I have installed submersible pump 170 ft deep well for my bilding to store water in the overhead Tank (40 ft) . It was working well for the last 4 years . Now it works well i.e with desired pressure if the voltage is above 250 volts and it takes 7 amp current . However, if the voltage is below 230 volts , the pump keeps running but the water is not pumped up (the current when no water becomes 5 Amp) . I have tried to change the capacitor(36 UF 440 volts) but no effect . Is there any problem in the control panel or the pump .
Thanks

TK, I kicked this up to you in hopes you could had more information the we did. Can you help this OP? Speedball1

I'm not following this one. How is it that the voltage keeps varying so much? Where are you located?

I'm not following this one. How is it that the voltage keeps varying so much? Where are you located?

Well, I am in Delhi and the voltage vary between 230 to 250 during the day

It is not logical that as the voltage drops the amperage also drops. Also the pump motor should be able to tolerate a 10% voltage fluctuation.
As the voltage supplied is reduced, the amperage draw of the motor should increase. If the motor used 7 amps at 250 that is 1750 watts. At 230 volts the amps should 7.9 amps.

How far is the well head from the point where you are measuring voltage and what size wire is being used?

Pm, I am guessing some on this, but is it possible that the electricity demand in your area has increased but the capacity of the grid has not? That would, I guess, mean a drop in availlable power during those times and result in your pump not working well. You might try only running the pump during evening/night hours when there is less demand for power in the neighborhood. Again, just speculation... a "swag".

Need to know the exact specifications of the pump motor, what voltage is it rated at at what are the tolerances it will operate properly for a well that deep.

HK is correct that most motors will operate +/- 10%. If it is rated at 250 volts, then minus 10% is 225 volts. However, while it may still run at 225 volts, the speed and horsepower has been reduced also.

I don't know much about well pumps, but I do know that a motor 170 foot deep has a great deal of weight to overcome to force the water up that distance, and reducing the speed and horsepower will; affect the operation of the motor trying to push the water.

Over time, motors get weaker from age, fatigue, and operating under low voltages conditions.

The Highs and Lows of Motor Voltage (http://ecmweb.com/design_engineering/electric_highs_lows_motor/)

I believe the motor has been damaged by the low voltage condition over time.

May need to change the motor for a new one , hopefully one with tolerances that match the voltages you have.

You may need to look into something that will regulate the changing voltage to prevent damage to a new motor.

It is a bit complex situation. First we have to have certain things to come to a diagnosis.

1. the water conditions in the borehole. What is the water level? Pumping and static.
2. the parameters against which the pump+motor was procured. i.e the head and flow rates of the pump as well. It will be given on the pump+motor plates.

What I assume that the water level in the borehole has decreased and specially at the day time when all the surronding pumps are working the lower water level doesnot allow the pump to reach it at your desired level. It is not due to voltage because voltage doesn't impact on the speed of motor. However, when there is lesser usage in the surronding the waterlevel in the borehole would increase and the pump might pump it out at your desired level.

If you don't want to change the pump just do one thing. Put a Valve at ground level instead of 40 ft height and you will start getting the water. Just try...