Using TVS Diode P6KE across relay coil but then also relay coil is getting damaged.

Its not local, its costly.Its from reputed manufacturer.

My thinking is that due to Contact it is getting damaged.

If the coil is being energised by the alternator without any dc rectification then yep it'll generate a lot more heat and fail more rapidly

We are trying to help....

If you can't provide a circuit then I'm afraid my anwers are limited to guessing ...

Mark

Coil is energized through Battery 24V.

Circuit connection given above.

Just directly connect one starter switch at one point .

The starter switch is connected to batter +ve.

Is the load powered directly from the same +ve too? Is there anything on the load inductor wise that could cause a huge back surge when it's switched off, something like that could force through the coil to the ground connection damaging it as it goes

Actually Here load is motor ,battery is connected to This relay and engine.Relay contacts are used to connect alternator output to motors. through wires

Currently i had gone with 40V diode ,it is not able to prevent the damage

cn i reduce the volatge to 30V

I'm with lucie tozer.  I think you've got a heating problem caused by peaks in the alternator output.

You say the relay operates 3 hours with no load, but was that on a lab supply, or on the alternator?

Stick a scope on there and have a look at the coil volts.  I can't think of a way the load could directly damage the coil.

Once you know what the waveform looks like, you can send it to the manufacturer for help.

A charged battery will be around 28V (you have a battery in circuit?), or a bit more, so a 30V diode may be a bit tight.

Hi Amol,

My experience with situations like this indicate that the coil is getting too much current during energization. mcb1 is right in his assesment. Each time this over current occurs the wire that you show in the photo "heats up" as it is exposed in the air and the weakest link. The repeated heating of the wire causes it to change its temper and resistance and become more and more susceptible to failure. I would put a low resistance, perhaps 5 ohms, in series with the the circuit that feeds the coil. If the coil won't pull in with 5 ohms try 3 ohms. This will limit the energizing current and should prevent the failure you are seeing.

John

Hi Amol,

I thought of one other possibility for the cause of this problem. If for some reason the solenoid relay coil is not properly secured to the armature it will move during the actuation. This can cause a mechanical stress or a bending of the leads. Just like bending a wire back and forth will break it, repeated actuation with a loose coil will also break the leads.

John