Relay race solutions?

[Doghandler]

At the moment we have a little bit of a problem on one of our machines.

We have a shunt coil on the main power breaker on the machine which is tripping every time we reset the power to the machine.

The coil is powered up from a contact on a 24V DC emergency stop relay. Currently we have placed a timer in series with the contact to give a delay and this then gives the contac enough time to close and the shunt coil does not trip the breaker.

Having a delay is not desirable and we first thought that making the emergency realy 110V (same as the shunt) that it would remove the delay. It does not.

So now we are at the point of making the delay a small as possible while still being cost effective. Thus we have come to the point of putting a cap in series with the shunt to effectively become our timer. 1000uF cap gives a delay of about 0.1 secs. This hasnt been tested yet...

Hs anyone else had these problems or a similiar one and found a solution that works. Any other ideas would be most usefull. Thanks

 

[ourious78]

Try putting a thermistor on the A/C line incoming to the equipment. Sounds like the initial power surge coming in is doing you in. You could save some money if the power to the relay power (AC/DC) is less in voltage and watts by putting the thermistor there instead of trying to find a high power thermistor.