# Sensor vs ET Intelligent Raceway



## thommyboy (Oct 9, 2008)

I am working with a group specing out for a new space. We are looking at a mostly ETC rig in terms of control (Eos main ION studio) and fixtures(S4 ERS, Zoom, PARnel). 
What I would like to know is given the option would you rather have an Entertainment Technology IGBT Intelligent Raceway with the 220v drops and Data runs OR Sensor Racks and have to run additional power and data runs for the intelligent fixtures (VL 3500 wash and spot)


----------



## Footer (Oct 9, 2008)

If you can afford the sensor install, do that. I am a big fan of the smart bar technology if you need 12 to 24 dimmers in a multi purpose space. It saves on wiring and space. I would never attempt to put that system into a large facility just due to scalability concerns. With one of those systems you have a lot more failure points throughout the system, not to mention what you have to go through to reset a breaker. You will be much happier with an installed rack, if you can afford it. However, if the installed rack vs more dimmer question comes up, take the more dimmers. 

I have not worked with one of these systems that flys before, but I do have a feeling they weigh more then a traditional raceway. Be sure to take the weight into consideration. I have been to too many places that require an electric to be married after putting 15 fixture on it because the raceway weighs to much. 

Also, (and ETC will do it) you can get a data drop on every electric as well as a twistlock connection on every electric. These twist lock connection should be wired to a relay module, not a dimmer module, and you will have instant mover power and on every electric. I have this in one of my spaces and its fantastic.


----------



## TimMiller (Oct 9, 2008)

I once did a price sheet for sensor racks and the bars. The bars were going to end up costing much more and the threat of heat was an issue (top of this place would get to be 100+) The big cost came into running all off the power up to the catwalk and all over. Also the problem of having one go out and then you losing a bank rather than just one channel. Also the loading on a per channel basis. I want to say they are only 1200W max so you cannot even plug 2 750's into one dimmer which really made it look bad. The racks turned out to be a much better choice (there is a reason why all of these big install companies are installing racks over bars). Also you have to factor in you can only have 32 bars per dmx output, so the cost of all the extra data runs along with splitters really kicked the price up. What i do is i install a sensor rack, and then next to the rack i install a panel that that provides circuits to the moving lights. I then install the plugs where appropriate throughout the space. Running power for 220 costs the same as running power for 110V except for the cost of plugs which gets expensive quick. There is no since in buying 220V relay modules for the sensor rack and then losing all of your potential dimmer space. It is much more cost effective to just run another panel (if your transformer is big enough, it probably will be, just run the panel off of the same transformer). What also works really well for budget constraints but future upgrades is to run some extra pieces of conduit from the mover power to the catwalk and off stage somewhere incase you decide to add more later on. You never know if you decide to even add some 3 ph in for chain motors b/c your lighing positions from the cat are worthless.

Also its totally worth getting a data drop onto each electric including at least one data drop to the catwalk. Put all of you data drops on a seperate universe than your dimmers.

Also have you actually fully checked out the ION or just word of mouth? I get along better with a strand 520 than i do with an ION but thats my personal opinion. We have been spec-ing the road hog for all new installs, its the same price with a lot more functionality.


----------



## SteveB (Oct 9, 2008)

Pro's and Cons to both

ET IGBT Pro's

- The big claim is less cable needed saving on wiring costs. A circuit breaker panel is needed somewhere for the 3 pole 20 amp breakers going out to the bars, as 3 circuits/dimmers can share a neutral, VS. having to run separate neutrals PER CIRCUIT on a central DPC system.

- Ea. outlet has a local On/Off switch for testing, focus, etc,, easily over-ridden from DMX control. 

- You automatically get DMX at the position, as the bar/box needs control. Not sure how robust the ET network and DMX/Data distro is, though the website lists Ethernet at the raceway, with Pathport available.

- IGBT's are very reliable, and - in theory - you don't run into issues having to reset breakers due to shorts, etc... 

- They come in 1.2kw circuits, which is very appealing, especially given the ETC survey that indicated few loads were above 750, typically. I believe a single 2.4kw IGBT can power dual circuits at 1.2kw, which can be very useful if you suddenly need a 2kw fresnel. Having 1.2kw's, can greatly reduce the cost of wiring. Instead of running 12 - #10's for 6 x 20 amp branch circuits, you run 4 - #10's for either 3x2.4, OR 6x1.2, seems very cost effective. 

