Dimmer Rack Arc Flash

[EdSavoie]

Barring a bad design, aren't almost all dimmers specifically designed to hot swap modules? (Provided you throw the module's breaker of course.)

 

[RonHebbard]

Barring a bad design, aren't almost all dimmers specifically designed to hot swap modules? (Provided you throw the module's breaker of course.)

@EdSavoie Even if you rudely hot swap modules under full load, in theory, many dimmer modules are designed such that the shorter length control contacts break before and make after the physically longer primary and load contacts thus causing the dual-SCR's, TRIACS or IGBT's to cease conduction the moment the next zero crossing point comes along and prior to the heavy power contacts arcing under load.
It's a good theory for a starting pointl.
Toodleoo!
Ron Hebbard.

 

[derekleffew]

Barring a bad design, aren't almost all dimmers specifically designed to hot swap modules? (Provided you throw the module's breaker of course.)

Yes; BUT...

Another quick question, are the original Sensor D20s hot-swappable, or do I need to power down the rack?

Because of NFPA 70E, and its regulations on arc-flash potential, we [ETC] cannot recommend hot-swapping any dimmer module while the rack is powered on. We strongly recommend that you power off the rack before swapping modules to prevent the potential for an arc-flash incident.

@starksk is speaking for ETC. The modules were/are designed to be hot-swappable, but again the old adage applies: Just because one CAN, doesn't mean one SHOULD.

 

[EdSavoie]

I suppose this falls in the same category as moving the lift while up in the air. You shouldn't, but really, you do because the alternative is prohibitively long.

 

[derekleffew]

I do not, sir!

 

[JD]

The thing about hot-swap has less to do with the potential of damaging the module. It is more about what the user may expose once the module is pulled, such as large copper buss bars that are running off a 400 to 600 amp breaker. In someways, some of the older dimmer systems actually were designed safer. For example, still have one of those 150 pound EDI 12x2.4k SCRimmers back in my shed. The modules can be hot swapped. When you pull the module you are not exposed to any hazard. The rear of the module draw has what is basically a female stage pin connector. If you pulled a module it would become fully disconnected before you could make contact with the components in it.

 

[EdSavoie]

Yep, CD-80 Is the same. You'd have to be beyond stupid to get yourself killed by one.

It would take reaching your arm into the newly formed module slot, and sticking your pinky into the live socket.

Although doing something astoundingly stupid like changing the fan while energi- Oh....

 

[RonHebbard]

I do not, sir!

@derekleffew @EdSavoie Certainly never in public on Control Booth!
Toodleoo!
Ron Hebbard.

 

[Jay Ashworth]

Where, teq, by "tag" you mean "sign large enough to read as you run out the door to that room"?