A Makita pressure pump that is coming off a feeder tank supplies water to

my home.

Everything works perfectly until EGAT in their infinite wisdom decide to

reduce the mains power whereby only fluorescent lights work and the

ceiling fans barely go round.

I don't know if this is a brown out, but when my girl friend goes to the

toilet, frequently at the moment at nightWater pressure due to her pregnancy, the pump naturally

tries to kick in to make up for lost pressure.

The current is just enough to start it but not enough to drive the pump,

seemingly there's a cut out on the pump that's burnt out now for the

second time.

Various Thai solutions have been suggested, externally in the pump room

and internally beside the the switch box in the house, both were

unrealistically expensive.

Something that switches off the power to the pump in the current falls

below a certain point, however will automatically go on again if the

current rises to the required level.

Thoughts of what is required, where I can purchase it, and who might be

able to install it would be greatly appreciated.

I don't know how electrically minded you are but and easy way would be to a make a circuit that would only go on if there is a certain minimum Voltage.

A Voltage divider circuit on the 220V might do this, rectify the AC with a full wave rectifier to some(adjusted to the zener) Voltage but DC now. Adjust the resistors to give you a threshold of 10% below 220V(a typically variation) when rectified to DC this would give you some DC voltage, Again you have to play around to find the right combination of resistors in your voltage divider network to match your Zener diode. Buy as zener diode that will only conduct if it has this specific voltage.

From WIKI:For example, a diode with a Zener breakdown voltage of 32 V will exhibit a voltage drop of 32 V if reverse bias voltage applied across it is more than its Zener voltage.

You could use this to turn on the coil to a SPDT or SPST relay. The relay controls the AC power to the water pump. If the voltage is high enough it turns the relay on if not the relay shuts off. If the voltage comes back the relay goes back on again.

You can find the parts at in the BanMore shops in Bangkok, near chinatown.

BTW: the low voltage in a brown out is bad for any motor including refrigerators. I happens all the time even in Bangkok.

Jerry

If you are handy with a soldering iron have a look here http://www.electronic-circuits-diagrams.co...pliesckt5.shtml no need to include the 555 and music chip.

I would go down to MEA or PEA & raise hel_l for them to get proper voltage to your house. It's their job.

After a lot of humming and hawing I finally bit the bullet, with the installation of the attached photographs.

11,000 Baht for the parts, and 3,000 Baht for the installation.

An expensive solution for a situation that rarely occurs, but the good news is that this cut out should also extend the life of my fridges and air conditioning units.