Pump, AC, Refrigerator Motor Burn

Do you have surge protectors?.

Pnaban, no I have not. I ever thought but for home application I just ignored it. So, what could be the cause of frequent damaged my equipment ?

Thanks

Please give ratings(I/W) of pump,refrigerator and AC to check whether the total is 3.5kW. If load is high there will be VD and if no OL protection is provided items will burn

2xAC @1650 W + Waterpump 175 w = 3,475 W, Sorry,I'm out of my house for a month- i can't give you spec of each equipment eg. I/HP/range volt etc. Could you please also recommend me what kind of surge surpressor to protect these ?

Thanks

You didn't mention the rating of refrigerator,voltage and capacity(amp/kVA) of power contract with the utility. The contracted supply should be at least 30A. Check with them whether your load is acceptable to them to be supplied with their existing capacity of feeder We do not know the VD in the distribution lines. If it is too low stabiliser may not help. Regarding SPD you should use one recommended for use at the incoming supply main breaker.

Can I make temperory conclusion that these equipment burned because these working undervoltage due to stabilizer (motorize type) had slow respond to recovery the voltage ?

I've read some thread in this forum regarding motor heat, motor protection..helps me better understanding about motor.

Your conclusion is correct. Replace the stabilizer with quality one and observe .

Please confirm if you had installed MCB in circuit?. What protection you have provided for overload, Short Circuit?.

Yes, Only main CB for short-circuit, sorry-I didn't remember the rate amps of MCB. No special protection such as surge protector, termal overload relay, overcurrent (ref to thread in this forum)

<...No......protection.....overcurrent.....>

That would be why the motors burn out.

You need a UPS.

The normal load might be 3.5 kW, but the starting current for each motor is several times that of normal load. If the supply V drops on starting, the stabilizer may saturate and the motors stall and burn out. UPS is normally used for electronic and control equipment. Check with your utility if they can supply 6 x rated current at 380V -10% for starting only, for each motor. Don't forget other loads, such as hot water (switch off when not home) or cooking.

Please check all the calbes whether they are hot or not. Then check the specification of electric wire installed in your facility. Then, check any connection for any loosen wire since these would contribute to the problem.

Check the frequency of voltage drop then you will switch off some loads to be operated at predetermined time avoiding the worst voltage drop. If the voltage drops too much so the pump is impossible to start, then it overloads and burns.

After you ensure things are in good condition. Then, 20amp stabilizer seems not enough for those load because you may certainly have lighting, and other loads. You should increase it to 40amp.

If the voltage drop is permanent. Then, the UPS or stabilizer are recommended. If the voltage frequently is fluctuated. This will also reduce the life of these equipments.

I have once faced this problem when installing the temporary power system for the contruction site. (Cable cross section was not enough, connection was loosen, terminal burned, wiring distance was too far... that caused the voltage drop). The worst case is we have the total black-out over the site. (AC burned, motor burned, photocopier burned, lamps burned).