ET IGBT Con's:

- Few in use (as compared to Sensor), thus parts ?, support ?, 

- Network/Data distro ?, seemed weak when I looked at it years ago, but back then it was all DMX, now it's Ethernet, which is off-the-shelf stuff, and they're doing Pathway now, so possibly improved.

- Heat ?. Big issue, as the heat load for the theater is now at the raceway, not in a controlled HVAC environment, where dimmer racks want to be. Note that the ET devices are very, very sensitive to heat and care must be taken to guarantee correct air flow around the raceway/boxes, as there are no fans to get air moving.

- Weight ?. This was a HUGE issue for us, as the ET Raceway is a lot heavier then a standard raceway, and if it's not on a winch, I wouldn't do it.

- IGBT's are not a huge improvement to standard SSR's, thus no real advantage, possibly less harmonics ?. Not sure about that. 

- No ability to convert a circuit to dedicated clean power. IGBT's do not power ML's any nicer then an SSR. Thus still a need for dedicated power, though the ET website makes mention of ability to be fed 120 and 208 constant power for ML power. Not sure exactly what they are doing. 


ETC Sensor/Central rack thoughts:.

- Rock solid, parts readily available and will be for ever. ETC support

- Ability to convert a pair of circuits to relay/constant, thus possibly less requirement for a lot of dedicated power everywhere.

- The ETC "System" - I.E., console, dimmers, network and nodes, RRFU's, as well as raceways and distro, is very robust. 

- Everybody uses ETC thus everyone understands it.

ETC Cons:

- Not many, just the need for a lot of separate dedicated power outlets, though the system we are currently designing will spec. as SmartSwitch, which can do 208. I'm not spec'ing 208 though, as very few ML's NEED 208, as all are self sensing and can run off 120, just more circuits needed for a lot of fixtures. Does installing 208 help you with anything else ?. 

My initial $.02

Steve B.


----------



## STEVETERRY (Oct 9, 2008)

thommyboy said:


> I am working with a group specing out for a new space. We are looking at a mostly ETC rig in terms of control (Eos main ION studio) and fixtures(S4 ERS, Zoom, PARnel).
> What I would like to know is given the option would you rather have an Entertainment Technology IGBT Intelligent Raceway with the 220v drops and Data runs OR Sensor Racks and have to run additional power and data runs for the intelligent fixtures (VL 3500 wash and spot)



I have some thoughts on this, and my company Production Arts was probably the first large adopter of ETI IPS dimming in the 90's. Now I work for ETC.

So, with everyone's permission, I will lurk for a while longer before weighing in, so we don't run the risk of turning this thread into a commercial spat until the end.

So we can consider the answer carefully, can you tell us what size of systems you are considering? Please tell us the total number of dimmers and capacity for both the rack and distributed choices.

ST


----------



## derekleffew (Oct 9, 2008)

Thank you for your restraint, STEVETERRY. 

thommyboy, just curious why you're limiting the discussion to an installed rack vs. an IGBT raceway? One would think there would be some savings gained by sourcing everything from one manufacturer. Have you considered the SmartBar and/or SmartModule?

Many of us have seen the Rack vs. "dimmer at the fixture" debate before. In the 1980s some Rock&Roll lighting companies tried to convince us "dimmers in the truss" was the future. I don't know of a single touring company doing that today. Of course, I had the same thoughts about powered speakers.
edit: Research shows that the concept of "dimmer at the fixture" was proposed in _A Digital Lighting System for the Theatre_, Master Thesis of Fine Arts Yale School of Drama pp. 1-48, May 1974 by Dirk Epperson. Once an assistant to LD F. Mitchell Dana, Mr. Epperson today is VP and Co-Founder of http://www.kabira.com/, a software solutions company.


SteveB said:


> ...I'm not spec'ing 208 though, as very few ML's NEED 208, as all are self sensing and can run off 120, just more circuits needed for a lot of fixtures. Does installing 208 help you with anything else ?...


 thommyboy specifically mentioned "VL 3500 wash and spot," which *require* 200-240 VAC, 50/60 Hz.


----------



## thommyboy (Oct 9, 2008)

I am looking for 288 dimmers. The reason I was looking more to the ET intelligent raceways was the scalability. It looked like they could be used for a larger install than the smartbar/smart module. 

I was thinking the raceway also for the ability to place pig tails, DMX and 208 in a single package...though I guess that does increase the chances for a single issue turning into multiple issues.


