Need a switch.....Four in.........one out

John Morris

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J
Join Date
Sep 2015
Location
San Antonio
Posts
688
Good afternoon All

I have four CT transformers and one digital display. CT signal is 4-20, and the display is scaled 0 to 200 amps.

What I am looking for is a switch that will accept four signals in and narrow it down to one output when selected.

Google is have difficulty interpreting my search requests, so I was hoping to expand my search here.

Any direction given would be greatly appreciated.
 
look up rotary switches
6337.jpg
 
nhatsen said:
https://www.phoenixcontact.com/online/portal/us?uri=pxc-oc-itemdetail:pid=2811815

You select the channel input using 3 digital inputs. In the example they use some PLC's outputs but you can use a binary selector.
Click to expand...

That is definitely the sort of thing John Morris needs - something designed for switching the low-current analog signals.

It would be easy to use just 2 of the 3-binary inputs from a simple rotary switch to select up to 4 of the 8 possible channels.

Another advantage is everything is opto-isolated...
 
And the winner is........RClem

Perfect solution for the application.

So I called to inquire, I was informed they stopped producing that unit three years ago. ( Dammit :)

Guessing a four position rotary with all the outputs wired together?

Mickey...That word never crossed my mind.....thank you

Thank you all for your time and attention
 
Several Manufacturers of Rotary Cam Switches. Many do customs as well as standard configurations. For example, they make a 3 phase voltage switch for meters, where the 1 output selects 1 of 3 inputs (assuming you could common the - side of the 4-20 signals).

Is there an issue opening the 4-20ma current loop, or do you need to short it out when it isn't feeding the meter? If you need to short it, then you'll need overlapping contacts, so the circuit doesn't open between positions...
 
RDS

I dislike having to register for product review, but in this case it was worth it,

They configured an Ammeter switch with five channels in, one out for a Whopping $8.00.

Well done.

Thank you
 
a simple rotary switch from an electronics store will do.
better is to have 4 resistors making the current signal to a Volt signal, or buy 4 displays self powered by the current signal.
 
What happens to the CTs that are switched off (open) at any given time?

What sort of voltage potential will they develop?

I seem to recall a warning about always shorting the CT when not connected to a load.
 

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