DOOR INTERLOCK

[timmer]

we would like to paralell a door safety interlock with a " captive " key, would be used for infrared scanning on a VFD only once a year . ---insert key --turn key --safety switch is now bypassed .open door , VFD stays running ,complete the scan,remove key , door safety switch now active ,
Any downsides to bypassing door safety?

 

[rc/retired]

we would like to paralell a door safety interlock with a " captive " key, would be used for infrared scanning on a VFD only once a year . ---insert key --turn key --safety switch is now bypassed .open door , VFD stays running ,complete the scan,remove key , door safety switch now active ,
Any downsides to bypassing door safety?

NEC no. I don't believe the building code would have an issue with this either.

 

[petersonra]

we would like to paralell a door safety interlock with a " captive " key, would be used for infrared scanning on a VFD only once a year . ---insert key --turn key --safety switch is now bypassed .open door , VFD stays running ,complete the scan,remove key , door safety switch now active ,
Any downsides to bypassing door safety?

Most such switches come with a built in bypass feature. Why would you need to add one?

 

[tom baker]

Its not an NEC issue, but would be addressed via a SOP

 

[infinity]

Is there any code that actually requires an interlock on the VFD? If not then there should be no issue disabling it.

 

[roger]

We use to install THESE, might be something to consider.

Roger

 

[petersonra]

I am trying to think why anybody would want to do an infrared study of a VFD. If the VFD overheats it will just shut itself off and you will know.

 

[EC Dan]

Door interlocks in general are intended to be and designed to be defeatable by qualified personnel to perform maintenance. The downsides are of course exposure to arc flash and the considerations of limited/restricted approach boundary.

 

[timmer]

I am trying to think why anybody would want to do an infrared study of a VFD. If the VFD overheats it will just shut itself off and you will know.

not to be rude, but that's why its called PREVENTATIVE MAINTENANCE, it's always better to find a problem before it becomes a catastrophie

 

[petersonra]

not to be rude, but that's why its called PREVENTATIVE MAINTENANCE, it's always better to find a problem before it becomes a catastrophie

these kind of infrared studies almost never find anything useful. Particularly on an active device where you don't know what the load actually is. However in most cases you can just tap on the keypad and find out what the temperature of the heat sink is which is probably a more useful measurement and requires no fancy gear or opening of the door assuming the keypad is mounted in the enclosure door where it should be.