three Moore Industries 535 controllers, one rosemount transmitter

[arcscott]

Can one Rosemount 3051 d/p transmitter supply signal to three Moore Industries 535 controllers? I have a boiler dearator with one level control valve, one make-up level control valve and one emergency dump valve. Each valve has a controller of its own. Can one Rosemount 3051 provide each controller with a level signal?

 

[waross]

If you use 4-20 mA you may need a little more than 24 Volts loop power. 30 Volts should do.
Check the data sheets for loop loading.


Bill
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"Why not the best?"
Jimmy Carter

 

[ScottyUK]

I am fairly sure that they can, but you will need to be careful if the controllers are intended to use internal loop power.

Make sure the loop supply can drive all three inputs in series (assuming a current loop).


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If we learn from our mistakes I'm getting a great education!

 

[waross]

Hi Scotty. I checked the specs quickly and it looks as if it's close at the common 24 Volts supply. It may work fine but we once had a horror show when an emergency shutdown consistently failed. It turned out that one instrument in the loop was of spec on the input resistor. The loop looked fine on paper but was pushing 24 Volts to the limit. With one input resistor slightly over spec, the power supply could not quite drive the full 20 ma and not quite enough current to reach the high limit set point.
With that in mind I suggested the 30 Volt power supply.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[danw2]

The 353 can be equipped with a retransmitting 4-20mA output. So one of the 353's could restransmit its input signal to another 353's input.

Or you could use a 4-20mA splitter, which produces two 4-20 signals. This Phoenix Contact model can drive 2 devices. each with 250 ohm input resistance and its input resistance is only 50 ohms:

http://rd.phoenixcon.com/products/interface/db/datasheets/MCR-2UI.pdf