Question about relays

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pickleman

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Hello all, firs just to give a short rundown of the process I am trying to control. I am the maintenance manager for a pickle company and we have 6 small brine tanks (6 different flavors) that feed one machine (the same machine makes all 6 products with minor changeovers) and we overfill the containers with brine so that there is no air inside the container so we have a capture pan the captures all of the excess brine and pumps it back into the respective tank. So right now there is one pump with one float at the end of a pvc pipe and when they change flavors we just move the pipe with the float into the correct tank, it is not that I want it done. so, I recently made a small control panel to control one sump pump with float switches from each tank. I made it so that each float operates a relay which sends the power to a terminal strip which sends power to the pump. The obvious thing here is that with the terminal strip it backfeeds the power to the other relays, which I know isnt the right way to do it but there is only one selector switch to operate everything and I am using timer relays just to be safe. My question is, how can I wire it so that it does not backfeed to all of the other relays? PLC? I have to make one or two more controls panels like this for other parts of the plant and I would like to do it right and safe. Thanks in advance for any help.
 
Some of the electronic orientated guys can give you particulars but I have seen similar situations where a diode is placed in the circuit. Any one supply will close the relay and not backfeed to the other circuits thru the diode.
 
pickleman said:
Hello all, firs just to give a short rundown of the process I am trying to control. I am the maintenance manager for a pickle company and we have 6 small brine tanks (6 different flavors) that feed one machine (the same machine makes all 6 products with minor changeovers) and we overfill the containers with brine so that there is no air inside the container so we have a capture pan the captures all of the excess brine and pumps it back into the respective tank. So right now there is one pump with one float at the end of a pvc pipe and when they change flavors we just move the pipe with the float into the correct tank, it is not that I want it done. so, I recently made a small control panel to control one sump pump with float switches from each tank. I made it so that each float operates a relay which sends the power to a terminal strip which sends power to the pump. The obvious thing here is that with the terminal strip it backfeeds the power to the other relays, which I know isnt the right way to do it but there is only one selector switch to operate everything and I am using timer relays just to be safe. My question is, how can I wire it so that it does not backfeed to all of the other relays? PLC? I have to make one or two more controls panels like this for other parts of the plant and I would like to do it right and safe. Thanks in advance for any help.
Click to expand...
Can you provide a drawing?
That would make it easier to offer constructive comments.
 
If I were you, I'd just use one smart relay (aka micro-PLC)... say an 8 input, 4 output model (most common AFAIK).
 
pickleman said:
... I recently made a small control panel to control one sump pump with float switches from each tank. I made it so that each float operates a relay which sends the power to a terminal strip which sends power to the pump.

... The obvious thing here is that with the terminal strip it backfeeds the power to the other relays,

... there is only one selector switch to operate everything and I am using timer relays just to be safe.

... how can I wire it so that it does not backfeed to all of the other relays?

...I have to make one or two more controls panels like this for other parts of the plant and I would like to do it right and safe.
Click to expand...

Here is my translation:
You have six float switches - each with an interposing relay. All six relay output contacts are in parallel and any one will turn on the pump. There is a six position switch that either disables the inputs to all but one of the relays, or disables all but one of the relay output contacts - either one is okay.

What about this do you see as unsafe or not right? Is it that one side of the relay output contacts is hot - and the other side is hot when the pump is running because one of the other relays is pulled in? If so, is this an issue with troubleshooting? Or something else?

Is the answer just a 2pole switch to isolate both sides?

I'm not seeing your concerns.
 
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