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Frequent Contributor

Murphy Switch Problem

OK, Experts,  Here's your challenge for today.

 

Recently added a second well/engine to an irrigation system.  Now I'm using two small diesel engines to pump water from two wells into one pivot system.  When the plumbing was done for piping the water together, an underground conduit was laid, containing a TWO wire service from the pivot to the ancilary engine.  However, it was not hooked up.  The installers told me how to hook it up, and it made sense, but , that was a few months ago, and having slept since then,  I've forgotten the instructions.

 

All the safety systems from the pivot to the original engine work fine, I just can't seem to make things work with the second engine.

 

I want both engines to shut down if there is a safety problem with the pivot.  And if one engine shuts down, I want the other engine to shut down as well.  Can't seem to find the right combination of circuits, pivot safeties, and Murphy switch connections.

 

Anyone wish to take a shot?    Thanks.   KenJ

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3 Replies
Advisor

Re: Murphy Switch Problem

I'm basing this on my experience.  Yours may be different....  I am assuming there is a start/run switch?   It bypasses the pivot system until it is operational then switches from bypassing to working.  You start the engine, get the pivot going, then throw the switch to use the pivot safety system.  If you don't have this you may have a similar switch on the pivot panel.  Currently you have a pair of wires going from engine 1 to the pivot. If these wires do not make a closed circuit the Murphy shuts off the engine.  If something happens to the pivot safety system it opens the circuit (either by opening a switch or unlatching a relay) that causes the Murphy to shut down engine 1

 

What you are going to do is wire the Murphy for engine 2 in line with engine 1  I suggest installing a bypass switch on either the panel or engine 1 for engine 2.  You're going to wire it so the circuit going from engine 1 to the pivot now also has to go to engine 2.  But to get everything going you need a way to bypass it until it is operational.

 

Does this make sense or have I just muddied the water farther?

 

It's incredibly simple once you figure it out.

2 engine diagram.jpg

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Veteran Advisor

Re: Murphy Switch Problem

On my setup, the wires ground out the 'trigger' on the Murphy system, instead of being engergized to hold the run button in.  I think either way would work, but you need to know how yours is wired in order to get it right.  If you make the wire 'hot' when it should only be grounded when the Murphy is activated, it will not shut the engine off.  If you make it grounded, when it shoud be 'hot', you will drain batteries, or more likely, blow fuses.

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Advisor

Re: Murphy Switch Problem

That's why I started out with "I'm basing this on my experience.  Yours may be different...."  I only deal with 4 systems and they are all wired like I mentioned.  If there is not continuity though the entire system mine shuts down.

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