HOA Switch

[ATSman]

Regarding ind. light colors, I wonder if there is a standard (UL, IEEE, NEMA, etc) for the colors.

 

[ATSman]

https://www.google.com/search?q=ind...IBgGQBgiSBwEyoAfoCQ&sclient=gws-wiz-serp#ip=1

Ha, take your pick!

 

[LarryFine]

"One philosophy is: Red = ON/OPEN; Green = OFF/CLOSED"

Isn't this contradictory in itself? Don't ON = CLOSED and OFF = OPEN?

 

[petersonra]

"One philosophy is: Red = ON/OPEN; Green = OFF/CLOSED"

Isn't this contradictory in itself? Don't ON = CLOSED and OFF = OPEN?

Sounds like a process plant. Think open = valve open.

 

[jim dungar]

"One philosophy is: Red = ON/OPEN; Green = OFF/CLOSED"

Isn't this contradictory in itself? Don't ON = CLOSED and OFF = OPEN?

Another philosophy was: to change the motors state, push the button that is the same color as the light.
Red = On then push the Red button to Stop.
Green = Off then push the Green button to Start.

 

[kwired]

IF you want an Off position (and most people do), you want it in the middle. The middle OFF position ensures that you have to pass through Off to change the operating mode and that helps to prevent it from being inadvertently left in the wrong position. So for example if the switch was "Off - Hand - Auto", and you had it Off while testing something, you might flip it to Hand and not ALL THE WAY to Auto, then leave, thinking it was in Auto because it was running. That could be bad. Otherwise, just use a 2 position switch that is just Hand or Auto, but for safety reasons, most people don't want that.

In a lot of irrigation pump panels, the switch is "Auto - Off - Hand - Start" with a spring return from Start to Hand.

Only arrangement I ever seen on pump panels around here is HOA maintained all three positions. Separate start button starts it when selector is in hand position. Square D, Allen Bradley, Siemens, GE, Cutler Hammer all are that way around these parts. Have not seen a new GE or Cutler Hammer in years though there are older ones around.

 

[ptonsparky]

Those two MCCs with no selector switches had pilot lights on some of the doors. Hit and miss as to if they were functioning.

 

[kwired]

Another philosophy was: to change the motors state, push the button that is the same color as the light.
Red = On then push the Red button to Stop.
Green = Off then push the Green button to Start.

Which is what I typically seen when they use illuminated start and stop push buttons.

Add: I read what you said again I guess what I typically seen is Red for illuminated stop button and Green for illuminated start button. Start is illuminated when the control is "on" red is illuminated when the control is "off"

If a stand alone indicator light or an illuminated selector switch you may end up with all sorts of color variety and reasoning.

 

[garbo]

Please tell me the reasons why "OFF" is in the middle. Could it be HAO (i.e. transition from one control location to another without turning the system off)?

Best reason in modern times if a motor was running off a VFD. If we had a vibration problem on a fan or pump noises at full speed I would turn down the maximum speed ( Hertz from 60 to 50 to 55 HZ. ) until equipment could be secured to repair the problem. If OFF was the two clicks from auto it would speed up while it was being moved thru the hand position. Have came across several HOA selector switches that for so.e unknown reason while in hand position controls such as pressure or limit switches were bypassed. If drive was in auto and a safety device was holding it from operating and hand was in the center position motor might start up. ( if safeties were bypassed in hand ). One old place that I did work in had 8 old ammonia compressors and when they had trouble with belts slipping on start up the ran no more then two of them in hand that bypassed the pressure switch allowing compressor running entire production shift.

 

[garbo]

For switch gear, I have always seen Red for closed, Green for open. Recently had a customer that wanted it changed the other way around. I made an excuse not to. For motors, usually Green for running, Red for stopped, but not always. For switchgear, I bet there is a standard; for motors, maybe not.

Worked at a newspaper where each press unit ( at least ten units per press ) had a Run Safe buttons on all four corners. Red button & rec light was for ready and green button & green light was a safe was on ( press would not inch or run ) .

