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Title: Anatomy of large scale power distro
Post by: Paul John Volzone on March 19, 2011, 01:44:29 am
Im just curious to know how exactly power gets from the 480 v 3 phase feeders down to amp racks, dimmer modules and stage power.green white black red blue?... multi pin power connectors?...anatomy of a distro box? etc?  Just trying to learn and understand so i can have an idea of whats going on if i ever see it. :o
Title: Re: Anatomy of large scale power distro
Post by: David Parker on March 19, 2011, 10:08:54 am
Im just curious to know how exactly power gets from the 480 v 3 phase feeders down to amp racks, dimmer modules and stage power.green white black red blue?... multi pin power connectors?...anatomy of a distro box? etc?  Just trying to learn and understand so i can have an idea of whats going on if i ever see it. :o

first thing you're going to have to have is a transformer to get the 480v down to 240v, at least for the amps. There might be dimmer packs that run on 480v, but all I've seen run on 240/120.
Title: Re: Anatomy of large scale power distro
Post by: Mac Kerr on March 19, 2011, 10:26:54 am
Im just curious to know how exactly power gets from the 480 v 3 phase feeders down to amp racks, dimmer modules and stage power.green white black red blue?... multi pin power connectors?...anatomy of a distro box? etc?  Just trying to learn and understand so i can have an idea of whats going on if i ever see it. :o

In most cases the venue supplies 208V 3 with an appropriate amp rating. It is common to see 100A, 200A, 400A, or 800A services available for production. In really big venues you may see 1200A or up to 3000A service. There are usually at least 2 services, 1 for lighting and 1 for sound. There may be multiples of each. Often this is delivered from a transformer brought right to where you need it, or it may be a company switch with cam lock outputs, or a switch where you need to tie bare ends into the lugs. Any active venue should have cam locks. Those cams will be color coded, green, white, black, red, and blue for ground, neutral, phase x, phase y, and phase z. They must be connected in that order, and disconnected in reverse order. Many cam lock panels have interlocks so that you can only connect them in the proper order.

Once the power is at your distro there will be a 3 mains breaker to match the capacity of the distro, which then feeds the internal distribution of the panel to breakers for each circuit, and on to the individual power outlets. There may also be 3 outlets on the panel, with 3 breakers.

Each department takes the size switch they need, in my case it is usually 100A 3 for sound, I have taken as much as 400A, and that is probably more common on big concert rigs (what I had that day). Each department, sound, lighting, video, rigging, runs their own 5 wire 3 cam lock feeder cable from the company switch to their distro, where the power gets distributed on the types of connectors they use, and at the amperage ratings per circuit they need. If they are not active during the show, rigging may share power with another department.

Often on big concert rigs there will be more than 1 sound distro, commonly there will be one stage left and one stage right to supply power to the amp racks located on each side of the stage. Putting out, and striking, 50' to a couple hundred feet of 5 wire 2 aught feeder cable is one of the most tedious and backbreaking parts of the job, but without it, nothing else happens.

Mac
Title: Re: Anatomy of large scale power distro
Post by: Joe Brugnoni on March 19, 2011, 12:38:20 pm
In most cases the venue supplies 208V 3 with an appropriate amp rating. It is common to see 100A, 200A, 400A, or 800A services available for production. In really big venues you may see 1200A or up to 3000A service. There are usually at least 2 services, 1 for lighting and 1 for sound. There may be multiples of each. Often this is delivered from a transformer brought right to where you need it, or it may be a company switch with cam lock outputs, or a switch where you need to tie bare ends into the lugs. Any active venue should have cam locks. Those cams will be color coded, green, white, black, red, and blue for ground, neutral, phase x, phase y, and phase z. They must be connected in that order, and disconnected in reverse order. Many cam lock panels have interlocks so that you can only connect them in the proper order.

Once the power is at your distro there will be a 3 mains breaker to match the capacity of the distro, which then feeds the internal distribution of the panel to breakers for each circuit, and on to the individual power outlets. There may also be 3 outlets on the panel, with 3 breakers.