----------



## DaveySimps (Oct 9, 2008)

I have an install of almost 400 IGBT dimmers on 8 electrics, and have roughly the same size install of sensor racks in another space, and have had both for at least 5 years (the Sensor one longer). I think both are great products, but based on heavy usage, I would recommend the Sensor racks. Definately pay to get the data drops and power for moving lights though. It is a great thing to have.

~Dave


----------



## Footer (Oct 9, 2008)

thommyboy said:


> I am looking for 288 dimmers.



Thats a LOT of heat. Also, a lot of weight. I think you know my vote...


----------



## DaveySimps (Oct 9, 2008)

FYI, heat and weight really are not an issue for us with the ET System. Yes it is more weight, but we move them on standard single purchase counterwirght systems with on real issues. The heat is not an issue at all. 

~Dave


----------



## fredthe (Oct 9, 2008)

As long as space and cooling is available for the racks, that would be the way to go. For that many dimmers, IGBT would only make sense if you were severely space constrained.


----------



## TimMiller (Oct 10, 2008)

There are many 208V movers out on the market that only work on 208-240V. All of these types of movers use magnetic power supplies. Also, many companies run them at 208V through their distro so you drop your amperage load. When it comes to big moving light rigs anything helps. Magnetic ballests are cheaper and less likely to fail over electronic ballasts, though they are less effecient. Also i do not like running anything over 700 watts on a 120V circuit.


----------



## STEVETERRY (Oct 10, 2008)

DaveySimps said:


> I have an install of almost 400 IGBT dimmers on 8 electrics, and have roughly the same size install of sensor racks in another space, and have had both for at least 5 years (the Sensor one longer). I think both are great products, but based on heavy usage, I would recommend the Sensor racks. Definately pay to get the data drops and power for moving lights though. It is a great thing to have.
> 
> ~Dave



Forget the engineering theories and advertising hyperbole---this is real-world and unique experience worth listening to!

And thus, I retire to the sidelines!

ST


----------



## derekleffew (Oct 10, 2008)

thommyboy said:


> ...I was thinking the raceway also for the ability to place pig tails, DMX and 208 in a single package...though I guess that does increase the chances for a single issue turning into multiple issues.


I'm sure ANY (well, almost any) theatrical dimmer and raceway manufacturer can incorporate dimmed 120V, switched 208V, DMX, convenience 120V, and Ethernet outlets in a single raceway. All those panelboards and data-distribution devices have to live somewhere--why not conveniently located in a "dimmer" room?


----------



## STEVETERRY (Oct 10, 2008)

derekleffew said:


> I'm sure ANY (well, almost any) theatrical dimmer and raceway manufacturer can incorporate dimmed 120V, switched 208V, DMX, convenience 120V, and Ethernet outlets in a single raceway. All those panelboards and data-distribution devices have to live somewhere--why not conveniently located in a "dimmer" room?



This follows ST's long-held theory of dimmer economics:

"A dimmer rack is a distribution panel with some free dimmers".

And it's just that, when you factor in the cost of getting from 100,000A of available fault current (on a typical 800A feeder) down to 10,000A of Short Circuit Current Rating on a 20A branch circuit. You can't do it with a single breaker panel, you need many of them--with the associated labor to wire them up.

Do the math with multiple breaker panels and then with modern, high-SCCR dimmer racks: the dimmers are free.

You don't get that with distributed dimmers.

ST


----------



## derekleffew (Oct 10, 2008)

So much for staying on the sidelines.

Slightly different topic. I'm wondering about the future of Entertainment Technology, Inc. ET has had the Bak Pak Individual Dimmer for some time.



Just recently, Strand Lighting has introduced the Light Pack Dimmer.


One cannot help but notice the similarities, and the situation becomes curiouser if one is aware that ET holds a patent on IGBT dimming. 

Of course, Strand and ET are sister companies, under the Genlyte/Philips umbrella. I'm also unclear about the status of ET's Marquee™ console, if anyone would like to enlighten me on that. Strand-ET-Vari*lite-CK-Lightolier-Stonco is certainly a mouthful. Even couriouser is who's missing from the www.genlytecontrols.com page.


