Disconnect Switch Requirement

[jaykool]

I have to feed a bunch of VFDs from MCC breaker buckets.

The VFDs are in an separate electrical room.

I am guessing that I need disconnect switches for each drive since the MCCs are not in the line of sight.

I looked for verbiage in article 430 stating so...but did not see.

 

[Eng]

Check the specs, an HOA switch may be required and this will serve as your disconnecting means.

 

[jaykool]

We will have jog-auto-off switches in the field...but not with the vfd/reactor enclosure.

 

[kwired]

Check the specs, an HOA switch may be required and this will serve as your disconnecting means.

A HOA switch does not meet any of the requirments of a motor or motor controller disconnecting means, it is simply a control device. Look at part IX of article 430.

 

[don_resqcapt19]

Are the VFDs in the same room as the MCC buckets? If so you must have a disconnect within sight from the controller (VFD). There are a couple of exceptions but not for common applications.

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.​

​

 

[Eng]

A HOA switch does not meet any of the requirments of a motor or motor controller disconnecting means, it is simply a control device. Look at part IX of article 430.

Thanks

 

[jaykool]

that answers my question, the MCCs are in a different building from the VFDs...therefore I will need to provide disconnects.

 

[Jraef]

Check the specs, an HOA switch may be required and this will serve as your disconnecting means.

Incorrect!

You need a disconnecting means, i.e an AIR GAP type disconnect switch or lockable circuit breaker. It generally has to be in "direct line of sight" to the motor, meaning if someone is about to stick his hands into the machine, he can glance over DIRECTLY to the disconnect device and see HIS lock on it before he risks life and limb. A control device does NOT qualify for that. Read this, it explains it very well.

But there are exceptions under certain conditions in which you can use a remote disconnect, such as a breaker in an MCC or switchboard that has a lockable handle. It has to be a facility that has established monitored safety procedures for Lock-Out/Tag-Out and a safety dept. that qualifies workers etc. (I'm on a remote PC and I can't remember off the top of my head exactly how that is worded, forgive me). There are also signage requirements for the exceptions as well I believe. If you don't know, then you probably don't qualify and should put a disconnect in line of sight to the motor, i.e. at the VFD.

If you have to put it down stream of the VFD, please read this thread I just posted in another forum.

 

[don_resqcapt19]

Incorrect!

You need a disconnecting means, i.e an AIR GAP type disconnect switch or lockable circuit breaker. It generally has to be in "direct line of sight" to the motor, meaning if someone is about to stick his hands into the machine, he can glance over DIRECTLY to the disconnect device and see HIS lock on it before he risks life and limb. A control device does NOT qualify for that. Read this, it explains it very well.

But there are exceptions under certain conditions in which you can use a remote disconnect, such as a breaker in an MCC or switchboard that has a lockable handle. It has to be a facility that has established monitored safety procedures for Lock-Out/Tag-Out and a safety dept. that qualifies workers etc. (I'm on a remote PC and I can't remember off the top of my head exactly how that is worded, forgive me). There are also signage requirements for the exceptions as well I believe. If you don't know, then you probably don't qualify and should put a disconnect in line of sight to the motor, i.e. at the VFD.

If you have to put it down stream of the VFD, please read this thread I just posted in another forum.

We have two different disconnect rules. It appears that you are talking about the required motor disconnect. The exceptions for the required controller disconnect are much more limited than those for the motor disconnect. There is no provision for a remote lockable controller disconnect for controllers that operate at 600 volts or less.

 

[rcwilson]

My interpretation of 430.102 is that the disconnecting means for the controller always has to be within sight of the controller.

The expections allow for the motor disconnect to be out of sight of the motor if it is lockable and other conditions apply.

A VFD is a controller, so the disconnect always has to be within sight of the VFD.

 

[Jraef]

Yes, I was referring to the motor disconnect rules. I just noticed the way the OP asked the question he appears to be referring to the controller disconnect. My mistake.

So yes, the disconnect must be within sight of the controller, so the MCC buckets in another room would not count for that purpose.

 

[IamJonscranium]

Are the VFDs in the same room as the MCC buckets? If so you must have a disconnect within sight from the controller (VFD). There are a couple of exceptions but not for common applications.


[/LEFT]

If the MCC is lockable, you don't need a disc in sight, correct? As long as each VFD is on it's own bucket?

ETA: This has been cleared up already. Looks like I have a bit of reading to do.

ETA2: So you can have a remote, lockable disconnect with signage on a Controller OVER 600V. What is the reason behind allowing this for over 600, but not under?

 

[jaykool]

I agree with Bob's assessment.

No disconnect required for motor out in process area, we have a detailed lockout-tagout-try out policy.

A disconnect is required for VFD since it is a controller (430.102A) and the power source (MCC) is in a separate building.