Article 430.102(A) - Disconnector within Sight

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wjrez

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This question concerns compliance with Article 430.102(A) for disconnecting means for a motor controller where the controller is integral to the MOV, yet the disconnecting means resides at the MCC and not within sight and when opened will disconnect power to the motor and controller.

By Article 430.102(B), an MCCB at a MCC qualifies as a disconnect for a motor on a MOV because it is capable of being locked in the open position, and the facility uses a lockout-tagout procedure and is maintained and operated by qualified personnel.

By Article 430.102(A), it would appear that another disconnect would be required at the MOV to satisfy the requirement for a controller disconnect.

1. Since the MCCB is a qualified disconnect for the motor, is it not equally qualified to serve as the disconnect for the controller at the MOV? (Control power for the controller is derived internally at the MOV from a control power transformer connected to the main line.)

2. In the above configuration, is an additional disconnect needed local to the MOV, if so why?
 
Re: Article 430.102(A) - Disconnector within Sight

What is the voltage you are dealing with? If it is 600V then the MCCB, which I believe is molded case circuit breaker, in your MCC would qualify as your controller disconnect. However, if your voltage is less than 600V, as I understand 430.102.A you will require a disconnect at the controller. What is an MOV?

Tony
 
Re: Article 430.102(A) - Disconnector within Sight

In a past life of mine, an "MOV" was a "Motor Operated Valve."
 
Re: Article 430.102(A) - Disconnector within Sight

It sounds like you are trying to take credit for the Molded Case Circuit Breaker (MCCB) in the Motor Control Center (MCC) as the single disconnecting means for the motor and the controller of your Motor Operated Valve (MOV). I believe that is acceptable. I think the Exception to 430.102(B), sub-part (b), gives you what you need. The controller for your MOV would be disconnected individually by the MCCB in the MCC. The code says,
. . . provided the disconnecting means required in accordance with 430.102(A) is individually capable of being locked in the open position.
Click to expand...
That means that you must be able to disconnect the controller for the one motor being maintained, without that action also disconnecting the controllers for other motors. That fact that the MOV?s motor will be disconnected by the same action does not alter the situation.
 
Re: Article 430.102(A) - Disconnector within Sight

Charlie,
I don't see any provision that would permit the controller disconenct to be located remotely from the controller.
Don
 
Re: Article 430.102(A) - Disconnector within Sight

Don,

You and I agree on the code interpretation that does not allow an exception for the disconnecting means for the controller. However, I do not see the need if the motor disconnector, which may be not "within sight", disconnects all power to the device. So my question is why is there a need for a disconnecting means local to the controller?

I apologize for not explaining the nomenclature I was using in my original post. I am in the power industry and MCCB (molded case circuit breaker) and MOV (motor operated valve) are common terms. I will try to be more explicit in the future.
 
Re: Article 430.102(A) - Disconnector within Sight

wjrez,
I don't know the reason that the code requires a local disconnect for the controller but permits a remote lockable disconnect for the motor>
Don
 
Re: Article 430.102(A) - Disconnector within Sight

Originally posted by don_resqcapt19: Charlie, I don't see any provision that would permit the controller disconnect to be located remotely from the controller.
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It depends on the voltage level, as Tony said earlier. Odds are that these MOVs are 480 volt or below, which would mean that a local disconnect would be needed. But we don?t know the voltage level yet.
I don't know the reason that the code requires a local disconnect for the controller but permits a remote lockable disconnect for the motor.
Click to expand...
Good point. Nor do I. Furthermore, why would it become OK (translate ?safer?) to have a remote disconnect, but only when you deal with the higher voltages?
 
Re: Article 430.102(A) - Disconnector within Sight

Once again the rookie must apologize for the remiss. I am talking about equipment under 600 volts A.C.
 
Re: Article 430.102(A) - Disconnector within Sight

In the many industrial facilities that I have designed and built, I use 430.102(B) exception (b). There are over 100 MOVs (480V Limitorque) on my current project and it would not be practical to put remote disconnects at all locations. Also, the clients do not want them. You must be careful when locking out the power. It leads one to assume that all circuits are de-energized and you quickly forget about the PLC and DCS equipment that controls that valve.