----------



## Van (Oct 10, 2008)

Wow There have been a lot of great posts in this thread! Some really great info and opinions. A lot of the variables have been discussed very well. As you can get almost any dimmer package in almost any arrangement; you can get as many data drops and power feeds as you are willing to pay for or can afford, or that your facility will support, I feel a lot of the choice comes down to whether you're a Mac or PC kind of person. I have a deep seated love for IBGT dimmers, I don't like Macs, But I feel IBGTs are sort of the Mac of dimmers. They're a bit more expensive initially, but you simply can't beat them for safety. They have more compatibility across the board like PCs do but they have a much better "Plug and Play" capability. Need to run a motor? Balasted light source? Incandescent? Just plug it inand turn it on. Try that with an SCR.


----------



## derekleffew (Oct 10, 2008)

Could you elaborate more on the safety aspect? And are you saying that I can plug my VL2000s into an IGBT dimmer?


----------



## SteveB (Oct 11, 2008)

Some random thoughts

I'm sorta of facing a similar decision about distributed or collected (dimmer rack) for a new complex going in, in the next few years.

In my mind, I don't see enough advantages to recommend IGBT over SCR, the IGBT does not allow "Non-Dim" power to a ML, so the advantage of "Plug and Play" is not (in my mind) a reality and a Sensor handles a mirror ball motor or gobo rotator just fine, and can at least have dual circuits swapped to relay, which you cannot do with IGBT raceways. IGBT has theoretical advantages in terms of dead short protection, but from a user that has tripped breakers maybe 6 times, on a 300 dimmer Sensor system in 4 years, I don't see any big advantage.

One advantage to IGBT I see, is in a scenario we are facing with 3 FOH catwalks that probably would work well with 32 x 1.2kw dimmers (96 total) across 40 feet or so, all fixtures on individual dimmers @ 1.2kw. The cost savings in wiring "may" be actual,. though ST brings up a very valid point that the labor to install circuit panels for 32x20 amp, 3 pole breakers, as power distro to IGBT raceways, might eat up the savings in copper.

And you still need dedicated power for the ML's of the future. 

As other have pointed out, there are many ML's wanting 208v, though I question as to the application of the larger and brighter ML's that need 208, being needed in smaller spaces. You still need "some" 208 around, so best plan for it, but I have a question - are the fixtures needing 208, using 208 only beceause they are brighter ?, or is the feature set of the larger fixtures what people are after ?. 

The ETC SmartSwitch system, "seems" like a good way to go, but as I discovered, they do not have internal circuit breakers, so you are back to the labor issue of installing and wiring up separate breaker panels alongside the SmartSwitch panel(s), so at what point is it cheaper to simply make the dedicated power circuits needing DMX control into a Sensor rack with relays. Sensor is very, very easy to wire up. (Edit: - SmartSwitch does allow for 2 pole circuits, which Sensor does not).

The IGBT systems, as well as standard raceways that offer built in Ethernet or DMX, have to pay close attention to providing for separation within the enclosure of the lo-vo section with the 120v. Combing Lo and Hi voltage in raceways, while seemingly desirable, forces you to think about the robustness of the data cable running/bundled alongside the 120v multi. This is less an issue when the raceway isn't flying - catwalks, etc... where you can specify off-the-shelf Cat5 receptacle panels somewhere convenient to the devices needing data. You still need to do some thinking about data to moving positions that use Soca for dimmed distro, or that are getting dedicated power. Many questions in my mind as to how to do this well.

I'm currently toying with the idea of not overloading on racked dimmers, especially at positions that will see occasional use, but simply putting in a lot of dedicated power off Sensor relays, as well as lots of local data ports, then buying a whole bunch of BakPaks or Leprecon 4 way dimmer packs. Then the circuits can be ML power, OR power to a dimmer pack for conventionals. An example is a series of 19 balcony rail positions that can handle 3-4 conventionals, OR maybe 1-2 ML's, ea. Rather then put in 4 circuits @ 2.4kw dimmed, I'll install 2 @ 2.4kw as relay. Thus I have ML power for easily 4 fixtures @ up to 700 watt lamp types, OR a Leprecon 4 pack that can run on 2 circuits and provide for 4 x 900w dimmed circuits. Do I need 208v ML fixtures here, probably not. 

In any event, I wish ETC still made the old LMI quad 1.2kw dimming rack that had (if memory serves) 192x1.2 dimmers in a rack. Put that in a Sensor and I'd spec. it in a minute. Trouble I see is a re-design would be required to fit 192 lugs for branch circuits, not to mention more space needed for the chokes. Or maybe a cheap Sinewave @ 1.2kw ?. 

Steve B.


