Film-Tech Forum ARCHIVE: Barco DP100. Install question

This is topic Barco DP100. Install question - stinger leg. in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Eric Robinson (Member # 2966) on 10-20-2011, 10:58 PM:

Our electrical panel has a stinger leg on one of the three phases. Im installing a Barco DP100 and am wondering if the orientation of the stinger leg is relevant.

Posted by Mark Gulbrandsen (Member # 72) on 10-21-2011, 07:23 AM:

Watch your maximum AC input with the BARCO. HIgh AC voltage can cause premature or outright failure of the power supplies or the rectifier components. I believe in the DP-100 manual it says absolute maximum is 230 volts ac. Your stinger (high leg) is going to be too high! An inexpensive buck boost transformer can be used to drop that leg down to a managable level. Better yet a 3 phase transformer or three seperate transformers to convert the booth AC into Y from your present Delta configuration would be the best route to go. You's end up with 208 three phase just like any modern new building has and that wold create much love between the AC voltage and the projector.

Posted by Robert Minichino (Member # 3495) on 10-21-2011, 08:23 AM:

I'm not familiar with the specifics of the Barco, but if it requires a neutral (a 3-phase Wye connection), you need a transformer. If it doesn't require a neutral, and uses a Delta connection, all three of your legs are 240V, and it will work fine without a transformer. The one leg is only "high" with respect to the neutral (which comes from the center tap of one of the transformers supplying your building), and if the equipment doesn't use a neutral, this doesn't matter.

Posted by Louis Bornwasser (Member # 3063) on 10-21-2011, 08:46 AM:

Robert is right. Further, even if it is "neutral referenced" it may be possible to orient the phases so that the one (if present) that isn't neutral referenced is on the "stinger."

Sometimes popscorn machines and old Xetron consoles are like this. Louis

Posted by Eric Robinson (Member # 2966) on 10-21-2011, 05:14 PM:

The supply to the Barco does not include a neutral. Only L1, L2, L3, and Ground. I noticed that the Barco lamphouse itself draws power from a line jack connection on the control panel area. There is a line cord which plugs in there and it leads into the compartment where the 3 phase is hooked up. I was thinking I might need to trace it to make sure that this is not connected to the stinger leg. One thing I'm confused about though is that if the Barco projector head has this connection...I would assume it to be 120VAC. If so, how could it get 120VAC from a 3 phase connection that has no Neutral reference?

Posted by Phil Ranucci (Member # 3820) on 10-21-2011, 06:37 PM:

I believe that the electronics (card cage) run on 208VAC. If you look inside the left panel at the top you'll see where they wired the electronics. Barco uses an IEC plug that is wired across 2 phases, so you need to make sure you get 208 across them. It could be OK on 240VAC, but I'm used to 3 phase without any complications.

Posted by Dave Macaulay (Member # 813) on 10-21-2011, 07:46 PM:

The IEC cable jumper is for connecting a UPS for the electronics. It is, indeed, 208/240 VAC.

Posted by Pete Naples (Member # 761) on 10-22-2011, 03:50 AM:

Excuse my ignorance, what is a 'stinger' leg?

I've never ehard of that here in the UK, well Scotland.

Posted by Dave Macaulay (Member # 813) on 10-22-2011, 08:28 AM:

accidental duplicate

Posted by Dave Macaulay (Member # 813) on 10-22-2011, 08:28 AM:

This is an oddball 3-phase distribution wiring, it's not installed now as a rule so you won't see it very often but old industrial area still have it.
It is basically 240V delta with one of the distribution transformer's coils centre tapped to give two 120V legs on that phase. This "dog leg" or "stinger" leg is generally grounded to give 120V power to the facility. The voltage from the stinger to the third phase is not used for anything. This system has no neutral, voltage between any two phases is 240V.
This was popular in the beginning of industrial power distribution. The only 120V load in a factory back then was lighting. The problem is load imbalance, all 120V load is on one phase. Nowadays we have so much 120V stuff the imbalance is serious, so this wiring scheme was abandoned.
To get wye out of this and supply a neutral, you need a transformer.
3-phase loads usually have jumpers or another way to accept delta power, the dogleg won't cause any difficulty unless your machine wants a neutral.
240V is fine for a Barco, European power is normally 240V not 208. 208V is an artifact of our 117V to neutral Wye 3-phase. Single phase power here is 117/234. I don't know what happened to 120/240.

Posted by Monte L Fullmer (Member # 2797) on 10-22-2011, 09:45 PM:

Side question then: where does 277v comes from? I notice that a lot of new large building uses 277 for their lights and for the simple reason of adding more load per breaker and not increasing current demand.

Posted by Pete Naples (Member # 761) on 10-23-2011, 05:47 AM:

Thanks Dave [thumbsup]

Posted by Dave Macaulay (Member # 813) on 10-23-2011, 07:37 AM:

277v is the single leg to neutral voltage from 277/480V 3 phase wye distribution. 277/480v is an alternative to the 347/600v system, both used for commercial and industrial installations. This one is preferred in projects with a lot of motors, motors that can be used on this voltage are readily available and cheaper than the 575V ones needed for the 347/600v system. Most commercial buildings in Toronto have 347/600 and use 347V lighting - again so you can have more fixtures on a 15A breaker.

Posted by Christos Mitsakis (Member # 143) on 10-23-2011, 08:24 AM:

For Pete:

High leg delta

Posted by Eric Robinson (Member # 2966) on 11-04-2011, 09:25 PM:

Thanks everyone. Indeed the card cage seems to be happy with 240VAC. Everything is working fine.