When L21-30 just isn't big enough

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Rick Stansby

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Feb 1, 2011
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We are trying to figure out how to power our new amp racks that have 4@ Lab PLM20000Qs each. Each amp really needs a full 30A (or more), so an L21-30 won't do. We have considered using a pair of L21-30s to each rack, but there are a lot issues associated with that (no room for pass-thru on the rack-pack, custom rack-packs cost more, and we would have to run 2 cables to each amp rack). I am familiar with the 63A 3phase Ceeform connectors, but we don't see them very often in the US. If we switch to these connectors we will have to get the proper outlets added to at least one of our distros, also we will need new power cables to the amp racks.

I mention the 120V current needs, but in fact we plan on running the amps at 208v once we get the power worked out. At 208v we need about 50A per leg, which is why we are looking at dual L21-30 or single 63A Ceeform.

Is anyone here using ceeforms for amp rack power? Who made the rack-pack?

Does anyone else have any other good suggestions to power these racks? Cam seems a little bit overboard, but not buy much.

We currently use Cam, L21-30, L5-30 and edison exclusively.

P.S. I like the crown V-rack power panels.
 
Re: When L21-30 just isn't big enough

Rick Stansby said:
We are trying to figure out how to power our new amp racks that have 4@ Lab PLM20000Qs each. Each amp really needs a full 30A (or more), so an L21-30 won't do. We have considered using a pair of L21-30s to each rack, but there are a lot issues associated with that (no room for pass-thru on the rack-pack, custom rack-packs cost more, and we would have to run 2 cables to each amp rack). I am familiar with the 63A 3phase Ceeform connectors, but we don't see them very often in the US. If we switch to these connectors we will have to get the proper outlets added to at least one of our distros, also we will need new power cables to the amp racks.

I mention the 120V current needs, but in fact we plan on running the amps at 208v once we get the power worked out. At 208v we need about 50A per leg, which is why we are looking at dual L21-30 or single 63A Ceeform.

Is anyone here using ceeforms for amp rack power? Who made the rack-pack?

Does anyone else have any other good suggestions to power these racks? Cam seems a little bit overboard, but not buy much.

We currently use Cam, L21-30, L5-30 and edison exclusively.

P.S. I like the crown V-rack power panels.
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There's many varieties of Pin and Sleeve connectors that could work, but you are looking at quite a bit of cash outlay as those connectors can be quite expensive! I would stick with the dual L21-30 arrangement since you already have the existing infrastructure.
 
Re: When L21-30 just isn't big enough

Bennett
I doubt if he does need a full 30A, but I would be reluctant to put two on one 30A breaker , especially if these plm20k's are to be on sub duty. Not for nothin, we use California connectors for all of our racks.
 
Re: When L21-30 just isn't big enough

Bennett Prescott said:
Rick,

How have you determined that you need a "full 30A (or more)"?

What about the California Standard connectors, 50a 240v twistlock? I see a lot more of those than any of the CeeForm connectors.
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By popping a 30A breaker using a PLM14000 on subs, and by getting into the PAL limiting from time to time on the same amp.

Even if 30A a leg is enough, we still need something more than an L21-30 to power 4 amps.

We have considered the Cal connectors, but with only 2 legs of 50A we don't get much more than a single L21-30
 
Re: When L21-30 just isn't big enough

The 50A California connector isn't really a step up from an L21-30 if you can balance the load between the phases. The next step up if you don't want to go with cam is pin and sleeve, probably in a 60A/3-phase version.

Lab Gruppen appears to be limiting line current on that amplifier to 30A at 120V or 17.3A at 208, so you may be fine putting 2 on a 30A line/line feed. If you really want to allot each amplifier 30A, you could drop down to 3 in a rack (30A on each of 3 phases of the L21-30).


Me, I'd try putting 2 amplifiers line/line on an L21-30, drive the snot out of them in the shop, and measure the current. If the breaker doesn't hold, I'd move up to cam as the input for the racks, probably split phase given that you have an even number of amplifiers. #2 banded isn't really any worse to coil than the 4/5 you'd need with 60A pin and sleeve.
 
Re: When L21-30 just isn't big enough

Bennett and Rob,
Thanks.

We originally planned on 3 amps per rack, and that is what we are running now. We decided to go up to 4 amps per rack, and we have the 8 new amps, but now the power is giving us head-aches. The idea was that more amps per rack means fewer racks, fewer input/output panels, etc.

There are a lot of advantages to us if we run 4 amps per rack, and my boss is sort of sold on the idea.
 
Re: When L21-30 just isn't big enough

Rob Timmerman said:
Lab Gruppen appears to be limiting line current on that amplifier to 30A at 120V or 17.3A at 208, so you may be fine putting 2 on a 30A line/line feed. If you really want to allot each amplifier 30A, you could drop down to 3 in a rack (30A on each of 3 phases of the L21-30).
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Based on the power draw specs, I think you are correct. Even if we had a bigger breaker, it doesn't look like the amp will ever draw more than 30A, and we are probably always going to get into the PAL limiting if we push it close to the edge.

If we run at 208, then we have the potential for 34 amps per leg, but really only the sub amp is running full tilt, so we would probably be OK. I just don't want to have to keep the amps throttled back at all times. Why buy these big amps if we can't use everything they have to offer.

Maybe 4 amps per rack is a bad idea.
 
Re: When L21-30 just isn't big enough

Why not 2 amps per rack? I have my I-Techs set up in 'suitcase' style racks, 4U each with connectors on the ends, with an L14-30 inlet and passthrough for each rack. The racks don't have wheels because they weigh less than 100 pounds and have a handle on top.

The switch from shockmount pullover racks with wheels to these suitcase style racks I can stowe anywhere has saved an incredible amount of space. And, my suitcase racks stack vertically on the ends, on their sides horizontally, or on wheeled carts. And they're truck pack. From my perspective, it's win-win-win-win!
 
Re: When L21-30 just isn't big enough

The California connector divides up better than l1430. Meaning he could put two amps on 20A breakers and two on 30A breakers, which is likely a better compromise than L1430 where two amps would have to share a single 30A breaker. I do however think 60A pin sleeve is the way to go.
 
Re: When L21-30 just isn't big enough

Brandon G Romanowski said:
The California connector divides up better than l1430. Meaning he could put two amps on 20A breakers and two on 30A breakers, which is likely a better compromise than L1430 where two amps would have to share a single 30A breaker. I do however think 60A pin sleeve is the way to go.
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Two amps on an L14-30 means each amp gets a 30 amp leg. I doubt there is any amplifier designed anywhere that needs more than 30 amps at 120 volts to operate correctly.
 
Re: When L21-30 just isn't big enough

Brandon G Romanowski said:
If he has 4 amps in the rack there would be one 30A leg with two amplifiers on it
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Brandon, I was specifically referring to my case of putting only two amps in a rack, with each amp getting it's own leg:

Why not 2 amps per rack? ... with an L14-30 inlet and passthrough for each rack.
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