Emergency Stops

[alsslp]

I have a pumping station with three pumps in one room and the VFD's and disconnects in another room. Near each motor I have a mushroom pushbutton for an emergency stop. The emergency stop will not restart the motors once it is pushed, a start command has to be given at the VFD to restart the motors.
Is an emergency stop reqyuired near the motors?
Is the emergency stop button considered a contoller?
Does push button need to be lockable?
Does push button need to indicate ON/OFF?

 

[don_resqcapt19]

Re: Emergency Stops

No to all of your questions, but 430.102(B) may require a disconnect within sight of the motors.
Don

 

[wyedelta]

Re: Emergency Stops

All of your question has been answered by our moderator.I would like to add something about lockable push button.We used this lockable push button for emergency stop to add more safety.If you use this type nobody can start the motor in main controller unless the button is reset, in this case the worker who initiated this action is little more safe.But if you just use ordinary stop button there is a tendency to start the motor without knowing somebody stop it for some reason.

 

[don_resqcapt19]

Re: Emergency Stops

wyedelta,
The use of lockable stop buttons in the control circuit can be misleading to those who are required to lockout the equipment before working on it. A locked stop button does not comply with the OSHA rules for lockout/tagout. The power source itself must be locked out.
Don

 

[wyedelta]

Re: Emergency Stops

don

I am talking about emergency stop button in remote control area and not in main controller.In the event of emergency this button cut out the supply to the machinery thru de-energizing main contactor but not the main supply.I agree to the lock and tag which totally isolated the main supply but for the emergency means it only discontinue the operation of the machinery that is why a lockable emergency stop button is more prefer that the ordinary one.I hope I am clear.this does not violate any rules.

 

[tom baker]

Re: Emergency Stops

A e stop is not required by Art 430, and it does not meet the intent of 430.102. The estop is not a controller, it is part of the control circuit. See the article 100 defintion of Controller.
An e stop is not required, but can be a good additional safety feature.

 

[don_resqcapt19]

Re: Emergency Stops

wywdelta,
I still see the lockable stop button as a danger. Someone will lock it and think that it is safe to work on the equipment. It is not.
Don

 

[hurk27]

Re: Emergency Stops

wywdelta,
Emg stops even lockable one's do not remove power from equipment to render them safe to work on. disconect's do. With the Emg. stop pushed in there will still be power on the control wiring and on the motor starter. and if a contact on the motor starter were to weld shut it would allow voltage to be present on that phase at the motor This thinking could cause someone unknowingly be electrocuted when they go to change a bad motor.

 

[tom baker]

Re: Emergency Stops

wyedelta:
Review the definitions for controller, disconnecting means, and within sight.