Control/Dimming New to Dimmer Racks

S

Shawncfer

Active Member
So I'm sure most of yall are use to me askin stupid questions, but I got another one for you. It's just that I don't have a tech teacher and I like tech, so my high school theatre teachers taught me all they knew about tech, and I've been trying to learn as much as I can on my own.

So Anyway, on to the question.

I know at my school we have ETC sensor install rack.
This website tells the different types : http://users.wpi.edu/~theatre/res/resources/Manuals/Lighting/L_Sensor+Rack_S.pdf

So a couple questions. First of all, each Dimmer thats in there is actually two dimmers right? If the makes sense? So each one goes to two outlets in the end? And If I am right, it says it's 2.4kW each. now does that mean that each dimmer is 2.4kW And since it's 2 dimmers in each rack its 1.2kW to each?

I hope I didnt make myself sound more stupid. Thanks for the help.
 
No. Each dimmer is 2.4kw, so each unit handles 4.8kw (two time 2.4)

This is a learning forum, there are no stupid questions as long as they are from the heart.
 
Not all dimmer racks have dual dimmer modules, but many install racks happen to be configured that way. An ETC Sensor+ rack with 48 dual 2.4kW (aka 20amp) rack will have 96 dimmers total. The 2.4kW refers to each, individual dimmer.

One dimmer will feed one circuit. This could be a single outlet or dozens of outlets. Either way, however many outlets it feeds, it is only able to power up to 2.4kW across the entire circuit. If there are ten outlets, each pulling 240W, then the dimmers will handle the load fine. If there are 250W on each outlet, then the 2500W will overload the circuit and eventually the breaker will flip.

Dimmer modules can usually be exchanged out for other types of modules. Instead of a D20's, other common modules are R20's, AFM's, and CC20's. R20's are relays that allow circuits to be remotely turned on and off. AFM's are just blank, air flow modules, that will not provide any electrical source for circuits. CC20's are constant circuits, acting as glorified, standard 20A circuit breakers, such as you would find in your home.

2.4kW modules are common because three 750w fixtures can be placed on a single circuit, as can up to four 575w fixtures. However, as lamps have become more efficient and dimmers more plentiful, many theatres do not use more than one or two fixtures per circuit, so 1.2kW (aka 10A) dimmers can also be used in place of 2.4kW modules.

Just as you can have lower power ratings than 20A, you can also have higher ones as well. For big lights or large house lighting circuits 50A and 100A dimmer modules may also be found in dimmer racks, but they are not very common.

If you aren't well-versed in electricity, here is where the numbers add up:

voltage * current = power

120v * 10A = 1.2kW
120v * 20A = 2.4kW
120v * 50A = 6kW
120v * 100A = 12kW

A 2.4kW circuit is synonymous with a 20A circuit, provided you are using 120v circuits. (most conventional lighting in North America is 120v. Some movers are 208v, 220v, or 240v, and dimmer-doubled lights may be 77v, but 120v is the most common in theatres).

EDIT:
Note that one dimmer will feed one circuit in most installs, however a single dimmer may feed two circuits if dimmer doublers are used. This is a whole 'nother beast that you can learn more about by searching the forums)
 
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Shawncfer said:
...I know at my school we have ETC sensor install rack.
This website tells the different types : http://users.wpi.edu/~theatre/res/resources/Manuals/Lighting/L_Sensor+Rack_S.pdf

So a couple questions. First of all, each Dimmer thats in there is actually two dimmers right? If the makes sense? So each one goes to two outlets in the end? And If I am right, it says it's 2.4kW each. now does that mean that each dimmer is 2.4kW And since it's 2 dimmers in each rack its 1.2kW to each?

I hope I didnt make myself sound more stupid. Thanks for the help.
Click to expand...

As the subtitle of the forum says: "The only stupid question is the one you didn't ask!"

There are a couple of different types of Sensor Installation racks. There are Sensor "Classic" racks (most easily identified by the three red LEDs at the top of the rack called the Beacon) which use either an MPE (SR6 or SR12 only) controller (has three red rotary selector switches for start address) or CEM (Control Electronics Module) (has a number pad on the face panel) to control the rack.
And there are Sensor+ Racks (most easily identified by the Blue Beacon, and also the type that your linked data sheet points out) which use a CEM+ (has +,-,Check and Back arrow) to control it.

