Pool Pump Winding Burnt Out – Why When It Has A Protector?

[Phil_ne_uk]

I’m hoping some of you knowledgeable guys can help with a question I have please.

My swimming pool pump wasn’t on when it should have been so I checked the control panel and found that the overload light was on. I understand this to be similar to a basic fuse in a plug which stops the appliance buggering up?

I got the pool company who built the pool 5 years ago to come and look at it and they said the windings had burnt out.

However I read this on the Hayward website...

Motor Shuts OFF – Check For:

1. Low voltage at motor or power drop (frequently caused by undersized wiring or extension cord use).

Solution: Contact qualified professional to check that the wiring gauge is heavy enough.

NOTE - Your Hayward pump motor is equipped with an “automatic thermal overload protector.” The motor will automatically shut off if power supply drops before heat damage can build up causing windings to burn out. The “thermal overload protector” will allow the motor to automatically restart once the motor has cooled. It will continue to cut On/Off until the problem is corrected. Be sure to correct cause of overheating.

So surely this facility should have prevented the windings from burning out, correct?

Thanks, Phil

[Naam]

So surely this facility should have prevented the windings from burning out, correct?

normally yes, but even thermal protectors can fail when material fatigue sets in because they were triggered too often during a short period of time.

[Phil_ne_uk]

So surely this facility should have prevented the windings from burning out, correct?

normally yes, but even thermal protectors can fail when material fatigue sets in because they were triggered too often during a short period of time.

Thanks for your reply Naam.

You say because they were triggered too often during a short period of time.

This is the first time this has actually happened. That’s why I thought the protector would prevent damage.

[Khun Jean]

They have to be tested form time to time to. At least once every month. I don't know how easy it is to test in your setup.

[Naam]

So surely this facility should have prevented the windings from burning out, correct?

normally yes, but even thermal protectors can fail when material fatigue sets in because they were triggered too often during a short period of time.

Thanks for your reply Naam.

You say because they were triggered too often during a short period of time.

This is the first time this has actually happened. That’s why I thought the protector would prevent damage.

my "triggered too often during a short period of time" can also mean "triggered too often within 30 minutes or even less". most thermal protectors are tiny relays with a moving contact. under certain conditions (even within a few minutes) an arc can build up which burns that contact and causes the relay to fail.

[Phil_ne_uk]

Thanks for your replies. The protector has never been tested as far as I know as I knew nothing of this until just a few days ago.

Namm, it sounds like you’re saying even the protector can fail which certainly seems to be the case. So I guess it’s a case of it just wearing out as stuff does.

Incidentally home & pool are charging me 3300 baht for new bearings and a new impeller and 2800 baht for new windings. Including fitting. Do these prices sound about right?

Thanks, Phil

[Mudcrab]

Thanks for your replies. The protector has never been tested as far as I know as I knew nothing of this until just a few days ago.

Namm, it sounds like you’re saying even the protector can fail which certainly seems to be the case. So I guess it’s a case of it just wearing out as stuff does.

Incidentally home & pool are charging me 3300 baht for new bearings and a new impeller and 2800 baht for new windings. Including fitting. Do these prices sound about right?

Thanks, Phil

Hi Phil,

no idea about the costs of repairs as this will depend on the size of the .Heat kills motors (winding anyway). I suggest you check both the pool filter and motor fan for dirt build up regularly in the future...when a motor slows down (due to crap in the impeller body and so an increase in load) the motor current increases along with a reduction in the cooling effect of the motor fan and leads to heat build up in the motor. The motor protector, or overload simply works on motor current...this is quite different to heat build up in the motor due to the lack of cooling. Multiple starts of a motor can lead to overheating of the windings even when the current is still within the design pararmeters of the motor.

In other word the motor protector is a "dumb" device. These days there are some "smart" overloads that can compute motor temperature based on the time/current characteristic or the motor circuit and can compute the temperature of the motor winding and offer much greater protection.

Hope this helps

Kevin

[Naam]

Thanks for your replies. The protector has never been tested as far as I know as I knew nothing of this until just a few days ago.

Namm, it sounds like you’re saying even the protector can fail which certainly seems to be the case. So I guess it’s a case of it just wearing out as stuff does.

Incidentally home & pool are charging me 3300 baht for new bearings and a new impeller and 2800 baht for new windings. Including fitting. Do these prices sound about right?

Thanks, Phil

repair price quite fair, especially for a "Hayward".

[Valentine]

Thanks for your replies. The protector has never been tested as far as I know as I knew nothing of this until just a few days ago.

Namm, it sounds like you’re saying even the protector can fail which certainly seems to be the case. So I guess it’s a case of it just wearing out as stuff does.

Incidentally home & pool are charging me 3300 baht for new bearings and a new impeller and 2800 baht for new windings. Including fitting. Do these prices sound about right?

Thanks, Phil

It could be that water got through to the motor which caused it to burn out. Noisy bearings are a sure sign of serious trouble coming if not taken care of quickly especially if you notice a little water leaking out under the pump which means the mechanical seal is failing.

[PoolDoctor]

It could also this: on most control panels, there is an overload trip installed onto the bottom of the magnetic switch. If it is set too low, it will trip the system, and cause the overload to come on. Just turn the dial to the right a bit, and should solve this. As pumps get older, they draw more current (like getitng out of bed in the morning) which causes really sensitive overload settings to trip. Most pumps run at about 14amps if I am not wrong.

You will know if the bearings are gone by the way, together with your neighbors! If it isn't a sound like that, the bearings have little to do with it.

Thermal overload though, is different. A thermal overload in the pump will shut off the pump, but will not trip the overload switch in the panel. A pump runs hot (and trips the thermal shut off internal to the pump) when there is insufficient water coming into the pump.

Gil