----------



## STEVETERRY (Oct 11, 2008)

Van said:


> Wow There have been a lot of great posts in this thread! Some really great info and opinions. A lot of the variables have been discussed very well. As you can get almost any dimmer package in almost any arrangement; you can get as many data drops and power feeds as you are willing to pay for or can afford, or that your facility will support, I feel a lot of the choice comes down to whether you're a Mac or PC kind of person. I have a deep seated love for IBGT dimmers, I don't like Macs, But I feel IBGTs are sort of the Mac of dimmers. They're a bit more expensive initially, but you simply can't beat them for safety. They have more compatibility across the board like PCs do but they have a much better "Plug and Play" capability. Need to run a motor? Balasted light source? Incandescent? Just plug it inand turn it on. Try that with an SCR.



Sorry, but I don't agree with your view about an IGBT dimmer dealing well with many different load types. History proves differently.

The ET IGBT dimmer operates in either forward or reverse phase control mode. A load with any inductive component cannot be used with reverse phase control. Either you manually force the dimmer into forward phase control mode for such a load, or you rely on the dimmer's internal sensing of the inductive load to automatically switch to forward phase control. This does not always work perfectly, in my experience. The result can be a failure.

Now a well designed _sine wave _dimmer that uses IGBT's as the power devices is a different story. That type of dimmer has wide tolerance of a lot of "odd loads".

In fact, SCR dimmers are quite tolerant of many types of resistive, inductive, and capacitive loads.

As your your "safety" comment--please elaborate, since right now I see no basis in fact or history behind that statement.

ST


----------



## Van (Oct 12, 2008)

STEVETERRY said:


> Sorry, but I don't agree with your view about an IGBT dimmer dealing well with many different load types. History proves differently.
> 
> The ET IGBT dimmer operates in either forward or reverse phase control mode. A load with any inductive component cannot be used with reverse phase control. Either you manually force the dimmer into forward phase control mode for such a load, or you rely on the dimmer's internal sensing of the inductive load to automatically switch to forward phase control. This does not always work perfectly, in my experience. The result can be a failure.
> 
> ...


 
I have never NEVER had a failure, nor have I heard of a case in which an ET IPS dimmer failed to correctly identify a load type. While you can run an inductive or capacitive load on an SCR based dimmer you must needs have a dedicated dimmer type to do so. 

Safety? IGBT dimmers will "clamp" to a dead short faster than a circuit breaker, and that ability is not diminished over time by corrosion, and it doesn't get "loose" like a breaker either. I think the safety issue is rather self evident.


----------



## STEVETERRY (Oct 12, 2008)

Van said:


> I have never NEVER had a failure, nor have I heard of a case in which an ET IPS dimmer failed to correctly identify a load type. While you can run an inductive or capacitive load on an SCR based dimmer you must needs have a dedicated dimmer type to do so.
> 
> Safety? IGBT dimmers will "clamp" to a dead short faster than a circuit breaker, and that ability is not diminished over time by corrosion, and it doesn't get "loose" like a breaker either. I think the safety issue is rather self evident.



I'm glad to hear you have never had a failure--that's a great endorsement! Others have not had the same experience, however.

Electronic short circuit protection is a requirement of an IGBT dimmer due to the relative fragility of the power device itself in the presence of a short circuit. A circuit breaker cannot act fast enough to protect the IGBT. This speed, however, does not translate into "safer".

In fact, UL does not accept electronic short circuit protection as the only overcurrent device--they require an upstream breaker or fuse. In the case of the product we are discussing, that is a standard thermal/magnetic breaker in a panel. That breaker is only rated for 80% continuous loading rather than the 100% of a typical fully-magnetic breaker on a professional dimmer rack.

This raises another compromise: the raceway system has two 2.4kW dimmers fed from single 20A feed, so the maximum aggregate load across the two dimmers is advertised as 2.4 kW. In reality, if this system is fed from a 20A thermal/magnetic breaker in a panelboard, the aggregate maximum load across the two dimmers is only 1920W continuous, due to the inherent 80% rating of the breaker. 

That means that two adjacent dimmers cannot support 2 x 575W continuous loads each, when both dimmers are on. This may be too much of a derating compromise for some users.

Finally, there has been some discussion here about heat. The heat load of the distributed dimmer is insignificant compared to the heat load of the lamp it is driving. So, we don't need to worry about bigger air conditioning in a space for distributed dimmers.

