High/Low selector - PLCS.net

sayahan2003 · March 13th, 2018, 02:46 PM

My friends,

If in an application we have flow control with pressure override, or pressure control with level override or something like this, how do we know that the selector should be low select or high select? Is this related to the controller action (direct or reverse)? what if one of the controller is reverse and the other one is direct? or both direct?

Thanks

janner_10 · March 13th, 2018, 04:12 PM

You're gonna have to fix your Google translate or re-phrase that question.

It makes no sense whatsoever.

sayahan2003 · March 13th, 2018, 04:20 PM

Quote:

Originally Posted by janner_10

You're gonna have to fix your Google translate or re-phrase that question.

It makes no sense whatsoever.

you are using the same language for other posts too. If you do not understand, just don't worry about it!

AustralIan · March 13th, 2018, 04:21 PM

You use logic and common sense every time.

"If loop1 wants to drive the output lower and loop 2 wants to drive the output higher, which one would I rather do?"

boneless · March 13th, 2018, 04:40 PM

Example from my world.

I want to get a certain temperature (by slowing down flow through a heat exchanger), but I want a minimum flow. Here the highest of the two determines the output.

I want a certain power use on a boiler, but I don't want to exceed my temperature. Here the lowest of the two determines output.

OkiePC · March 13th, 2018, 04:40 PM

The question makes sense, it is just too generalized to get a good response. Maybe you are looking for general answers. Maybe you have some specific hardware that we can apply the question to...

sayahan2003 · March 13th, 2018, 05:28 PM

Quote:

Originally Posted by boneless

Example from my world.

I want to get a certain temperature (by slowing down flow through a heat exchanger), but I want a minimum flow. Here the highest of the two determines the output.

I want a certain power use on a boiler, but I don't want to exceed my temperature. Here the lowest of the two determines output.

Thanks boneless,
Your example are absolutely correct. My question is how you get to the result at the last sentence of each example(lowest or highest).

sayahan2003 · March 13th, 2018, 05:29 PM

Quote:

Originally Posted by OkiePC

The question makes sense, it is just too generalized to get a good response. Maybe you are looking for general answers. Maybe you have some specific hardware that we can apply the question to...

Thanks OkiePC,

This is a general question. I don't have a specific hardware.

March 13th, 2018, 02:46 PM	#1
sayahan2003 Member Join Date: Jun 2006 Location: Calgary Posts: 179	High/Low selector My friends, If in an application we have flow control with pressure override, or pressure control with level override or something like this, how do we know that the selector should be low select or high select? Is this related to the controller action (direct or reverse)? what if one of the controller is reverse and the other one is direct? or both direct? Thanks

March 13th, 2018, 04:40 PM	#6
OkiePC Lifetime Supporting Member Join Date: Mar 2005 Location: ENE of Nowhere Oklahoma Posts: 9,833	The question makes sense, it is just too generalized to get a good response. Maybe you are looking for general answers. Maybe you have some specific hardware that we can apply the question to... __________________ It's not all the variables I am most concerned with, it's the undiscovered constants.

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March 13th, 2018, 04:12 PM	#2
janner_10 Supporting Member Join Date: Dec 2014 Location: Tewkesbury Posts: 635	You're gonna have to fix your Google translate or re-phrase that question. It makes no sense whatsoever.

March 13th, 2018, 04:21 PM	#4
AustralIan Member Join Date: Jan 2013 Location: UK Posts: 763	You use logic and common sense every time. "If loop1 wants to drive the output lower and loop 2 wants to drive the output higher, which one would I rather do?"

March 13th, 2018, 04:40 PM	#5
boneless Lifetime Supporting Member + Moderator Join Date: Feb 2008 Location: OKC Posts: 1,455	Example from my world. I want to get a certain temperature (by slowing down flow through a heat exchanger), but I want a minimum flow. Here the highest of the two determines the output. I want a certain power use on a boiler, but I don't want to exceed my temperature. Here the lowest of the two determines output.

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