On to your real question: the answer is a definite maybe. The number of circuits that a module can control will depend on the type of module. Most modules have two individual dimming circuits. Each one is rated for its specific output. The most common example of this is the D20 module which has 2 - 2.4Kw Dimming circuits. The easiest way to tell how many circuits a dimming module can control is to look at the number of circuit breakers on the module.

We try to keep the code for figuring out what each module is rated for pretty simple. A D20 has a 20A circuit breaker per circuit, a D50AF has a 50A breaker, a D100AF has a 100A breaker, and so on...


There are several different modules available to meet what load types are going to be connected to the circuit. Check out this product page for a listing of the current modules available for a Sensor+ System.

As to how many outlets are wired to the circuit, that is more a function of who has designed the space. There may be only one outlet wired to a circuit or there may be several outlets wired to the same circuit. The key is to know how much current you can draw per circuit and not to exceed that amount.

Edit: Apparently several of us were typing at the same time.
 
Thank you! haha now just a couple more questions

1,whats the difference between Three Phase and Single Phase?

2,I see that it has direct ethernet input. So does that mean if I have a newer board that has ethernet output I can run it straight to the rack? And if so can I run in with Ethernet and out with DMX into another fixture or rack? Or can I run in with Ethernet and out with Ethernet?

3, What cable runs out of the rack to the lights? Is it Socapex? Or another kind? If there is another kind.

4, Is a Dimmer Doubler just makes it have two outputs instead of having to twofer?

5, What are these options:
Amp-Trap® fuse
Bussing kit for 2 - 12-module racks
19" Auxiliary Rack(s) for 12-module rack

Sorry for so many questions:neutral:
 
Ha okay well apparently I had a couple replies while I typed that last one which raised another question.

What happens if you do overload the circut?

And the AFM module, is that just like an extra fan to keep it cool???
 
Shawncfer said:
Thank you! haha now just a couple more questions

1,whats the difference between Three Phase and Single Phase?

2,I see that it has direct ethernet input. So does that mean if I have a newer board that has ethernet output I can run it straight to the rack? And if so can I run in with Ethernet and out with DMX into another fixture or rack? Or can I run in with Ethernet and out with Ethernet?

3, What cable runs out of the rack to the lights? Is it Socapex? Or another kind? If there is another kind.

4, Is a Dimmer Doubler just makes it have two outputs instead of having to twofer?

5, What are these options:
Amp-Trap® fuse
Bussing kit for 2 - 12-module racks
19" Auxiliary Rack(s) for 12-module rack

Sorry for so many questions:neutral:

[6]What happens if you do overload the circut?

[7] And the AFM module, is that just like an extra fan to keep it cool???
Click to expand...

Question 1: I would encourage you to search this forum as there have been several threads on it. Search results for Three phase vs. Single Phase

Question 2: This will depend on which control module you are talking about. If it is the CEM classic, the port on the front is an RJ45 connector, but is not actually using ethernet nor networking protocol. If it is a CEM+, the CEM+ will listen to EDMX (ETCNet2) or sACN (streaming ACN) for its control signal. If you have a console that outputs either of those two protocols onto your lighting network, then you can connect straight to the rack through a switch and control your lighting rack. As for coming in with ethernet and out with DMX, this is a complicated yes. That feature is something that a service technician should setup for you.

Question 3: Usually in install racks, it is simply building wire gauged to the appropriate size for the circuit. It is not usually multi-conductor cable as that is both expensive and usually hard to pull through conduit.

Question 4: Sort-of. It takes the sinewave of the power coming on the circuit and splits it so that the top half of the sinewave becomes A and the bottom half becomes B. This means that roughly half of the voltage is used by one side and the other side uses the other half. To use this feature, you will need the special Dimmer Doubler two-fer as well as 77V lamps in your Source 4 Fixtures that are connected to these circuits.

