Do we really need 2.5Kw dimmers?

[Neil Frazer]

ETC have just completed a survey in to Dimmer Loading.

 

The results of which are Here

 

These results interestingly show that over 50% of the dimmer channels in use (outside America) do not have more that 1.2Kw of Load.

 

Obviously there are occasions where 2.5K is needed and 5K for that matter but as new technology is now becoming available would it not make sense to start looking at smaller dimmer capacities saving costs in equipment and also associated install items, Cable sizes, feeders etc.

[Guest mattladkinlx]

Personally I feel that for larger venues, a selection of 1.2kw, 2.5kw, 5kw and 10kw channels are needed so yes 1.2kw dimmers would be useful. Certainly as the trend is to go for a majority of 575, 600, 750 and 800w lamps in your rig then it makes sense to reduce dimmer sizes (or for plug and play dimmers, to offer a dual 1.2kw dimmer for every 2.5kw dimmer bay).

 

However for smaller venues where lanterns are often paired on a dimmer then no, a 2.5kw channel is needed. (this venue however does not need 5kw or 10kw dimmers!)

 

Well thats my thoughts on the matter! :)

[Dmills]

Personally I feel that for larger venues, a selection of 1.2kw, 2.5kw, 5kw and 10kw channels are needed so yes 1.2kw dimmers would be useful. Certainly as the trend is to go for a majority of 575, 600, 750 and 800w lamps in your rig then it makes sense to reduce dimmer sizes (or for plug and play dimmers, to offer a dual 1.2kw dimmer for every 2.5kw dimmer bay).

 

However for smaller venues where lanterns are often paired on a dimmer then no, a 2.5kw channel is needed. (this venue however does not need 5kw or 10kw dimmers!)

 

Well thats my thoughts on the matter! :)

 

In a mostly profile world 1.2Kw is probably adequate, however most shows in this country use an extensive collection of Fresnel lanterns which are still typically 1.2KW, being able to pair these is useful.

 

I would note that the cost difference between a 5 amp dimmer and a 10 amp one is almost certainly smaller then that cost differential between a 10A and a 20A example. In the US market a 2.4Kw dimmer is a 20A device whereas here it is a 10A one. Thus there may be considerably less margin in installing 1.2K racks in 230V land then there is in doing the same in the 'states.

 

Assuming we are still talking thyristor racks, I really don't see any margin in going to a 5A rating, there might be slightly more margin in this with things like IGBT or sine wave dimming where the semiconductors are a little more expensive, but even there the differential will be much smaller then it would be in a 120V country.

 

As for the argument that it would reduce the size of the feeders required, how so? The dimmer is not the load, the lanterns are the load, and you have already made savings there by moving to modern profiles!

 

Now if you could get 4 * 1.2Kw circuits in the same space as a dual 2.4 then there might be some margin in it, but even there the real cost of installing a rack is probably in the final circuit wiring, not in the power modules, in any case these would have be be interchangeable with a dual 2.4 for when the heavy load is required which means the module would have to have its output circuits terminated to a patch on the front panel (Weiland??).

 

Just my �£0.05.

 

Regards, Dan.

[Bryson]

Admittedly, in my space, 90% of the rig is 1.2k or less....but...I wouldn't want to try and fit up the turnover I have right now with the extra challenge of only having a few channels into which I can grelco stuff.

 

For me, having 10a dimmers is about having the flexibility to pair or use a 2k when and whereever I want to, without making extra preparations.

 

Obviously for long-running shows, or semi-permanent installs, correctly sizing the dimmers is the way forward, but for venues in weekly rep or turning over one-nighters, you need all the flexibility you can get.

[woody74]

Obviously for long-running shows, or semi-permanent installs, correctly sizing the dimmers is the way forward, but for venues in weekly rep or turning over one-nighters, you need all the flexibility you can get.

 

Couldn't agree more. In my job, we have all 2.4k dims, and we max them out sometimes, but mostly we run around 10a per. And for thiose shows where we need to max it out, it would cost a whole lot more to have to hire dimming and feeder. Spend on the front end so you don't get hit with unexpected costs (that you may not be able to cover) on the back end.

 

One thing we run into is line loss, since our dimmers are central and the farthest room is over 60m away. With a circuit that would normaly pull 19a at full capacity, with the loss we end up pulling about 22a.

 

-w

[Dmills]

Obviously for long-running shows, or semi-permanent installs, correctly sizing the dimmers is the way forward, but for venues in weekly rep or turning over one-nighters, you need all the flexibility you can get.

 

Couldn't agree more. In my job, we have all 2.4k dims, and we max them out sometimes, but mostly we run around 10a per. And for thiose shows where we need to max it out, it would cost a whole lot more to have to hire dimming and feeder. Spend on the front end so you don't get hit with unexpected costs (that you may not be able to cover) on the back end.

 

Ahh someone in 120V land I see.

 

One thing we run into is line loss, since our dimmers are central and the farthest room is over 60m away. With a circuit that would normaly pull 19a at full capacity, with the loss we end up pulling about 22a.

-w

 

The tradeoff may be slightly different over there where a 2.4K load is 20 amps (And where loosing 5v to cable resistance matters more then it does here), For the same percentage loss to heating up the wiring you need 4* the cross section of cable, ouch (My back hates the thought of 120V, give me 230/400 any day)!

I suspect that this means that far more of your cables are sized by voltage drop considerations (as opposed to being thermally limited).

 

Your 19/22A statement implies a constant power load (switched mode power supply or induction motor), not something I would normally think to dim!

 

Regards, Dan.

[woody74]

:) See what happens when one goes shooting one's mouth off before doing the math...

 

Nevertheless, I would err on the side of too much vs. not enough.

