TomLyall Posted March 18, 2004 Share Posted March 18, 2004 hmm, just sitting at my comptuer pondering over my english essay, I noticed all the lights in the house suddenly get, well, noticeably dimmer (noticeable enough to make me look up from my enthrawling essay that is). presumably this is because of a lack of power somewhere (someone down the road just turned on a 2 mW kettle I guess). <_< anyway to the point, does this kinda thing effect stage lighting too, (sounds too obvious doesnt it!?) and if so, do we have any protection against it? has it happened to you? I really cant imagine it would be great to have that in the middle of a really dramatic finale... ;) Link to comment Share on other sites More sharing options...
Andrew C Posted March 18, 2004 Share Posted March 18, 2004 Must say they're going to have a damned long wait for their tea!! And yes it does happen. We had a HVAC install done a few years ago. Basic extract / re-circ air handling with some heating elements to take the chill of the fresh air intake in the winter. The designer really screwed the control side, using thyristors rather that Triacs. This resulted in a nasty flickering as the heaters neared their target temp. Not too easy to see, but once you spot it, hugely irritating. As a general solution for your issue, probably not practical, you would need a UPS the size of your local supermarket I suppose! The BBC types probably have some sort of smoothing on their systems, but they have our licence fees to invest. ;) Link to comment Share on other sites More sharing options...
Ketil B Posted March 18, 2004 Share Posted March 18, 2004 hmm, just sitting at my comptuer pondering over my english essay, I noticed all the lights in the house suddenly get, well, noticeably dimmerthis is known as a brownouts and can be quiet common have a look hear for more info Link to comment Share on other sites More sharing options...
Mush Posted March 18, 2004 Share Posted March 18, 2004 heating elements to take the chill of the fresh air intake in the winter. The designer really screwed the control side, using thyristors rather that Triacs. This resulted in a nasty flickering as the heaters neared their target temp. Not too easy to see, but once you spot it, hugely irritating. Not sure how a triac would help, a triac behaves like reverse pair connected thyristors.AFAIK Triacs limit out at about 40 or 50A devices , SCR, thyristors go into kilo Amps. Guessing big air heater in hvac. Difference may be in operation , light dimmer chops each half cycle in phase angle control, heater contollers sometimes use burst fire control, letting through a few half cycles at a time. Link to comment Share on other sites More sharing options...
robloxley Posted March 20, 2004 Share Posted March 20, 2004 anyway to the point, does this kinda thing effect stage lighting too, (sounds too obvious doesnt it!?) and if so, do we have any protection against it? has it happened to you?We tend to find that it's more us flashing 200kW of theatre lights that affects the rest of the theatre (lights begin to flash in the bar...) and our neighbours (you can get the mains voltage to drop sufficiently for the car park lights to go out then have to re-strike, I hear...). I'd have thought a solution would be for big theatres to have their own mini-substation? Link to comment Share on other sites More sharing options...
david.elsbury Posted March 20, 2004 Share Posted March 20, 2004 At my show a few hours ago during one of the scenes, and again during the intermission, a few lights (a couple of 1ks and maybe 6 500w fresnels for the scene, and the cyc lights for the intermission) dipped off and then back on again. All of these are on the same dimmerpack. Our consensus was that there was a brown-out and that affected the dimmer- DMX and the board was fine. Anyway -david- Link to comment Share on other sites More sharing options...
Andrew C Posted March 20, 2004 Share Posted March 20, 2004 If these lanterns are on the same dimmer pack, check (or have checked) the mains connections on the input side NOW! I have seen just such dipping and it was caused by a loose neutral terminal. End result was a main breaker trip, an unexpected blackout and a very nasty smell. Link to comment Share on other sites More sharing options...
Andrew C Posted March 20, 2004 Share Posted March 20, 2004 Not sure how a triac would help, a triac behaves like reverse pair connected thyristors.AFAIK Difference may be in operation , light dimmer chops each half cycle in phase angle control, heater contollers sometimes use burst fire control, letting through a few half cycles at a time.Exactly the point. With a triac you switch both halves of the wave form at 0 crossing. The burst fire may also, or indeed, be the main cause of the problem. I'll look into this a bit further, thanks. Link to comment Share on other sites More sharing options...
P. Funk Posted March 20, 2004 Share Posted March 20, 2004 I'd have thought a solution would be for big theatres to have their own mini-substation?I know that the wycombe swan has something like that... so I'd imagine a lot of big theatres do as well... but then I suppose they need it if theyr'e drawing that much power. Link to comment Share on other sites More sharing options...
computer Posted March 20, 2004 Share Posted March 20, 2004 heh - be careful with those rigging mini DMX consoles you can get... you have to type in the channel you want. acidentally forgot to specify once and set the whole rig up to 100% in one go.... few minutes later, got a call on my mobile to go check the power room to see why the computers marketing/box office just restarted ;) Link to comment Share on other sites More sharing options...
david.elsbury Posted March 21, 2004 Share Posted March 21, 2004 check (or have checked) the mains connections on the input side NOW! ... (I have seen) it was caused by a loose neutral terminal.Erm... well yes I will try to. The dimmer in question is a Selecon PROpak (hideous, hideous piece of gear) and I know many other of the same model to have gone dodgy. I will get our tech representative (its an amdram grp) onto it soonish... the show ends next sat. And if it happens again I will open the dimmer myself. Thanks for that -david- Link to comment Share on other sites More sharing options...
Ellis Posted March 22, 2004 Share Posted March 22, 2004 I'd have thought a solution would be for big theatres to have their own mini-substation?The Birmingham Hippodrome has 2. Also, the West End has a mess of cabling (One 415V cable is connected to several substations if you would believe the suppliers records) Link to comment Share on other sites More sharing options...
Ike Posted March 22, 2004 Share Posted March 22, 2004 Here in Saddleworth (hilly with fairly dispersed housing/industry) it would seem that almost anyone who wants more than 100A gets there own transformer. Apparently it is quite common to have a single cable fed off multiple delta wye (delta star?) transformers. Link to comment Share on other sites More sharing options...
Pete McCrea Posted March 22, 2004 Share Posted March 22, 2004 If your at a festival using genies for the lighting supply you can rock them- stick all the lamps on and full then run the grand master up and down- better if you can see the genie, as you can time it so that the set rocks as it comes on and off load. Time it right and you can rock them over. Apparently...... Link to comment Share on other sites More sharing options...
Matt Posted March 23, 2004 Share Posted March 23, 2004 at the tech rehersal of our show this week, we managed to completely blitz a 200amp breaker in the main board for the school, god knows how, but all thel ights went out, the site manager had to drive all the way down to portsmouth to get a new one, from now on we wont use as many lights. the stupid thing was, we had done our calculations to each 6x10 amp pack being supplied with 32amps each, rather than 64 as it actually is :S Link to comment Share on other sites More sharing options...
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