pitchshifter Posted February 18, 2007 Share Posted February 18, 2007 Hi there...My auditorium is in a University and the electrical current at some times of the day(normally 9:30am, 11:30am, 18:30pm) has harmonics...Those harmonics cause a strange behavior in my dimmers... a random projector connected to one of the dimmers starts to flash for 2 minutes! We have tried lots of different ways of approach but unsuccessful... The light network is composed by 4 dimmers (6 outputs each) and the projectors are normal theater pc's The dimmer is a ies pr-6 mounted... Recently someone told me that if I changed the dimmer curve it may stop happening but I didn't had luck so far... If this is correct witch dimmer curve is the best to use? the S curve? Can anyone help me solving this? Thanks Link to comment Share on other sites More sharing options...
David A Posted February 18, 2007 Share Posted February 18, 2007 There is no logical way for the change of curve to effect the interference.A common way to absorb this is to put a .1 microfarad capacitor across the 240v side of the control transformer. I once had a similar situation with a triac which had a sensitive gate, but that was a rare case. Link to comment Share on other sites More sharing options...
david.elsbury Posted February 18, 2007 Share Posted February 18, 2007 .. a 0.1 microfarad capacitor...Make sure this capacitor is suitably mains rated else bad things will happen! Have you considered getting an electrician in to have a look at the problem? Link to comment Share on other sites More sharing options...
David A Posted February 18, 2007 Share Posted February 18, 2007 The probability of the fault being in the wiring system is extremely remote so bringing an electrician in is probably a waste of money and having electricians working on dimmers is frequently a disaster, so if you're not competent to do it find an electronics technician to look at it for you. Link to comment Share on other sites More sharing options...
zonino Posted February 18, 2007 Share Posted February 18, 2007 chances are the university will have its own electrical services department, therefore electrician will cost a grand total of £0.00 and from those times, its when the load on the system changes dramatically... 9.30 - lots of PC's etc get turned on11.30 - kitchens and eaterys turn up the heat around the campus18:30 - lots of PC's etc get switched off (my reasons may be slightly off, but I've experienced these sort of voltage problems at similar times when doing all-day get ins at the uni, didn't affect our dimmers fortunately) Link to comment Share on other sites More sharing options...
David Duffy Posted February 18, 2007 Share Posted February 18, 2007 Hi there...My auditorium is in a University and the electrical current at some times of the day(normally 9:30am, 11:30am, 18:30pm) has harmonics...Those harmonics cause a strange behavior in my dimmers... a random projector connected to one of the dimmers starts to flash for 2 minutes! We have tried lots of different ways of approach but unsuccessful... The light network is composed by 4 dimmers (6 outputs each) and the projectors are normal theater pc'sI'm not sure exactly what you're referring to when you say "harmonics". Is this something you can hear (as tones) through the PA as well? If so, you may be having trouble with off-peak electricity control tones that are imposed on the mains. (I'm assuming Australia is not the only one to use this system) These tones can get into the phase control (zero crossing) section of (mainly cheap) dimmers and cause all sorts of level related faults. They generally are present either side of peak electricity demand times to turn hot water services off during thise peaks. (Breakfast, lunch and dinner, etc) It may have no bearing on your problem but it's worth thinking about anyway. Link to comment Share on other sites More sharing options...
Tomo Posted February 18, 2007 Share Posted February 18, 2007 Have you tried calling the dimmer manufacturer's support number?Or failing that, the local dealer for them? Assuming that you've already tested the DMX at the dimmers, then the manufacturer or service centre may have newer software that fixes the problem, or can adjust parameters inside the dimmer to allow for these 'harmonics'. Either way, a local spark or general electronic engineer is unlikely to be able to help! Link to comment Share on other sites More sharing options...
kalmatthew Posted February 18, 2007 Share Posted February 18, 2007 <snip> a random projector connected to one of the dimmers starts to flash for 2 minutes! </snip> do any of your other lights do this? Its not normally the best idea to dim projectors anyway! Link to comment Share on other sites More sharing options...
Sarah Q Posted February 18, 2007 Share Posted February 18, 2007 In addition to the OP's question, there have been an interesting thread recently regarding harmonics on the Electrical & Power board... http://www.blue-room.org.uk/index.php?show...w=&st=& I had never even heard of harmonics before reading this.... must admit it made my brain ache though trying to get my head around it all Link to comment Share on other sites More sharing options...
david.elsbury Posted February 18, 2007 Share Posted February 18, 2007 <snip> a random projector connected to one of the dimmers starts to flash for 2 minutes! </snip>do any of your other lights do this? Its not normally the best idea to dim projectors anyway!For "projector" read lamp/light/luminaire/instrument/fixtureand the projectors are normal theater pc's:) Link to comment Share on other sites More sharing options...
kalmatthew Posted February 18, 2007 Share Posted February 18, 2007 <snip> a random projector connected to one of the dimmers starts to flash for 2 minutes! </snip>do any of your other lights do this? Its not normally the best idea to dim projectors anyway!For "projector" read lamp/light/luminaire/instrument/fixtureand the projectors are normal theater pc's:) I didnt spot that oops, I must read posts more carefully Link to comment Share on other sites More sharing options...
Brian Posted February 18, 2007 Share Posted February 18, 2007 In case people haven't spotted it - the OP is in Portugal. Link to comment Share on other sites More sharing options...
JimWebber Posted February 19, 2007 Share Posted February 19, 2007 Hello, I personally would try to eliminate dimmer and/or DMX problems before looking too hard at supply issues... Does the projector/lantern flicker when connected to any other dimmer channel? I would also check that the DMX line is terminated and free from interference. Just a thought! Jim Link to comment Share on other sites More sharing options...
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