However, the sensitivity of an IGBT convection-cooled dimmer to increased ambient temperatures in much greater than that of a rack SCR dimmer. The product we are discussing deals with that by reducing its rise time (or fall time when operating in reverse phase control mode). That means than an advertised rise time of 500 or 800 microseconds may be considerably less than that when the dimmer is fully loaded and operating in elevated ambient temperatures caused by being in close proximity to lots of hot lights. That means noisier filaments under those conditions, another compromise that potential purchasers need to be aware of.

ST


----------



## SteveB (Oct 12, 2008)

STEVETERRY said:


> This raises another compromise: the raceway system has two 2.4kW dimmers fed from single 20A feed, so the maximum aggregate load across the two dimmers is advertised as 2.4 kW. In reality, if this system is fed from a 20A thermal/magnetic breaker in a panelboard, the aggregate maximum load across the two dimmers is only 1920W continuous, due to the inherent 80% rating of the breaker.
> ST



Steve, 2 comments/questions:

1) If I understand the ITS literature correctly, you feed 3 - 2.4kw dimmers with a single 20amp, 3 pole breaker (3 hots, 1 neutral). On the raceway series, you can split loads across a 2.4kw, to be 2 dimmed circuits, loading either side as desired, up to the max. capacity of the single non-split dimmer. The dimmer strips and packs need to be pre-selected and purchased as either 3x2.4kw dimmers or 6x1.2kw dimmers, which are still fed via 1-20amp, 3 pole panel breaker per every 3 or 6 dimmers. The raceway design is seemingly advantageous if the load is expected to be individual fixtures per dimmer at 575 or 750 watts, as you can load up 96 fixtures, each on individual dimmers on a 96ft. raceway, or whatever length is appropriate. In this case the de-rating of the panel breakers is an issue for 1kw loads, but not for lesser loads, which in my mind is a good reason to throw out all those old 1kw PAR64's for ETC S4 Pars (grin). 

2) Are standard panel mount industrial type breakers (as opposed to the typical breaker on Sensor dimmer or relay), available as 100 percent continuous loading ?. This de-rating due to distro. panel requirements can be a deal breaker in some cases, IMO.

3) If the desire, and the ETC Load Survey seems to support this, is individual fixtures @ 575w, 750w, but NOT 1000w loads, ea. on individual dimmers, then the ITS IGBT system is attractive to a system designer/end user. All things being equal, I could see recommending this design if the architecture supported fixtures in this wattage size(s), such as FOH coves or catwalks, where the flexibility of having 2.4kw circuits is not required (I cannot fit a 2kw fixture in my coves, as example). 

Just some food for thought.

Steve Bailey
Brooklyn College


----------



## STEVETERRY (Oct 12, 2008)

SteveB said:


> Steve, 2 comments/questions:
> 
> 1) If I understand the ITS literature correctly, you feed 3 - 2.4kw dimmers with a single 20amp, 3 pole breaker (3 hots, 1 neutral). On the raceway series, you can split loads across a 2.4kw, to be 2 dimmed circuits, loading either side as desired, up to the max. capacity of the single non-split dimmer. The dimmer strips and packs need to be pre-selected and purchased as either 3x2.4kw dimmers or 6x1.2kw dimmers, which are still fed via 1-20amp, 3 pole panel breaker per every 3 or 6 dimmers. The raceway design is seemingly advantageous if the load is expected to be individual fixtures per dimmer at 575 or 750 watts, as you can load up 96 fixtures, each on individual dimmers on a 96ft. raceway, or whatever length is appropriate. In this case the de-rating of the panel breakers is an issue for 1kw loads, but not for lesser loads, which in my mind is a good reason to throw out all those old 1kw PAR64's for ETC S4 Pars (grin).
> 
> ...



1. My understanding is that in the raceway system 6 x 2.4 kW are fed from a 3-phase 20A feed. Any one dimmer can be loaded to 2.4kw, but pairs can only be loaded to 2.4kW total.

2. While there are 100% electronic-trip breakers available, I am not aware of any at the 20A level.

3. I like derating as much as the next guy--but I want to choose where to derate. If we are accepting 1.2kW dimmers for a good reason--like less expensive sine wave dimmers where absolute silence is required--fine. But if we're dropping the power on a non-sine-wave dimmer, given that a 1.2kW SCR dimmer costs the same as a 2.4kW SCR dimmer--I can't see the logic.

I want to be able to put 2.4kW loads wherever I want--as long as I'm not compromising for the quiet of cost-reduced sine wave dimmers.