Question 5: Amp-Traps are used when the rack is being fed more power than it is rated for (usually in situations where multiple racks are being fed off the same incoming source). We do not recommend this, but there are situations in places where it is necessary.
A bussing kit is used when you have two (or more) racks powered from the same feed. It passes the power from the buss bar in rack 1 to the buss bar in rack 2, 3, etc...
An Aux Rack is used to give more space for the electrician to land the incoming feed wire. It can also house a main circuit breaker so that the rack's disconnect is right next to it saving time in trying to figure out where the d**n breaker is located.

Question [6]: Ideally, the breaker will trip stopping the potential for fire and other bad things from happening. Because each breaker has a little bit of wiggle room in the amount of overcurrent it takes to trip, you can also potentially damage the power cube in the dimmer module if you stay in that state for a long enough period of time. (A power cube is the SCR/SSR/Triac/etc... that controls how the module dims)

Question [7]: The AFM is a blank put in place to maintain the proper airflow of the rack. The fan at the top draws air through the door and filter, (which should always be kept closed when not accessing the modules or control module,) up through the rest of the modules, and out the top. This is necessary to keep the dimmers from overheating.
 
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Shawncfer said:
Thank you! haha now just a couple more questions

1,whats the difference between Three Phase and Single Phase?


3, What cable runs out of the rack to the lights? Is it Socapex? Or another kind? If there is another kind.

4, Is a Dimmer Doubler just makes it have two outputs instead of having to twofer?


Sorry for so many questions:neutral:
Click to expand...

I know that 1,3 and 4 have been discussed at great length in the recent past, so you might try a search. The answers to your (very good) questions can be long winded.

I'm not exactly well-versed enough in Dimmer Doubling to give you the exact explanation on how it works, but I can tell you what it does. It's much more than a two-fer. Dimmer Doubling works in conjunction with ETC Source Four's utilizing a special 77v lamp. In extremely simplified terms, it's *like* a two-fer, in that you can plug in two lights and control them both. Only, with Dimmer Doubling, you can control them each independently as if they were on two different dimmers.

As for what happens when a dimmer is overloaded; hopefully the circuit breaker will trip, just like if you were to overload a circuit in your house. If that circuit breaker was to fail to trip, you would probably end up with an overheated dimmer module, and most likely some magic smoke to go along with it.

ETC dimmers are rated for 100% load 100% of the time. Meaning you can run 2,400w on a 2,400 dimmer for as long as you want with no ill effects.
 
Just a tad more on dimmer doubling (Although it is covered on other threads.):

A standard D20 module has two dimmer circuits, and is controlled by two channels on the board. With dimmer doubling you would now have four separate board channels controlling four separate and independent lamp circuits using the same two channel module. In other words, doubling the amount of channels and control you have. It does not increase the available power and is dependent on the following:
1) You rack must support the software to do it. (Call ETC)
2) You must use special adapters between the rack and the fixtures to split out the A & B channels.
3) You must use special 77 volt lamps.
4) You -should- use different plugs on the adapters and fixtures that are equipped with 77 volt lamps for obvious reasons.

It's a great way of getting more control channels out of the existing system, provided you can put up with all the special requirements.
 
Okay, so I searched the forums, and googled, and read alot about single phase and three phase. But there are still a couple questions...

Is there an advantage to three phase over single phase as far as dimmer racks go?

So at my school we have an install rack and i've never seen the power supply, however where I work theres this pannel that they connect wires two, one on the left, one on bottom, one on the right so on... (ill put a pic later)... Is this the power supply? And how do you know which one goes to which?

And if the Nuetral isn't necesary in three phase, why does it exist?
 
JCarroll said:
in short... every phase is a sine wave
single phase is one phase. 120v
2 phase is two single phases 180 degrees off. 240v
3 phase is three single phases 120 degrees off from each other.120v phase to neutral... 208v phase to phase

the neutral is used for 120v but is required as a safety feature.*

*new to this 3 phase stuff... someone correct me if I'm wrong
Click to expand...