 

[jim dungar]

I believe NFPA 79 has some pilot light color suggestions.
Many of the old, pre PLC, control schemes are no longer 'typical', but those of us that do service work still run into them.

 

[Jraef]

For switch gear, I have always seen Red for closed, Green for open. Recently had a customer that wanted it changed the other way around. I made an excuse not to. For motors, usually Green for running, Red for stopped, but not always. For switchgear, I bet there is a standard; for motors, maybe not.

This is known as the "Stoplight Debate" on button / light colors. There IS an "official" standard in NFPA-79 for industrial machinery controls. It is DIFFERENT for push buttons vs indicating lights, then for SWITCHGEAR, it is not the same.

For LIGHTS, Red = On / Dangerous operating conditions, Green = Ready / Safe operating conditions.

For PUSH BUTTONS, Red = Stop, Green = Start. But it does flip in SWITCHGEAR, where Red = Close, Green = Open. However ANSI, who is the de-facto standard for Switchgear here, does NOT dictate button colors.

It's not really up for debate, however the problem is, LOTS of people IGNORE this standard and have adopted their own.

 

[Eddie702]

Just like cars. PRNDL now at one time it was PNDLR which had reverse next to a foreword gear. Now separated by neutral.

A safety issue.

 

[ptonsparky]

Just like cars. PRNDL now at one time it was PNDLR which had reverse next to a foreword gear. Now separated by neutral.

A safety issue.

It was a heck of a lot easier to 'rock' a car out of a snow bank back then.

 

[kwired]

Best reason in modern times if a motor was running off a VFD. If we had a vibration problem on a fan or pump noises at full speed I would turn down the maximum speed ( Hertz from 60 to 50 to 55 HZ. ) until equipment could be secured to repair the problem. If OFF was the two clicks from auto it would speed up while it was being moved thru the hand position. Have came across several HOA selector switches that for so.e unknown reason while in hand position controls such as pressure or limit switches were bypassed. If drive was in auto and a safety device was holding it from operating and hand was in the center position motor might start up. ( if safeties were bypassed in hand ). One old place that I did work in had 8 old ammonia compressors and when they had trouble with belts slipping on start up the ran no more then two of them in hand that bypassed the pressure switch allowing compressor running entire production shift.

That is the bad thing about a hand position. Production guys get tired of things not working like they think it should in auto, and don't tell maintenance or whoever either, and just put it in hand which can bypass certain limits or interlocking methods for controlling/being controlled by other associated equipment.

A feed conveyor might be interlocked with a process machine, and in auto starts and stops as needed, put it in hand and it won't stop if the process machine is backed up for whatever reason. Then product jams, spills, or whatever.

 

[ptonsparky]

That is the bad thing about a hand position. Production guys get tired of things not working like they think it should in auto, and don't tell maintenance or whoever either, and just put it in hand which can bypass certain limits or interlocking methods for controlling/being controlled by other associated equipment.

A feed conveyor might be interlocked with a process machine, and in auto starts and stops as needed, put it in hand and it won't stop if the process machine is backed up for whatever reason. Then product jams, spills, or whatever.

I fixed that on those I did. Hand operation flashed alarms, sent texts, or shut stuff down.

 

[garbo]

That is the bad thing about a hand position. Production guys get tired of things not working like they think it should in auto, and don't tell maintenance or whoever either, and just put it in hand which can bypass certain limits or interlocking methods for controlling/being controlled by other associated equipment.

A feed conveyor might be interlocked with a process machine, and in auto starts and stops as needed, put it in hand and it won't stop if the process machine is backed up for whatever reason. Then product jams, spills, or whatever.

One of the best situations was at a large newspaper many years ago. They were printing a maybe 40 page advancement section that would be inserted the next day in the Sunday newspaper. Somebody forgot to place the selector switch from hand to auto that transferred poorly printed first couple of hundred papers that sent them to one of the huge shredder/bailers so for over a hour good papers were trashed. Foreman wanted to fire a mailer for all of the waste but he told the boss the hand auto switch was up in the press room and not his job to operate it.