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Old October 14th, 2011, 07:27 AM   #1
agarb
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Local/Off/Remote Selector Switches & Continuous Processes

Is an Local-Off-Remote switch just another name for a Hand-Off-Auto switch?

If so, I assume that a LOR switch would be implemented similar to the HOA switch in the attached pdf.

I am normally used to working on stand-alone machinery that performs a specific sequence and then repeats after being unloaded and loaded by an operator.

Now consider some machinery running a continuous process. There are approximately 10 motors which all must be running and remain running for the process to continue. Why would a customer specify that they want LOR switches for all the motors? It seems to me that there would be the danger of somebody walking by and turning off one motor thus disrupting the entire process. The process in question is not trivial to start up, especially if not "emptied" out properly before stopping.

Thoughts? How are LOR switches implemented in your facility?
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Old October 14th, 2011, 09:06 AM   #2
Lancie1
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Quote:
Why would a customer specify that they want LOR switches for all the motors?
Your customer could want Local switches: 1. To test the motor and what it does without running the entire system, 2. To allow manual operation when the Remote device fails.

Yes, there is a danger that someone could switch to Local when he should not. However, without the Local mode, there is a danger that your Remote device will fail and the owner will be left with nothing. What this says (one way or another) is that he does not completely trust what you are using and doing.

I always request Local-Off-Remote or Hand-Off-Auto switches everywhere that is appropriate, because I, too, am not a trusting guy.

Last edited by Lancie1; October 14th, 2011 at 09:09 AM.
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