gsmith2853
New member
- Location
- Downers Grove IL
I have a immersible pump with a new 480v contactor that chatters on startup what could be the cause ?
480 v contactor chattering at start up ?
- Thread starter gsmith2853
- Start date
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What is the rating of the pump motor?
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
A game of 20 questions!
1. Mechanically held or electrically held?
1. Mechanically held or electrically held?
Saturn_Europa
Senior Member
- Location
- Fishing Industry
- Occupation
- Electrician Limited License NC, QMED Electrician
What's the control circuit that energizes the contactor?
Check for loose wires and make sure your nuetral is good.
I've seen miss wired control circuits cause chatter but it's usually something simple.
Check for loose wires and make sure your nuetral is good.
I've seen miss wired control circuits cause chatter but it's usually something simple.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I'll jump over about 5 questions and get to my guess.
Under sized circuit to the pump, so turning on the pump makes the voltage drop more than 20%, that makes the contactor coil drop out, which alleviates the load, which allows the the voltage to rise again, which allows the contactor to close again, which brings in the motor, which drops the voltage again, repeat ad nauseum until the coil burns out, the contacts weld, the motor fries, or any combination of the above.
Do I win?
Under sized circuit to the pump, so turning on the pump makes the voltage drop more than 20%, that makes the contactor coil drop out, which alleviates the load, which allows the the voltage to rise again, which allows the contactor to close again, which brings in the motor, which drops the voltage again, repeat ad nauseum until the coil burns out, the contacts weld, the motor fries, or any combination of the above.
Do I win?
See post #2
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Brevity is the soul of wit.Yes, but the way Jraef wrote it up was way more entertaining!
Those are my thoughts. To start with, where is the coil getting its control voltage from? It may have a 480v coil or likely a 120v coil using a 480-120v CPT. In either event the 480 is probably sourced from a 480v L-L which supplies the starter. You may be experiencing a voltage drop which affects the starter coil by causing it to not be pulling firmly. That is the first place tI would start.
ptonsparky
Tom
- Occupation
- EC - retired
A pressure switch that's bouncing around can cause some grief. Bugs or plain wore out.
Good point. I had a customer that complained about burnt or welded contscts. It was for a compressor starter on an ammonia refrigeration chiller. I asked him to check the circuit and he discovered a minor ammonia leak at a pressure switch had corroded the contacts causing contacts to bounce.
This is where thinking outside the box and plain old experience pays off.
I hope so, I like it. :happyyes:
Hence
That's why I asked for the rating in post #2 - but the OP seems to have done a runner...........
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If it only chatters on startup, I'm in the crowd that says too much voltage drop. Once motor has accelerated current will drop and voltage will rise to an acceptable level - so it runs just fine, there is just too much drop during starting.
Yes, I agree. That could explain it. But what if was say, a 2.2kW (3hp) motor on a stiff supply?
Chattering happens in manual type contactors also.
During chattering the contactor does not drop out. Otherwise the pump would have stopped. During chattering the current continues to flow and pump motor picks up speed.
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