Contactor/relay.

[Skys]

Hi is there any relays or contactors that will pull in with 0v. Just continuity. Need a pump to come on but the trigger gives no volts just continuity. This is what I am been told?

 

[mainline]

Hi is there any relays or contactors that will pull in with 0v. Just continuity. Need a pump to come on but the trigger gives no volts just continuity. This is what I am been told?

Do you mean 0 volt switching ?

Can you show what the trigger is derived from ?

 

[Skys]

Do you mean 0 volt switching ?

Can you show what the trigger is derived from ?

Hi. The pump is fed from a fused spur the feed needs to run through a contactor or relay which needs to be switched/ triggered through 0v just continuity which is given when a unit to help heat a swimming pool turns on. That’s the only information I have been given. Thanks

 

[James]

Check the voltage rating of the 0v switching (relay) you may be able to use 230v through it to an external contactor of the same voltage rating.

 

[Skys]

Check the voltage rating of the 0v switching (relay) you may be able to use 230v through it to an external contactor of the same voltage rating.

Hi. All I am getting is a 2 core cable which gives me continuity when the unit fires up. This is given by the firm installing the unit. They said i need a volt free contactor.

 

[mainline]

Hi. All I am getting is a 2 core cable which gives me continuity when the unit fires up. This is given by the firm installing the unit. They said i need a volt free contactor.

I think you mean a volt free contact.

Rather than a volt free contactor.

What is this unit ? Have you a make /model

 

[Skys]

I think you mean a volt free contact.

Rather than a volt free contactor.

What is this unit ? Have you a make /model

No not been to site. Just had information passed on. The guys installing the unit have passed this information on. Basically I need to make and break a 230v supply when they give me continuity and take it away on a 2 core flex

 

[mainline]

No not been to site. Just had information passed on. The guys installing the unit have passed this information on. Basically I need to make and break a 230v supply when they give me continuity and take it away on a 2 core flex

A 2 pole 230v contactor with a suitable enclosure to house the contactor and the mcbs./rcbo ?

But without knowing the current ratings of what's needed to be switched and that the volt free switching is indeed volt free etc, then it's all going to be guesswork.

 

[Skys]

A 2 pole 230v contactor with a suitable enclosure to house the contactor and the mcbs./rcbo ?

But without knowing the current ratings of what's needed to be switched and that the volt free switching is indeed volt free etc, then it's all going to be guesswork.

The fuse spur is in place 16amp rcbo. The pump is less than 3 amps just to help the water flow. The pump only needs to come on when the unit turns on. When the unit turns on it closes the 2 core cable no volts so I was thinking feed to top of contactor from fused spur out of bottom to pump then a1 and a2 volt free if possible is triggered by the unit turning on shutting contactor. When unit shuts off lose continuity on 2 core opening contactor shutting pump.

 

[Simon47]

Simple version: feed from pump supply, via the volt free contacts provided, possibly via overload unit contacts, to the relay/contactor coil, other side of coil to neutral of pump supply. Use contacts of relay to switch the pump.
Fuller version:
You need to know the switching capacity of the provided switch and the cable. It's hard to imagine it won't cope with tbe coil current, but you may be wanting to provide separate fusing down for that circuit (i.e. from supply, via fuse to switch ...)
It might be that if the switch is suitably rated then you could dispense with the relay. However, unless the switch is a common type and easy to replace, it might be better to play safe as starting motors (even a small pump) is tough on switches and you don't want to be coming back next year asking how to replace the unobtanium brand switch in a sealed unit ...

 

[Avo Mk8]

It's been said several times already, but I can't emphasize enough that you need to find out what the rating (ie voltage and current) is for the volt free switch contacts. Preferably for both a resistive load and an inductive load.
The information ought to be in the manual for the equipment that has the contacts in it. Somebody somewhere will have the spec.

You can't do a professional job of designing the circuit without the info. Anything else is guesswork, as per Mainline's post.

 

[Skys]

Went to site today the unit was able to switch 230v at 0.5A so a standard contractor was perfect. Thanks for the help