Each department takes the size switch they need, in my case it is usually 100A 3 for sound, I have taken as much as 400A, and that is probably more common on big concert rigs (what I had that day). Each department, sound, lighting, video, rigging, runs their own 5 wire 3 cam lock feeder cable from the company switch to their distro, where the power gets distributed on the types of connectors they use, and at the amperage ratings per circuit they need. If they are not active during the show, rigging may share power with another department.

Often on big concert rigs there will be more than 1 sound distro, commonly there will be one stage left and one stage right to supply power to the amp racks located on each side of the stage. Putting out, and striking, 50' to a couple hundred feet of 5 wire 2 aught feeder cable is one of the most tedious and backbreaking parts of the job, but without it, nothing else happens.

Mac
Great post Mac!!
Title: Re: Anatomy of large scale power distro
Post by: Sheldon Harris on March 19, 2011, 08:50:35 pm
In most cases the venue supplies 208V 3 with an appropriate amp rating. It is common to see 100A, 200A, 400A, or 800A services available for production. In really big venues you may see 1200A or up to 3000A service. There are usually at least 2 services, 1 for lighting and 1 for sound. There may be multiples of each. Often this is delivered from a transformer brought right to where you need it, or it may be a company switch with cam lock outputs, or a switch where you need to tie bare ends into the lugs. Any active venue should have cam locks. Those cams will be color coded, green, white, black, red, and blue for ground, neutral, phase x, phase y, and phase z. They must be connected in that order, and disconnected in reverse order. Many cam lock panels have interlocks so that you can only connect them in the proper order.

Once the power is at your distro there will be a 3 mains breaker to match the capacity of the distro, which then feeds the internal distribution of the panel to breakers for each circuit, and on to the individual power outlets. There may also be 3 outlets on the panel, with 3 breakers.

Each department takes the size switch they need, in my case it is usually 100A 3 for sound, I have taken as much as 400A, and that is probably more common on big concert rigs (what I had that day). Each department, sound, lighting, video, rigging, runs their own 5 wire 3 cam lock feeder cable from the company switch to their distro, where the power gets distributed on the types of connectors they use, and at the amperage ratings per circuit they need. If they are not active during the show, rigging may share power with another department.

Often on big concert rigs there will be more than 1 sound distro, commonly there will be one stage left and one stage right to supply power to the amp racks located on each side of the stage. Putting out, and striking, 50' to a couple hundred feet of 5 wire 2 aught feeder cable is one of the most tedious and backbreaking parts of the job, but without it, nothing else happens.

Mac

well said mac,
most active venues do have cams, the part i do not like sometimes, is what those cams are attached to on the other end. especially so in the case of hotels when you already know what the HUGE PRICE is for the feed.
sheldon
Title: Re: Anatomy of large scale power distro
Post by: Mac Kerr on March 19, 2011, 08:53:19 pm
the part i do not like sometimes, is what those cams are attached to on the other end. especially so in the case of hotels when you already know what the HUGE PRICE is for the feed.
sheldon

I don't know what you are trying to say here. Please explain.

Mac
Title: Re: Anatomy of large scale power distro
Post by: Sheldon Harris on March 19, 2011, 09:06:48 pm
I don't know what you are trying to say here. Please explain.

Mac

mac,
i was making a comment based on what you said" all active venues do have cams as feeders.
i went on to say ( not that you commented on it in your post) that sometimes i do not like what they are connected to, (corroded terminals,questionable sub panels etc>)
and especially, for hotels ( they charge a lot of money for the feeds) that are sometimes questionable.
shldon 
Title: Re: Anatomy of large scale power distro
Post by: Brian Larson on March 21, 2011, 07:01:55 pm
Live Sound Theory & Practice by Mark Amundson is a great resource for power as it relates to the production world.

http://www.amazon.com/Live-Sound-Practice-Theory-Book/dp/0979810701

Also take a look at some images of sine waves, it helps to visualize this sort of thing.

