Contactors & Relays

[scubasimon]

Hi

We have recently installed a PV system that needs to be switched when a generator starts. The generator control panel has a VFC (240V/5A) we can use to signal the contactor. There is a 150m run to the PV supply I need to isolate. I was planning to use a 40A contactor to isolate, however this is where I am a bit sketchy as its a long time since I've done anything like this. I have been told I need to use a relay as the VFC is 5A max. Can someone please help and explain what I need and how to wire this. Thanks.

 

[Knobhead]

I assume the contactor is to kill the PV supply.

It would help if you had stated the control voltage

The inrush current of a contactor coil of that size will be well below 5A. Therefore an interface relay may not be necessary. The coil voltage used is important in this matter.

Please in future, give as much detail as possible. A sketch would help as it makes life so much easier.

 

[telectrix]

here's a sketch, just for you, tony:

Monty Python - What have the romans ever done for us - YouTube

 

[scubasimon]

I assume the contactor is to kill the PV supply.

It would help if you had stated the control voltage

The inrush current of a contactor coil of that size will be well below 5A. Therefore an interface relay may not be necessary. The coil voltage used is important in this matter.

Please in future, give as much detail as possible. A sketch would help as it makes life so much easier.

Thanks Tony
Ive attached a sketch of what I think is right. My main questions are :

1. Is this ok to wire like this or do I need a relay of sorts for the feed over to the VFC?
2. Will a 2.5 T&E cable be ok for the 190m run?

Thanks again for your help!

 

[Knobhead]

Use a 24V AC octal base relay and a 15VA 230/24V transformer. Switch the contactor via the relay. I would include a fuse for the transformer.

The relay is usually only about 5VA but the transformer will give a bit of leeway when things get altered (as they invariably do.)