float contact controls

[tolind]

I'm installing a couple of floats in a process water pit. I need the floats to active a light and turn a pump on. Is this possible with one float? I guess to make it clearer, can you control two seperate items with one float??

Thanks in advance

 

[davidbeach]

If the float has multiple contacts you can do that directly. If the float only has one contact, use that contact to drive a relay and let the relay control the other items.

 

[ScottyUK]

Using an interposing relay would be good practice anyway: relays are usually cheaper and less hassle to replace when, for instance, a pump motor fault occurs and passes a high fault current through the switch. If the pump is anything over a couple of hundred watts you should be using a contactor for switching the pump instead of a relay. You could drive the lamp from a spare pole or auxiliary switch mounted on the contactor.

You could in theory just parallel the lamp and the motor if they were of compatible voltage, but this would be a real cheap and dirty way to do things.


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One day my ship will come in.
But with my luck, I'll be at the airport!

 

[jraef]

There are mechanical float switches that provide an adjustable dead band of operation, so that you can use one device that has a single contact which closes when the level reaches "X" height, but does not reset (open) until the level is "X + Y" height. This technical information article explains how they work and what the issues are to applying them, but you can find other manufacturers by looking for "sump operation" level controls.

http://www.ab.com/en/epub/catalogs/12768/229240/2286210/229278/tab3.html[/URL]] AB Float Switch article link

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