Chattering in AC Relay

Chattering sound comes becuase of 3 reasons

1. Your relay coil is not getting enough voltage as per its rated capacity.

2. The electromagnet link is broken

3. there is dust or particles (dielectric) which are inhibiting the operation.

most probably, the relay's coil is not getting enough voltage. mAybe its rated voltage is 230 Vac . But you are giving less than 150 Vac. Thats why.

Dust is the main reason.

DHAYANANDHAN.S

I would suggest that you install a voltage sensitive relay that operates at -5% & +5% of the rated voltage (230 volts). This relay would ultimately control your switching contactors. If you want even further control, an AVR may be needed, providing you have enough availablility of current.

Tom,

You are assuming that the street lights are causing the low voltage problem. This may not be the case.

I live in Thailand & in the rural areas, it is quite commen to have huge voltage fluctuations for extended periods of time, none of which are generally related to the load of any particular user.

What causes this?

A combination of many possible things;

1] poor/low quality power distribution network (installation & quality of equipment).

2] wind.

3] animals.

4] excessive loading due to bad planning (bad or non-existent max demand planning).

5] car accidents.

These things are typical in most developing countries.

It is not the street lights which are causing the low voltage, it just happens to be the distribution network in this backward area. The area has no undervoltage protection and it is imperative for me to protect my street lights and hence decided to use a standard 2 pole relay which would cut off @ 110V or lower and pick-up only on more than 170V.Could not get any relay which suits the application, it would mean low pickup & very low drop-off( 30V).It blows my SMPS supplies & LEDs.The chattering is not dominant if I supply DC rectified voltage to the relay but drop off is pretty low.Used a series resistor(3 times the relay resistance) in the drop-off circuit and maintained mains voltage for pick-up. Used one of the auxiliary changeover contacts for that.

Thanks for the comments

I refer you to my previous post (post number 2).

If the "normal" supply voltage is supposed to be 230 volts, you should not be choosing relays (or other devices) that cut off at anything less than + or - 5% of the "normal" supply voltage (about 218 volts at the lowest & about 242 volts at the highest level). This will ensure long life of equipment.

At the extreme, you could go for a 10% variation but I would not exceed this limit unless you are happy to replace equipment on a regular basis.

You must have a "female" relay. They tend to chatter quite a bit but preform no actual work.

Consider using a "male" relay, it takes very little to energize its coil but after that it's unable to switch again for several hours.