Correction two single phases 180 degree's off is STILL Single Phase or it is sometimes referred to as "Split Phase"

Three Phase dimming systems still have a Neutral as the Neutral is required to pull 120v out of a three phase system and the potential difference between any of the three phases and Neutral is 120v while the potential between two hot phases is 208v. In a dimming system you rarely if ever connect phase to phase as there aren't many lamps that run on 208v. So in a dimming system the three phases are just used in a phase to neutral configuration to give 120v. The first 1/3 of the dimmers run on Phase A, the second third runs on Phase B and the last third runs on Phase C.

Single Phase systems use 2 phases but are still referred to as Single Phase or sometimes Split Phase and consist of two phases 180 degrees apart, a neutral and a ground. The potential between phases is 240v and the potential between ether of the phases and neutral is 120v. This is how you get 240v in your home for things like electric ovens, stovetops and dryers...etc.

Three Phase power is almost exclusively only used in Commercial/Industrial applications it is very rare to find it in someone's home. Single Phase is pretty much the opposite as it is only really found in Residential homes and older buildings.
 
Sony said:
So in a dimming system the three phases are just used in a phase to neutral configuration to give 120v. The first 1/3 of the dimmers run on Phase A, the second third runs on Phase B and the last third runs on Phase C.
Click to expand...

So in Dimming systems, how is it set up with single phase?

And THEORETICALLY speaking... If each 1/3 of the dimmers is run on 1 of the phases, and the phases are 120v each. THEORETICALLY could a regular house outlet?

And still, is there an advantage to three phase over single?

And who decideds weather your dimmers are run off single or three? Do you choose what you want? Or is it dependent on how your facility is set up?
 
Shawncfer said:
So in Dimming systems, how is it set up with single phase?

And THEORETICALLY speaking... If each 1/3 of the dimmers is run on 1 of the phases, and the phases are 120v each. THEORETICALLY could a regular house outlet?

And still, is there an advantage to three phase over single?

And who decideds weather your dimmers are run off single or three? Do you choose what you want? Or is it dependent on how your facility is set up?
Click to expand...

In single phase it is setup pretty much the same as Three Phase except the first half of the dimmers is on one phase and the second half is on the other.

Yes, a regular house outlet can run on one phase of a three phase system, in fact this is pretty much how all commercial buildings are wired. Each circuit with an outlet on it is on one of the three phases

The advantage of a three phase system comes from power consumption, electric motors and lighting systems run much more efficiently on a three phase system and therefore consume less power. In a commercial building where you have lots of large motors and lighting the power savings over time is huge. Another advantage is that power from the power plant is naturally generated in three phase anyways and therefore transmission and distribution of three phase power is less complicated.

The choice of single or three phase dimming is dependent on how your facility is setup, if it is a brand new commercial building then there is a 99.9% chance it will be three phase. If your facility is older or maybe you are doing a special production in a historical space or something of that nature then you may have Single Phase. It all depends on the building, but any qualified electrician will be able to determine which type of power you have and what equipment you will need. I suggest you leave it up to him/her.
 
Okay Last question Sony.

Is it possible for you to run single phase one day and three phase the next?

For example, if I have a live venue and bands are always on tour stopping all with their own lights and everything. Can one band use single and then the next day a different band uses three? Or does it depend on the venue? And does the rack have to be set up for which ever phase you have? So if a band buys a touring rack, and then their first show its single and the second show is three, is that possible with one rack?
 
In most cases, if you have three-phase, it can be used however it needs to be used. Assuming you have 120v/208v "Wye", groups can tie-in their dimmer racks and hook up all three-phases, while loading it phase-to-neutral for 120v. Other groups just have to connect their fixtures phase-to-phase to tap into the 208v for their movers and motors (such as chain hoists and winch systems).

There are not many actual three-phase loads in theatre, most are single-phase loads that happen to be on three-phase systems. Having a three-phase system is pretty much synonymous with having three, single-phase legs (provided the legs are all 120deg apart).

However, if you only have a single-phase system at your disposal, that's all you can use it as. The legs will be likely be 180deg apart, with the phase-to-neutral voltage at 120v, and the phase-to-phase voltage at 240v. This is your typical residential system.
 
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