http://www.google.com/images?hl=en&safe=off&q=three+phase+power&bav=on.2,or.r_gc.r_pw.&um=1&ie=UTF-8&source=og&sa=N&tab=wi&biw=1036&bih=1029
Title: Re: Anatomy of large scale power distro
Post by: Paul John Volzone on March 24, 2011, 03:03:12 pm
In most cases the venue supplies 208V 3 with an appropriate amp rating. It is common to see 100A, 200A, 400A, or 800A services available for production. In really big venues you may see 1200A or up to 3000A service. There are usually at least 2 services, 1 for lighting and 1 for sound. There may be multiples of each. Often this is delivered from a transformer brought right to where you need it, or it may be a company switch with cam lock outputs, or a switch where you need to tie bare ends into the lugs. Any active venue should have cam locks. Those cams will be color coded, green, white, black, red, and blue for ground, neutral, phase x, phase y, and phase z. They must be connected in that order, and disconnected in reverse order. Many cam lock panels have interlocks so that you can only connect them in the proper order.

Once the power is at your distro there will be a 3 mains breaker to match the capacity of the distro, which then feeds the internal distribution of the panel to breakers for each circuit, and on to the individual power outlets. There may also be 3 outlets on the panel, with 3 breakers.

Each department takes the size switch they need, in my case it is usually 100A 3 for sound, I have taken as much as 400A, and that is probably more common on big concert rigs (what I had that day). Each department, sound, lighting, video, rigging, runs their own 5 wire 3 cam lock feeder cable from the company switch to their distro, where the power gets distributed on the types of connectors they use, and at the amperage ratings per circuit they need. If they are not active during the show, rigging may share power with another department.

Often on big concert rigs there will be more than 1 sound distro, commonly there will be one stage left and one stage right to supply power to the amp racks located on each side of the stage. Putting out, and striking, 50' to a couple hundred feet of 5 wire 2 aught feeder cable is one of the most tedious and backbreaking parts of the job, but without it, nothing else happens.

Mac



great post mac. Very informative. so the volatage coming thru those cam lock feeders is usually just 208 volts? and its just the amp service that are usually diff? how many amps (at what voltage) can those feeders carry?
Title: Re: Anatomy of large scale power distro
Post by: Tim McCulloch on March 24, 2011, 04:26:50 pm
great post mac. Very informative. so the volatage coming thru those cam lock feeders is usually just 208 volts? and its just the amp service that are usually diff? how many amps (at what voltage) can those feeders carry?

NEC 400 Flexible Cords and Cables.

It depends on the cable type and any de-rating applied.  Tables in 400.5(A) and 400.5(B) begin your journey.  Type SC rated for 95C has an allowable ampacity of 405 amps.  A current rating, by itself, is irrespective of voltage.  The ampacity is the same at 440/277v. although other wiring devices or switch gear may bring other limitations.
Title: Re: Anatomy of large scale power distro
Post by: Mac Kerr on March 24, 2011, 10:01:14 pm
great post mac. Very informative. so the volatage coming thru those cam lock feeders is usually just 208 volts? and its just the amp service that are usually diff? how many amps (at what voltage) can those feeders carry?

The voltage coming out of those Cam-Lok connectors is 208V relative to each other, it is 120V relative to the neutral or ground (because neutral will be tied to ground at the service entrance). That is standard 3 power in the US. If the service is single phase there will be 2 hot legs that are 240V relative to each other, and 120V relative to the neutral. In most professional venues the service is 3.

The service will be sized appropriately for the type of venue as far as ampacity.

Feeder is usually 00 or 0000 gauge depending on how much power will be pulled through that feeder.

Mac
Title: Re: Anatomy of large scale power distro
Post by: Albert Thomas on March 24, 2011, 10:39:47 pm
Im just curious to know how exactly power gets from the 480 v 3 phase feeders down to amp racks, dimmer modules and stage power.green white black red blue?... multi pin power connectors?...anatomy of a distro box? etc?  Just trying to learn and understand so i can have an idea of whats going on if i ever see it. :o

Lot's of good info posted here. I'd just like to add a word of caution to the inexperienced as to the safety hazards present when you get into these kind of current availabilities. You can get some serious burns or die if things aren't done right. I've been an electrician working with 3 phase high currents for 30 years and have seen some ugly injuries. If you're not 100% sure of what you're doing, ASK! Don't assume, it'll help keep you out of the emergency room.