 

-w

[niclights]

I run nearly all my dimmer channels at 2kW, some at full 2.5kW. Obviously smaller capacity dimmers have their place as do the larger ones, but in my experience in rock'n'roll world I often find 1kW pars paired.

[mac.calder]

Australia naturally uses 10A circuits - our GPO's are 10A, and so it seems natural that 10A is the standard for dimming. I think you would be hard pressed to find 5A channels on dimmers here. Most venues I have seen have usually had a few 20A channels as well.

 

Since 40A three phase is the standard three phase outlet you find now in Australia, 12 x 10A circuits makes a lot of sense. That said, I borrowed 2 touring packs the other day which were 6 x 10A (Which is a waste imo).

 

I know that I often underload dimmers (quite often having only 1 lantern on a channel) however the 2k4 just makes sense. If I have a 2k light, I don't have to worry about making sure I plug in a larger dimming module or worrying that I will not have enough 2k4 channels. If I am using 1k lanterns, I can pair them with little to no worry, and if I am using 500W/600W lanterns, I can put four on a channel. Basically, the 10A number just works. There is no "Sorry, you can't plug that lantern in there because that is a 1k2 channel, and that is a 2k lantern".

 

If I was desiging a venue where there would be 1:1 hard patching between the stage and dimmers, I would automatically put 10A per outlet, maybe 20A on the extream sides of each bar and on the rear bar. I would not even consider 5A.

[WiLL]

Less power?? LESS POWER!!?? You want less power and you call yourself a technician??!! :unsure: Nooooooooo! I like being able to put a pair of parcans on one channel. I run a fairly large space and only have 48 dimmer channels. I'd be happy with 10k dimmers, providing I didn't have to pay for them of course :)

[dirkenstein]

How about headroom?

It makes me nervous putting 1K parcans on 5A dimmers simply because I know I'm close to the rated maximum current- sure the breaker or fuse will go on a short or on sustained overload, but it does seem surprisingly easy to kill triacs with surge overloads. And 2x650W (at 5.4A) may not blow a fuse before the triac gives up. Certainly I've seen a few betapack channels killled over time by the surge from injudicious plugging in of cold lanterns on channels that were fully up, although this may be a bad habit of the relatively low-rated triacs on old betapacks, rather than a common problem of all dimmers. Certainly we haven't ever blown up any of our minipack channels. Of course, we tend to use minipacks for 500W to 650W loads maximum. Maybe this is an overly conservative approach, but comparing the nuisance of having to repair blown electronics pre-production against the expense of 10A vs. 5A dimmers, the advantages just aren't there for us.

 

I tend to agree that the advantages of closely rated dimmers might be much higher for long-running shows where you can pare down equipment costs to the minimum needed to run just that show during the design.

[Neil Frazer]

Ok. just to clarify my position here.

 

I'm not saying that I agree with ETC's suggestions, I'm mealy putting it up for discussion...

 

One of the points they made was that the size of a 2.5Kw sine wave dimmer is about 4 times that of a 1.5Kw one and significantly more expensive.

I think what they are saying is that to make sine wave dimming a feasible alternative to thyristor dimming they need to consider 1.5K for the majority of circuits with 2.5K and above only where necessary.

 

I agree that pairing channels is a necessity at the moment for many situations but with 4x1.5K dimmers in the space of 1x2.5k would you still need to pair up?

 

 

Discuss... :)

[mac.calder]

It depends on the actual numbers, but I know that I would not really mind if the majority of them were 1k2's, however I would 'demand' at least a fair number (maybe 15-20%) be of higher value.

[OB2]

I know in my theatre we need 2.5kw dimmers, just because we are a very small studio theatre with very limted equipment thus, were pairing up all over the joint, we end up running all sorts through them, but if its a permant install with a fixed patch then you could probably get away with it happily but unfortunatly not in my world!!!!! :)

[Stu]

This is a very interesting topic!

 

In our theatre we have 218 ETC Sensor 3kw dimmers and 12 5kw dimmers, and I really can't think of a time where I have actually needed the headroom the 3kw dimmers provide - obviously for use with 2kw fresnels (we only have 4 mind), but for 95% of the time our dimmers are running at 1kw or less. Even the 2 biggest shows, dimming wise using in house kit, we have every year (panto for instance) I am hard pushed to think when I've needed more than 1kw on the majority of the dimmers.

 

I appreciate that in smaller venues (because I used to do the same myself!) that it's extremely handy to have 48 or 72 ways of 2.5kw dimming as the lack of dimmers makes pairing up in some instances a neccesity but in a venue like mine where I have so many dimmers to hand, pairing up is extremely rare - even then it's more likely to be pairing up practicals running at a max of 60w a time.

 

The 12 5kw dimmers do come in extremely handy for flood bars and groundrows (and the extremely rare occurance of a 5kw frensel) as it means I can just run 2 bits of soca off the bar and into the dimmers, but this is the only common and frequent pairing.

 

TBH, even if the dimmers on the fly floors and stage stay at 2.5kw/3kw, the ones FOH could certain all be 1kw/1.2kw as our fixed rig compromising of Cantata 11/26s, S4 19 750w and Par 64s all on seperate circuits - this is one area you could save money on perhaps, especially on new builds/installs where everyone is likely to be using S4s for FOH rigs. Checking back over old lighting plans while board oping tonight only shows 2 instances of using 2kw frensels FOH in the last year, and even then it was 1 or 2 right by the Pros so would be very easy to run them from the stage / fly floor dimmers.

 

The moving on to our concert hall, which has a fixed rig of S4 Pars, S4 10s (both at 750w), SL 15/32s and Par 64s it'd be even easier to make all the dimmers 1kw/1.2kw as the rig never changes!

 

It's certainly interesting to read everyone else's views and opinions on this....

 

Stu