I can't BELIEVE I missed this one. I don't agree with the two check valves but, if air was coming out the drop pipe as it was lowered, the check valves must be facing the right direction.
One of the problems with a VFD is that you lose head by the square of the speed. So this 3450 RPM pump cannot build enough pressure to lift water from that depth until it gets up to 2700 RPM or so. If the VFD is programmed to take 20 seconds to start, then the first 15 seconds it is doing nothing, the amps are still low because it is not yet pumping water, and it shuts off thinking the well is dry. If it will run long enough to get above 2700 RPM, then it begins to pump water and the amps will increase.
Another problem with VFD is that even the people who make and sell them have no idea how they work. So try another controller is always their answer because it is a computer and there could be any number of things wrong with hardware or programming. The VFD is a computer that has a fan in it to keep the electronics cool. This makes it susceptible to lint, dust, insects, and temperature changes. It is also susceptible to power fluctuations, and can just crash for no reason as can any other computer. When this happens you are not just frustrated but, also OUT OF WATER.
Running the pump and motor with a VFD also has many side effects. The Kingbury type thrust bearing does not get any lubrication below 1800 RPM so, slowly ramping up or down below 1800 RPM shaves off part of the bearing each time. There are several critical speeds which causes destructive vibration in the pump and motor. A 230 volt VFD will send voltage spikes to the motor and wire of over 1,000 volts. This reflective wave has an accumulative effect making the voltage at the motor higher, the longer the drop wire is. Harmonics and stray voltage are fed back into the power supply and can cause things like lines on the TV and static on the radio and even cancels out some AM stations. Stray voltage can cause dairy cattle to get sick and decreases milk production so it is bound to also affect humans. Then because you lose head by the square of the speed, it is not able to be slowed down enough to save any energy. You will actually be using more power per gallon of water anytime the VFD is not running at full speed.
One of the biggest problems is that these units do not use a pressure bandwidth for on and off. If you set it a 50 PSI, it is always at 50 PSI. This means that a pressure tank of any size will not express any water. So every time you wash your tooth brush or the ice maker fills the pump must start up. This also causes a dripping faucet or forget to giggle the handle toilet to continually ramp the pump up and down until it faults out for good. There are some new VFD's out there but, VFD technology is fairly old, 30 years or so old. The Cycle Stop Valve is actually newer technology that was designed to mimic the function of a VFD without all the negative side effects, high cost, and short life span of VFD controlled equipment. I know that this 3 HP VFD system was not cheap so, I hope you can get it running. When you get used to the constant pressure but, tired of the lack of dependability, you can easily switch to a CSV for long lasting, inexpensive, dependable, constant pressure.
