Starter Auxiliary Contact Usage

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Jim1959

Senior Member
Location
Longmont, CO
CURRENT SENSING RELAY

CURRENT SENSING RELAY

installing a current sensing relay on one of the motor leads will really tell you if the motor is running.
 

templdl

Senior Member
Location
Wisconsin
I may have missed but did the OP ever reply with what type of contactor they had? Should the manufacturers and model of the contactor be know just maybe there are other options. But then again it's more fun to brain storm just to find something that a simple NO contact would do.
 

Jraef

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Electrical Engineer
I may have missed but did the OP ever reply with what type of contactor they had? Should the manufacturers and model of the contactor be know just maybe there are other options. But then again it's more fun to brain storm just to find something that a simple NO contact would do.
Well, in the absence of further input, all we have is this kind of speculation.
 

templdl

Senior Member
Location
Wisconsin
Well, in the absence of further input, all we have is this kind of speculation.

Interesting. Isn't it similar to shooting at shadows? When simply knowing the make and model of the contactor would be benificial in quickly and accurately addressing the spplication?l?
By not answering a simple question shouldn't there be some concern regarding the techniical knowledge that the OP has?
 

Jraef

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Staff member
Location
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Electrical Engineer
Interesting. Isn't it similar to shooting at shadows? When simply knowing the make and model of the contactor would be benificial in quickly and accurately addressing the spplication?l?
By not answering a simple question shouldn't there be some concern regarding the techniical knowledge that the OP has?
Or, to give him the benefit of the doubt, he got his answer in iwire's first response as I said earlier and saw no need to look in again... In other words he may have simply been unaware that you could add more aux contacts until iwire said it, so he went back, found out that was right, and moved on, leaving us with yet another unsolved mystery to ponder and pontificate on. :roll:
 

Jraef

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distributed control system.
A Distributed Control System is typically (now) a mini computer (more than a PC) running a network of smaller computers and/or PLCs together to handle a large processing facility, like a chemical plant or a refinery. You will typically have a big control room with a wall of monitors running complex graphics of all of the individual process control loops.
Industrial_Process_Control.jpg

The short version, which was the opening line of a long boring training course I took once, was this:

"PLCs make things, a DCS makes stuff."
 

templdl

Senior Member
Location
Wisconsin
Or, to give him the benefit of the doubt, he got his answer in iwire's first response as I said earlier and saw no need to look in again... In other words he may have simply been unaware that you could add more aux contacts until iwire said it, so he went back, found out that was right, and moved on, leaving us with yet another unsolved mystery to ponder and pontificate on. :roll:
And that's the way it should work. And to think how many rabbet trsils there were which I would think would confuse the OP when a basic and correct answer we would suffice.
 

kwired

Electron manager
Location
NE Nebraska
A Distributed Control System is typically (now) a mini computer (more than a PC) running a network of smaller computers and/or PLCs together to handle a large processing facility, like a chemical plant or a refinery. You will typically have a big control room with a wall of monitors running complex graphics of all of the individual process control loops.
View attachment 15832

The short version, which was the opening line of a long boring training course I took once, was this:

"PLCs make things, a DCS makes stuff."
If one has that complex of a control system and you look at the OP mentioning "so when the starter closes the aux contacts close, which completes a circuit back to our DCS telling it that the motor is running." I would think knowing as much about the process conditions as possible is likely a high priority. A simple aux contact on a motor starter is not that great of a positive indication that a motor is running. At the most it can only mean the controller is in run position. This may be reasonable enough if the control method is nothing more then a start-stop switch with pilot light for a running indicator in some applications but the complexity of the system here likely needs current sensor(s) or even sensors on the driven load to tell the status of that item.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
If one has that complex of a control system and you look at the OP mentioning "so when the starter closes the aux contacts close, which completes a circuit back to our DCS telling it that the motor is running." I would think knowing as much about the process conditions as possible is likely a high priority. A simple aux contact on a motor starter is not that great of a positive indication that a motor is running. At the most it can only mean the controller is in run position. This may be reasonable enough if the control method is nothing more then a start-stop switch with pilot light for a running indicator in some applications but the complexity of the system here likely needs current sensor(s) or even sensors on the driven load to tell the status of that item.
No argument from me, that's why I've been using solid state OL relays. Current flow = On, no current flow = Off. I don't care what the contactor says. It catches the occasional mistake of when someone leaves a disconnect open at the motor. The other thing I like is on anything with a belt, I look at the current with the belt disconnected and that becomes my lower threshold instead of zero current. Sure the contactor is closed and some current is flowing, but if the belt is broken, none of that matters.
 
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