Motor Reset "Pops" on Cat 3535 pump

[Rudy]

My manager found the motor reset "popped" on my motor that drives my Cat 3535 pump. I think it's a 25 HP motor (or so), and the whole setup is 15 years old. I haven't done (or needed to do) a single thing electrically to my setup ever.

What would cause the "reset" to pop? Is the contactor going bad, or perhaps the motor going bad? Ideas?

 

[robblackburn]

I had the same thing recently and it wash the motor contactor. May also want to check the breaker. Hopefully that is the only problem.

 

[RykoPro]

My manager found the motor reset "popped" on my motor that drives my Cat 3535 pump. I think it's a 25 HP motor (or so), and the whole setup is 15 years old. I haven't done (or needed to do) a single thing electrically to my setup ever.

What would cause the "reset" to pop? Is the contactor going bad, or perhaps the motor going bad? Ideas?

The only way to know is to measure the current draw (amps) when the motor is running under load.

 

[MEP001]

Unfortunately an amp meter is expensive - you can get a clamp-on inductive one at Harbor Freight pretty cheap that will do the job. As RykoPro said, you'll need to measure the current draw of each leg and make sure it's not exceeding the motor rating, and you might also double-check the thermal overload to see that it's set to the same amperage as the motor rating.

Keep in mind also that ambient heat can affect the thermal overload, both in increased drag on the motor parts from expansion and the extra stress on the electrical parts that make it work.

 

[Jim Caudill]

I'm assuming we are talking about the overload trip on the motor starter. Almost everytime I have encountered this at my wash, it has been due to burned contacts. I upgraded my SS contactors to the next size. On these big contactors, I disassembled the contacts and filed them a bit. You can buy refinished contacts a whole lot cheaper than you can buy new ones. My contacts can be bought refurbished from Aaron Iron & Steel 1-888-293-6004 for $41.50 per pair. There may be as many as 6 pair in your contactor. No, this stuff ain't cheap. Make sure you are comfortable around industrial electricity before you go putting your life on the line. my starter is made by "Furnas" and is for something like 100 amps. Do an internet search for "Furnas 14HSt32A* size 3" the part number for replacement contacts is: 90 amp contact kit 75HF14 series A E5P 100

 

[Rudy]

Yup....I found the contactor contacts dirty and pitted. When I went to the Grainger catalog to price out a set of Square D contacts....$570!!!! I filed them lightly, used some emory paper...and reinstalled. The motor now runs fine, but I'm wondering how long before my "dressing" up the contacts will last.

Thanks...I'll check the internet for "refurbished" contacts. It sounds like it would be a good idea to get a spare set on hand.

 

[mac]

On older pumps, over 5-7 years, it usually is the contactor points. A little detective work will find you the new contact points. Two other common things that cause this: first is loose connections. Check EVERY connection starting at the breaker panel, then auto panel, contactor and overload, and finally on the motor itself. The other most common thing is a slow opening solenoid. Most everyone has the pump and solenoid coming on at the same time. If the solenoid hesitates just a tiny bit, the pump pressure will keep it from opening and the resulting pump hemmoraging will trip the overload. I like to delay the pump starter about a second to prevent this.

 

[Rudy]

The overload tripped again this morning. The contacts that I cleaned two days ago are covered in carbon. I found a local supplier that has aftermarket contacts for $150...so I'm going to give those a shot first. I'm also wondering if a weak coil could cause my problems??? It appears to be working reliably, and I don't hear any chattering...although that's hard to tell with a 3535 pump pumping eh?

Is it likely the overload shunts fail?

 

[Washmee]

The overload tripped again this morning. The contacts that I cleaned two days ago are covered in carbon. I found a local supplier that has aftermarket contacts for $150...so I'm going to give those a shot first. I'm also wondering if a weak coil could cause my problems??? It appears to be working reliably, and I don't hear any chattering...although that's hard to tell with a 3535 pump pumping eh?

Is it likely the overload shunts fail?

Not likely. Get a clamp on meter and check the current draw. Until then all you are doing is guessing.

http://www.sears.com/shc/s/p_10153_...hop&sName=Multi-Meters,+Testers+&+Accessories

 

[Rudy]

The amp draw on all three legs was basically even at 51 amps. This is for a 25HP motor. Whatever is going on is intermittent...ie contacts.

 

[Jim Caudill]

My initial thoughts are that after you "refinished" the contact surface, you left them contaminated. There's a reason they make "contact cleaner". Also, depending on how you "refinished" them, you could have embedded some type of abrasive in the contacts. They also make special "burnishing files" for dressing copper contacts. Long-winded way of saying that you might be on the right track, but there's more to it than meets the eye. If it were absolutely foolproof, there would be no aftermarket business reconditioning them.

 

[Rudy]

The Aaron Iron & Steel recommendation was a good one. It turns out they were only 1/2 hour from my house, and I took the whole contactor to them. BTW....this forum is awesome for such things.

Anyway, it turns out that they usually look to see how much silver is left on the contacts. Mine were OK, but not great....so I picked up a replacement set anyway at a really fair price.

I'm beginning to think (as suggested) that I have a slow opening undercarriage solenoid. The pump may be trying to pump into a locked manifold....and the overload trips.

These intermittent issues can drive one crazy eh? Again, thanks for the many suggestions. They are invaluable.

 

[RykoPro]

If the solenoid is "slow" you should see this with your amp meter. Realize there will already be an "in-rush" current spike on the start-up of the motor.
You may have a contactor coil problem or even an alignment problem with the points when the coil pulls. We normally replace contactors rather than rebuild them, especially with a 25 HP motor. Its not worth the risk of ruining the motor with a bad contactor.