water pump

[EDY]

Hi
I recently purcahsed a 1.2KW water pump and when ever it turns on light blink. now I know I should connect a capacitor to it but how and which?

cheers

[hotwaterwizard]

Use bigger wire going to the pump.
Too Small of size wire causes a line Voltage drop and the Motor will draw too much Current .

[audioguru]

Use bigger wire going to your house, farm or castle.
When the motor is turned-on, it will draw many, many amps of current until it is up to speed. A capacitor won't help much unless it is huge and expensive. A high-voltage, high-value capacitor wired in parallel with the motor will lower the power-factor of that big inductance, reducing its power-draw and your electricity-bill a bit.
The voltage is dropping along the weakest wire between the power generating station, and the point where the wires to the pump and your lights join.

[hotwaterwizard]

I said The same thing only shorter.LOL

[audioguru]

Hotwaterwizard,
Sorry. No, you didn't say the same thing.
Using bigger wires going to the pump will not reduce the voltage-drop along the wires going to his castle. The light will still blink when the pump turns on.
But I see your point that the motor will draw more current when fed a reduced voltage from smaller wires. Won't the increase in current be cancelled by the wire resistance that will limit that current?

[EDY]

audioguru is right, but tnx to you both. cables in my home are all ready pretty big. i meen they are standart power cables that are used for electronic instalationas and I think ther are preety much capapble of providing much more current and voltage than my pump needs. but can you give me some standard values of those capacitors. I know they are expensive but I have to fix this. it is anoying me. cheers ;D 8)

[audioguru]

EDY,
Your problem is not the cables in your home, it is the cables or connections that FEED your home. The light-blink may be the 1st symptom of many more problems to come if those cables or connections are bad. The undergound wiring for my neighbourhood had to be replaced because it became unreliable.
If you want to procede with adding a capacitor to your motor, you will be working on the mains, so be careful.
A good link about power factor correction is here:
http://www.lmphotonics.com/pwrfact.htm
They say that tables cannot be used since motors vary very much. So contact your pump and motor manufacturers and ask for their recommended capacitor for power factor correction.
The link above also says to put the capacitor on its own pole of the relay, since if it is still connected to the motor when the power is cut-off then it will resonate with the motor's inductance and create huge currents and damage.
Good luck and please let us know about your results.