Brian
 
Re: Article 430.102(A) - Disconnector within Sight

If you have done this, then technically speaking you are not in compliance with the code. Furthermore, the assumption I have regarding the use of a disconnecting means at the controller is exactly as you state. That the PLC or DCS may be providing interrogating voltage to the MOV contacts even though the motor disconnect is opened. However, this is not my case. Yet the code does not provide exception.
 
Re: Article 430.102(A) - Disconnector within Sight

Originally posted by drmoody:
it would not be practical to put remote disconnects at all locations. Also, the clients do not want them.
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I do not think the code cares if it is practical. ;)

We all have clients that would rather not follow the code. :roll:
 
Re: Article 430.102(A) - Disconnector within Sight

To: wjrez, I am going to quote out of the NEC Handbook, Article 100, Definition of a Controller.
CONTROLLER: A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the appapartus to which it is connected.
Now I am going to give you the Handbook interpretation.
A controller may be a remote-controlled magnetic contactor,switch,circuit breaker,or device that is normally used to STOP motors and other apparatus and, in the case of motors,is required to be capable of interrupting the stalled-rotor current of the motor. STOP-AND-START STATIONS and similar control circuit components that do not open the power conductors to the motor are not considered controllers.
So, what I have just said, is that a start-stop pushbutton can serve as the controller for a motor if it opens all of the power conductors to the motor. And you would install the pushbutton within sight of the motor, but no more than 50 feet from the motor.
 
Re: Article 430.102(A) - Disconnector within Sight

IX. Disconnecting Means
430.101 General.
Part IX is intended to require disconnecting means capable of disconnecting motors and controllers from the circuit.
430.102 Location.
(A) Controller. An individual disconnecting means shall be provided for each controller and shall disconnect the controller. The disconnecting means shall be located in sight from the controller location.
Click to expand...
mcc1.jpg


Am I mistaken when I look at this graphic, that it seems to represent the order of devices and controls for motors?
The text of 430.101 seems to indicate that motors AND controllers require disconnecting means capable of disconnecting them?
 
Re: Article 430.102(A) - Disconnector within Sight

I would like you all to look at Section VII. Motor Controllers, in the 2002 NEC.
Section 430.81(A)Definition. For the defintion of Controller, see Article 100.For the purpose of this article, a controller is any switch or device
that is normally used to start and stop a motor by
making and breaking the motor circuit current.

I have been in the chemical industry for many years, and we have always put a start/stop station within sight of the motor,but no further than 50 feet from the motor. When you are in a electrical classified area such as a class 1 division 2, group A,B,C or D, if you had to put a controller with a contactor, or a three or four pole switch, they would have to be explosion-proof. This would be very costly to the Company.
So, we will put a start/stop pushbutton that is rated for the proper classification. I hope that this will clear the matter up about a controller.
If you do not agree with me, please let me know.
 
Re: Article 430.102(A) - Disconnector within Sight

friebel,
A start/stop station that controls a remote magnetic contactor is not a controller because the start/stop station itself does not make and break the motor current.
You can use the the exception to 430.102(B) to eliminate the local motor disconnect.
Don
 
Re: Article 430.102(A) - Disconnector within Sight

Don,I am not in agreement with you on your comment about controllers. Again, I will direct you to the 2002 NEC Part VII.Motor Controllers
Section 430.81(A) Definition. For the definition of Controller, see Article 100. For the purpose of this article, a controller is any switch or device that is normally used to start and stop a motor by making and breaking the motor circuit current.
 
Re: Article 430.102(A) - Disconnector within Sight

friebel,
Unless the start/stop button directly makes and breaks the motor current it is not a conroller. The key is that the controller must make and break the motor current. A start/stop station does not normally make and break the motor current. It only makes and breaks the control circuit current and therefore is not a controller per the definition in 430.81(A).
Don
 
Re: Article 430.102(A) - Disconnector within Sight

friebel,

What I have pasted below is from the NEC handbook, notation after the definition of controller. It supports exactly what Don is saying.

"....Stop-and-start stations and similar control circuit components that do not open the power conductors to the motor are not considered controllers."

tony
 
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