this one failed is that the centrifugal switch in the motor is also failed (not opening), which will cause the new cap to fail, sooner or later.

HTH, and good luck.

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It’s not the capacitor
by: Chris H

Doug,
Sorry it took a while to respond.
I ordered a new 108-130uF starting capacitor and swapped out the old one. Unfortunately my compressor is still having the same issue of running for 15 seconds then tripping the overload. The unit is still reading in the high 16 amps and I am still getting an amperage read on the ground with the new capacitor. I assume that probably means the motor is shot and I should consider replacing it or the whole unit.

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Not an overload issue
by: Anonymous

if your compressor starts up then shortly trips the built in breaker, it has nothing to do with the electrical system.

Simply look on the head of the motor, you will see a screw in valve with a nipple on it. seems to be a compression release to prevent hydro locking. Unscrew it and turn on compressor. it will leak out from here. however, if it keeps running without shut down, there is your problem. I have the same model and as of this day cannot seem to find a replacement part for it. just adding my 2 cents in. thanks.

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About not an overload issue by: Anonymous
by: Doug in s.d.ca

I beg to differ.

It appears you refer to part 3 in the parts list.
It is called out as “start valve”.

That’s actually an engineered leak to relieve pressure on the pump head when it stops. It is an inefficient substitute for an unloader.

In case you are not referring to item 3, say which it is.

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Central pneumatic bogging down
by: Anonymous

Two things here , I have worked on industrial air compressors for 12 years. If it bogs down and trips the breaker it’s more than likely the check valve on the tank not the start valve. Or your capacitor is going out and bogging the motor down. The pressure switch relieves the head pressure on shut down not the start valve.