Local/Remote Switches in MCC

[charz]

Is it normal to have Local / Remote switches in both MCC and in LCS near the Motor? I think it is possible to have misoperation with Local / Remote switches in both location.
Is it necessary/code requirement to have Local/remote switches, start/stop push buttons in the MCC? as I would like to have them in the LCS near motor.

 

[jraef]

No code calls for any operator devices, it's totally up to the user.

That said, Local / Remote selectors in two places can create a particularly frustrating troubleshooting experience if you ask me. I would never do that.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[GroovyGuy]

Maintenance personnel really like to have a means to test that the correct motor has been locked-out. A hard-wired local (to the motor) control-station provides that functionality. I prefer a Jog-off-auto selector-switch as the local control station. There is no Code ruling that requires a control-station be installed at either the MCC or the motor.

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[waross]

Mostly I see Hand/Off/Auto switches located at the motor, but for other types of loads such as heat tracing it is common to see Auto/Off/Local switches at the MCC.
Think:
"What will be most convenient for maintenance and trouble shooting?"

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

 

[dpc]

This is probably understood, but a pilot device such as a Local/Remote or HOA switch should NEVER be used as a lockout device. When I was doing electrical design for power plants, we never put pilot devices at the MCC, other tha OL reset. When I did water treatment plants, EVERY motor had an HOA switch at the MCC. It's industry and process specific.

Cheers,

Dave

 

[vijaypandiyan]

L/R switch shall be located with process control who will decide the operation of motor.stop push button in MCC is must , because you cannot go near LCS during some emergency and that time, you can stop motor from MCC. Start PB in MCC is depend upon operation philosophy.

Thanks,
Vijay

 

[LionelHutz]

I've never seen two L/R switches for the same controls. That wouldn't make sense. If you want or need the switch, you typically put it at the location where you want to operate the motor while the local position is selected.

You'd typically put it at the motor when there are local controls at the motor and the operators would manually start and stop the motor while standing near the motor so they could watch the motor and load operate.

 

[dpc]

stop push button in MCC is must

You can't really make a blanket statement like this. I've seen hundreds and hundreds of motor starters with no stop PB at the starter.

 

[bacon4life]

The substation transformers we purchase have two L/R switches. Each transformer has two cabinets. One cabinet is part of the tap changer control cabinet that comes from Reinhausen or ABB. The second cabinet is built by the manufacturer and has the fan controls, the LTC controls, the SCADA interface, the CT terminal blocks etc. Each cabinet has a L/R switch, which certainly has lead to confusion.

 

[jraef]

I may have been premature in stating that "No code calls for any operator devices, it's totally up to the user." Someone I know pointed out to me that although this is true in North America, it is not necessarily true elsewhere in the world and apparently there are some IEC rules regarding motor control cabinets (which may be what you meant by "MCC") that do in fact require a stop device wherever a motor is controlled from.

This is a downside of people asking questions about "codes" without first identifying where in the world they are located. Codes vary quite a bit across the world.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[TugboatEng]

If you are going to go so far as to put local/remote switches at each operating station why not just use pushbutton start and stop at each control station and do away with the selector? This does not apply if you need the equipment to restart automatically after a loss of power, however.

 

[waross]

I normally see Local/Remote switches, or more commonly Hand/Off/Auto Switches for automatically controlled equipment.

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