Pool motor runs slowly for a couple of seconds then trips.To restart one has to wait for truflex plate to click but same result when you try again.

When you switch it on, watch the breaker trip. Does it slowly move to off? That is a lazy breaker and needs replacing. People use breakers as switches and they are not made for that, so they wear out.

If the breaker snaps straight to off, you have a short to earth. Look for water around the electrics particularly at the pump.

If you can't see anything obvious, call out a pool electrician to diagnose and fix.

There are other ideas on the link.

https://www.google.com/search?q=pentair+pool+heater+trips+breaker

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earth leakage is tripping the breaker from bad insulation or water in the motor or wires

Check for restrictions causing the pump motor to be overworked.
Motor is overheating, the the Thermal Overload Switch senses that and will trip. Once the motor cools, it will restart.

Drag on the Motor is increasing the HEAT, the HEAT is what is causing the trip. Your motor sounds like it is getting weak.

check the breaker might be weak possibly from previous pump motor also if it was hooked up incorrectly at first might have done damage to motor windings

I assume the device being tripped is a GFCI -- the pump has a short to ground. Most practical solution is to replace the pump. Don't try to run it from an un-protected outlet (no GFCI) -- it's dangerous.

Charlie

I am thinking the run capacitor is bad, if the motor has a centrifugal swith on the shaft under the motor cover, it could be sticking in the "start" position. This can be repaired with a non-conducting cleaner for the switch..

motor is locked up in the motor are two bearings they will rust if they are set up for a while.you can take the back off the motor and where the shaft goes thru the houseing take a pair of needle nose plires and try to free it up.

internal thermal over loads in motor are working properly! how old is the motor? double check all vavles on the intake and discharge line to make sure that they are open? sounds like the pump is pushing against what is known as dead head pressure. obstruction in discharge line! if valves are ok you can take the jet covers off (the piece that helps direct flow of water) which will relieve some of the pressure should allow it to run without tripping tgermal overloads. if none of this works replace motor!!