Let's remember that the noise performance of an IGBT dimmer operating in forward phase control mode is identical to that of the equivalent rise-time SCR dimmer. And the noise performance of a reverse phase control IGBT dimmer is not equivalent to a sine wave dimmer.

ST


----------



## SteveB (Oct 13, 2008)

ST Wrote:

"1. My understanding is that in the raceway system 6 x 2.4 kW are fed from a 3-phase 20A feed. Any one dimmer can be loaded to 2.4kw, but pairs can only be loaded to 2.4kW total."

Well THAT makes no sense !. On a system where I might spec. 32x2.4KW Sensor circuits, they would put in a raceway with 32x2.4kw IGBT's (that "Or Approved Equal" clause), but only provide power to load ea. dimmer at 50%, or have 64 split dimmers at 1.2kw, but really ony 600 watts ea. Maybe I'm not getting it, but I would be very un-happy with that design.

A very preliminary design for our new building showed the renovated theater as having 2 dimmer racks - presumably the typical 96x2.4kw rack(s), ea. fused at 400 amps, 3 phase, per rack. I've been down this road before, and won the last time, when I pointed out that sizing the feeds and main breaker at this rating essentially down rates ea. 2.4kw dimmer by approx. 30% or so, or basically ea. dimmer becomes a 1.8kw. I believe it was ST who recommended to me (advise we followed) to fuse at 600 amps per rack, with 800 total for 2 racks, so at least we could load up a "zone" of the theater if needed. Steve, I believe you wrote a trade journal article about this subject a few years (decades ?) ago.

Which brings up the question - All is fine and well when you have a Sensor 48, with 96x2.4kw dimmers, all rated at 100% continuous load, but is the main breaker, be it a 600 or 800 3 pole, now downrated by 20% ?. If that's the case, I would and can make the case that all racks shall be fed from 600 amp main breakers. 

"3. I like derating as much as the next guy--but I want to choose where to derate. If we are accepting 1.2kW dimmers for a good reason--like less expensive sine wave dimmers where absolute silence is required--fine. But if we're dropping the power on a non-sine-wave dimmer, given that a 1.2kW SCR dimmer costs the same as a 2.4kW SCR dimmer--I can't see the logic."

I could see the logic if we were following the implications of the load survey, and stopped using 2.4kw circuits in a lot of places that don't need them, then could save on wiring costs by running #14 wire, instead of #10. If it were a rack with 192 x 1.2kw dimmers in the space of a 96x2.4, then when combined with the smaller wiring, the costs come down a lot. Trouble is, I doubt the New York City electrical (or Nat'l Code for that matter) would allow me to run 10 amp branch circuits for stage lighting, as I believe 20 amps is the minimum.

But a thanks to ST for some very informative comments and as usual I learned a bunch.

Steve B.


----------



## STEVETERRY (Oct 13, 2008)

SteveB said:


> ST Wrote:
> 
> "1. My understanding is that in the raceway system 6 x 2.4 kW are fed from a 3-phase 20A feed. Any one dimmer can be loaded to 2.4kw, but pairs can only be loaded to 2.4kW total."
> 
> ...




A main breaker is a thermal/magnetic device rated at 80% continuous load, unless it is specified as a 100%-rated electronic-trip breaker.

On a two-rack system, I would buss them together and feed from a single 800A breaker.

ST


----------



## derekleffew (Oct 13, 2008)

SteveB said:


> ... I believe it was ST who recommended to me (advise we followed) to fuse at 600 amps per rack, with 800 total for 2 racks, so at least we could load up a "zone" of the theater if needed. Steve, I believe you wrote a trade journal article about this subject a few years (decades ?) ago.


Summer 2002, in the ESTA quarterly, _Protocol_. See attached. Any revisions you would make today, Mr. Terry?


SteveB said:


> ...As other have pointed out, there are many ML's wanting 208v, though I question as to the application of the larger and brighter ML's that need 208, being needed in smaller spaces. You still need "some" 208 around, so best plan for it, but I have a question - are the fixtures needing 208, using 208 only because they are brighter ?, or is the feature set of the larger fixtures what people are after ?...


Not just because they are brighter, although that's a prime reason. Just as because of the CompactDisc, audiences demand hifi sound; seemingly more onstage lumens are required for each production. We're talking theatre, and theatre requires hard edge fixtures with shutters, right? So the choices are Revolution or VL1000T in the incandescent range; and VL1000A, MAC2000Performance (120V or 208V) or VL3500SPOT (208V only).


