Franklin Monodrive short cycling

[timbenson76]

Hello,
I recently purchased a home on a well with a Franklin Monodrive installed. The well circuit is 240V single phase and the well pump is a 3 wire pump. When running, the drive cycles the well pump on and off about every second, no matter the demand. I have checked the pressure tank, it says 4.4 gal, it doesn't seem to be waterlogged and is set at 35psi which is what the manual calls for at 50psi water pressure. The drive is set for a 3/4 hp well but I cannot confirm the pump hp. If it is a 1/2hp well, could this setting affect cycling, or should I be looking at the pressure tank or even the pressure sensor as my problem?

 

[Valveman]

The Monodrive with the switch instead of a transducer normally cycles about 45 times a minute. That is just the way the switch works. But it shouldn't be going completely off, it should just ramp down to half speed 45 times a minute. If it is going completely off, I am guessing the electronics in the drive are bad, which is a common problem with an variable speed type pump or VFD. Even if you pump the well dry it should take a few minutes, not just a second. But then it should stay off for a period of time. At least it is a monodrive with the single phase motor, not the subdrive with the three phase motor. Since it is a normal single phase motor you can just get a regular 1.5HP control box and do away with the monodrive. Adding a Cycle Stop Valve before the pressure tank will give you stronger constant pressure than a drive. I say 1.5HP control box because usually if they are set up to run a 3/4HP pump end, they use a 1.5 HP motor and speed up the 3/4 pump to 4700 RPM where is does the same as a 1.5HP at the normal 3450 RPM.