Control/Dimming - NSI DDS 9800 power question

[mcorder]

We have an NSI DDS 9800 dimmer pack. It is set up for 120/240v single phase 2 pole. The facility only has 208/120 3-phase. Is there any reason this pack would not work with two phases of the 3-phase? It looks like the dimmer modules are simply split between the 2 poles. Is anyone else using a dds-9800 on 3-phase power in this way? Leviton's tech support was no help, simply citing the published specs, go figure....

Thanks much. This is my first post, long time reader. I love this site .

[epimetheus]

Here is the link to the DDS 9800 Manual if you didn't already have it.

http://www.leviton.com/OA_HTML/ibcGe...BE&appName=IBE

My quick look at the manual tells me the 9800 is only designed for "120/240VAC 80 amp 2 pole 3 wire plus ground only." The 9600 can be configured for single phase or 3 phase, but the 9800 is only designed for single phase.

In other words, the 9800 is not designed for 208VAC and running it on such a voltage, even if it would work (I'm not saying it will), would be against code as I imagine the dimmer is not UL listed at that voltage.

[JD]

The following is copied from page 3 of their manual:


The NSI DDS rack dimmers must be provided with a proper electrical service as listed below:
*8600 : 120/240 VAC 20 amp 3 pole 4 wire plus ground (use minimum #10 AWG) or
120/240 VAC 30 amp 2 pole 3 wire plus ground (use minimum #8 AWG).
8800 : 120/240 VAC 40 amp 2 pole 3 wire plus ground only (use minimum #6 AWG).
*9600 : 120/240 VAC 40 amp 3 pole 4 wire plus ground (use minimum #4 AWG) or
120/240 VAC 60 amp 2 pole 3 wire plus ground (use minimum #4 AWG).
9800 : 120/240 VAC 80 amp 2 pole 3 wire plus ground only (use minimum #2 AWG).
* Unit set up for 3 pole 4 wire - for 2 pole 3 wire operation see Service Manual.

Somewhat humorous! One would have thought that would have been caught on the proofreading.

In any case, the dimmers themselves only know about the 120 volt part. The primary difference in dimmer designs has to do with looking for the zero voltage cross point. A single phase dimmer would only parse one phase. A three phase dimmer would parse three legs. The manual shows two power transformers in 9800 which would be a good indicator that both legs are being parsed separately. Somewhat odd, but it looks like it would work just fine. I would give the manufacturer a call and get it from the horse's mouth.
All things being said, running dimmers off of two legs of three phase power sure leaves the load unbalanced.

[epimetheus]

I noticed that error JD, at least they got it right on the first page of the manual!

[SHARYNF]

I have used some 8600's and in the service manual for them there is a proceedure to convert from three phase/single phase
Basically there is the option to move the connections from leg 3 over to leg 1 and leg two. I would talk with NSI but I would guess that they have a similar approach on the 9800 where you could move them back to full three phase supply. If I recall properly these are really all 120 volt dimmers, and so each module is just being fed 120 volts. There are three binding posts market l1 l2 l3 inside and the service manual shows either splitting them across three legs or across 2 legs
Sharyn

[epimetheus]

Originally Posted by SHARYNF

I have used some 8600's and in the service manual for them there is a proceedure to convert from three phase/single phase
Basically there is the option to move the connections from leg 3 over to leg 1 and leg two. I would talk with NSI but I would guess that they have a similar approach on the 9800 where you could move them back to full three phase supply. If I recall properly these are really all 120 volt dimmers, and so each module is just being fed 120 volts. There are three binding posts market l1 l2 l3 inside and the service manual shows either splitting them across three legs or across 2 legs
Sharyn

The manual I linked is the manual for the whole DDS series. You can only do the single to three phase conversion on the *600 packs, i.e. the 6 channel packs. The *800 8 channel packs only have L1 and L2 connections per the manual. My guess is that they allow that on the 6 channel packs because you can evenly split the channels across the phases, not so much on the 8 channel packs.

I agree with the comments above that running that pack on 2 legs of a 208Y/120V system will probably work. I'm curious what running it like this does to the UL listing of the pack.

[SHARYNF]

I knew there was a reason to go with the 6 channel packs ;-)

since it says 120v I would say that it will work OK since each leg is going to be 120 volts. IF it only said 240 volts than it probably would not work. The design AFAIK does not take a 240 volt supply and then split it down via a transformer system, but it instead takes two 120 volt feeds and basically feeds the two banks directly.
Since the UL listing is 120/240 I would say you are OK vs if it only said 240

Sharyn

[JD]

I would venture a bet that most of these units are installed in locations that are 120/208. There are just not too many commercial/theater type buildings that are wired in single phase, other then a few of those with tapped delta feeds.

[epimetheus]

Originally Posted by JD

I would venture a bet that most of these units are installed in locations that are 120/208. There are just not too many commercial/theater type buildings that are wired in single phase, other then a few of those with tapped delta feeds.

My last church had that tapped delta config and NSI dimmers, so I'm pretty familiar with that config now. To be honest, I hate it.

[JD]

Yea, HVAC guys are probably the only people that like them. As for lighting and sound, it's about as thrilling as finding out wasps made a nest under the panel cover.