----------



## STEVETERRY (Oct 13, 2008)

derekleffew said:


> Summer 2002, in the ESTA quarterly, _Protocol_. See attached. Any revisions you would make today, Mr. Terry?



Only that it is probably somewhat extravagant to use a full size main breaker on _each_ rack fed by a de-rated main. A much more economical approach is to use _factory-bussed racks_ and a single de-rated main breaker. You lose the advantage of a separate disconnect for each rack and the associated fault propagation control, but it sure gains you a lot of dollars in switchgear and labor to go with the bussed system. And it changes nothing in terms of your derating philosophy.


In addition, the recently-available Harmonic Mitigating Transformer (HMT) is a preferable option to a K-rated transformer for feeding a phase-control dimming system. See Transformer, Harmonic Mitigating in the Glossary for details.

ST


----------



## SteveB (Oct 13, 2008)

STEVETERRY said:


> Only that it is probably somewhat extravagant to use a full size main breaker on _each_ rack fed by a de-rated main. A much more economical approach is to use _factory-bussed racks_ and a single de-rated main breaker. You lose the advantage of a separate disconnect for each rack and the associated fault propagation control, but it sure gains you a lot of dollars in switchgear and labor to go with the bussed system. And it changes nothing in terms of your derating philosophy.
> 
> 
> In addition, the recently-available Harmonic Mitigating Transformer (HMT) is a preferable option to a K-rated transformer for feeding a phase-control dimming system. See Transformer, Harmonic Mitigating in the Glossary for details.
> ...



Can you say "Cut and paste" ?. 

Actually, I was just writing the section as to how the transformers planned should be K rated, which is now HMT

I'm sure the consultant is now going to have to do some research - What the hell is a "Harmonic Mitigating Transformer" ?. (grin),

So a big Thank You.

SB


----------



## STEVETERRY (Oct 13, 2008)

SteveB said:


> Can you say "Cut and paste" ?.
> 
> Actually, I was just writing the section as to how the transformers planned should be K rated, which is now HMT
> 
> ...



Tell him to look at the websites for Powersmiths: Powersmiths - Power for the Future or Mirus: Mirus Harmony Transformers.

You can also send him a copy of my "New Power Tools" article on the subject, which has a link in the glossary entry: http://www.controlbooth.com/forums/glossarys/9011-transformer-harmonic-mitigating.html.

ST

Edit by DL: See also the articles referenced in the glossary entry: Harmonics.


----------



## derekleffew (Feb 11, 2009)

Not intending to open any healed wounds, but felt the following from a non-partisan individual on the Light Network might be pertinent, and beneficial to the discussion:


> As an early experimenter in FET and IGBT dimming, there are some problems that need
> to be understood. These are problems that usually don't affect theatrical style lighting.
> They can be a problem for fllash and dash. Mind you, these are all problems that confront
> normal SCR dimming; we've just gotten away with them.
> ...


----------



## SteveB (Feb 11, 2009)

What I found especially amusing is that one of the selling points for IGBT is that they provide "Dead Short Protection". What they don't tell you is that the circuit HAS to have Dead Short Protection.

Kind of like Airbus making a selling point of how well their airplanes float.

SB


----------



## STEVETERRY (Feb 11, 2009)

SteveB said:


> What I found especially amusing is that one of the selling points for IGBT is that they provide "Dead Short Protection". What they don't tell you is that the circuit HAS to have Dead Short Protection.
> 
> Kind of like Airbus making a selling point of how well their airplanes float.
> 
> SB



Want a job in ETC marketing? 



ST


----------



## SteveB (Feb 11, 2009)

STEVETERRY said:


> Want a job in ETC marketing?
> 
> 
> 
> ST



Sure, but you're gonna have to put up with endless questions like "When does the temperature go above -20" and "Where's the ocean ". 



SB


----------



## derekleffew (Feb 11, 2009)

SteveB and SteveT could carpool/[-]planepool?[/-]/share the corporate Gulfstream jet.


----------



## SteveB (Feb 12, 2009)

derekleffew said:


> SteveB and SteveT could carpool/[-]planepool?[/-]/share the corporate Gulfstream jet.



Yeah, and those Fred F paid-for junkets to Florida and the Bahamas, that all the senior ETC VP's take advantage of regularly.

From company e-mail "The jet for Fridays meeting on the Ion Jr. will be leaving at 7AM SHARP". 

SB


----------

