grantr22 Posted March 15, 2014 Author Share Posted March 15, 2014 Thanks for all your input guys. Well the install was signed off yesterday so I've been in and had a play today. As I'd feared the LEDs are plugged in to dimmers which aren't set to hard power. This is convenient only if you want to take down the LEDs and put generics up as it means you can easily use the dimmer for what it's made for, but in standard rig form with the LEDs in place if you raise (from zero) or lower (from 100%) the affected faders or use the grand master, the dimmer channels with the LEDs connected trip out at the breakers. I think that's an added challenge that even the best of us could fall over mid-show even if we know we shouldn't ever adjust channels x y and z from 100%. I also now know what's happening to the 8 spare dimmer channels - nothing. They're not connected to anything and there's a label fixed to the panel to confirm this. Link to comment Share on other sites More sharing options...
top-cat Posted March 15, 2014 Share Posted March 15, 2014 I think that's an added challenge that even the best of us could fall over mid-show even if we know we shouldn't ever adjust channels x y and z from 100%. As I said, dependent on your desk you may be able to exclude certain dimmers from the grand master and DBO. Link to comment Share on other sites More sharing options...
Tomo Posted March 15, 2014 Share Posted March 15, 2014 It depends on your desk. I have some fixtures powered from dimmers running at 100%; in the desk I have the 'dimmers' set at 100%, not assigned to any kind of control, labelled clearly as non-dim, and set as exempt from DBO; and have no issues in this regard.Never do this! 100% from the console is not the same as "switched mode" in the dimmer.Most good-quality dimmers have soft starts, voltage regulation, top/bottom set or other features, which mean it may not always output a real full for a 100% DMX level input or zero for 0% DMX input. If you are powering 'hot power' devices that can accept 'dimmer in switched mode' then you must set that mode at the dimmer.This way the dimmer knows to enforce a "zero or full" rule, and turns off all the features aimed at other types of load. If you only do it at the console, your "100%" can often mean "90%" (or less) actual output, and thus may damage your devices. Aside from that, it's very important to check with the manufacturer of the devices to check that they can be powered from a dimmer (or solid-state switch), and use a physical relay or other 'hot power' if the manufacturer is unsure. (A solid-state-switch is not the same as a relay, no matter what marketing says!) Link to comment Share on other sites More sharing options...
top-cat Posted March 15, 2014 Share Posted March 15, 2014 It depends on your desk. I have some fixtures powered from dimmers running at 100%; in the desk I have the 'dimmers' set at 100%, not assigned to any kind of control, labelled clearly as non-dim, and set as exempt from DBO; and have no issues in this regard.Never do this! Unfortunately I am working on a show where I didn't design the power and so my options are live with it or turn half the rig off. The dimmers don't have a 'switched mode' else of course we'd do that. The power has been metered and the installer was happy that the power being received by the fixtures was suitable for them. Of course on my list of "Things we should really buy" is a couple of hot power distros to the same connections as the back of our dimmers, in equally sized rack units, so that we can swap them like for like. Until that day, it's play with fire or dance in the dark and I say that as if I have any sort of option in the matter anyway. My real point was not really whether or not it's a good idea to wire things this way; but only how you can minimise the chances of you fouling it up when other people have wired it this way and you are not in a position to actively change that. Link to comment Share on other sites More sharing options...
grantr22 Posted March 15, 2014 Author Share Posted March 15, 2014 As I said, dependent on your desk you may be able to exclude certain dimmers from the grand master and DBO. It's a Jester 24/48. Aside from that, it's very important to check with the manufacturer of the devices to check that they can be powered from a dimmer (or solid-state switch), and use a physical relay or other 'hot power' if the manufacturer is unsure. Yes, I was thinking I need to find out what the LEDs are and check with the manufacturer or distributor, though with the dimmers tripping out at about 90% fader suggests that the answer will be that they're not suitable to be powered from a dimmer. We have a show to do this week so I think I'm going to have to create a web of TRS from 13A sockets to each LED to get us through the week without any issues. Link to comment Share on other sites More sharing options...
ImagineerTom Posted March 15, 2014 Share Posted March 15, 2014 erm.... Shouldn't you (or the venue management) be getting in touch with the contractor/supplier for an explanation - at best the configuration will dramatically reduce the capabilities of the rig, much more likely is that it will cause a significant reduction in the lifespan of kit and compromise virtually every show that uses the theatre. The contractors must have planned for how this kit was going to be used and thus explain their procedure so that the system can be used OR if they haven't then they must be brought to task for fitting a system that isn't fit for purpose. Link to comment Share on other sites More sharing options...
grantr22 Posted March 15, 2014 Author Share Posted March 15, 2014 erm.... Shouldn't you (or the venue management) be getting in touch with the contractor/supplier for an explanation - at best the configuration will dramatically reduce the capabilities of the rig, much more likely is that it will cause a significant reduction in the lifespan of kit and compromise virtually every show that uses the theatre. The contractors must have planned for how this kit was going to be used and thus explain their procedure so that the system can be used OR if they haven't then they must be brought to task for fitting a system that isn't fit for purpose. Agreed, this will be my next course of action once I can back-up the cause with writing particularly the LED manufacturer's statement of suitability of them being powered from dimmers, and probably a similar statement from Anytronics. Link to comment Share on other sites More sharing options...
alistermorton Posted March 15, 2014 Share Posted March 15, 2014 The power has been metered and the installer was happy that the power being received by the fixtures was suitable for them. Did that include putting a 'scope on and checking the waveform? A meter tells you next to nothing about what's being delivered other than the average voltage. Link to comment Share on other sites More sharing options...
Brian Posted March 16, 2014 Share Posted March 16, 2014 Well the install was signed off yesterday... Excellent. That means all the information you need will be contained within the documentation that the contractor must have left as required by the wiring regulations. 132 DESIGN 132.1 General The electrical installation shall be designed to provide for:...b)the proper functioning of the electrical installation for the intended use. 132.13 Documentation for the electrical installation Every electrical installation shall be provided with appropriate documentation... Link to comment Share on other sites More sharing options...
grantr22 Posted March 17, 2014 Author Share Posted March 17, 2014 Thanks Brian I'll look into this. Link to comment Share on other sites More sharing options...
Ynot Posted March 17, 2014 Share Posted March 17, 2014 Agreed, this will be my next course of action once I can back-up the cause with writing particularly the LED manufacturer's statement of suitability of them being powered from dimmers, and probably a similar statement from Anytronics.Grant, I may be wrong (but don't think I am) but I seriously doubt that you'll find ANY low to medium (or even high) end budget LED kit that will be suitable for powering from a dimmer channel. And as has been pointed out, potentially not from a supposed 'switched' channel on many dimmers as many are NOT true hard-power switches. Get pukka hard power up to the LEDs however you can and that's the only way to do the job. Link to comment Share on other sites More sharing options...
timsabre Posted March 17, 2014 Share Posted March 17, 2014 Grant, I may be wrong (but don't think I am) but I seriously doubt that you'll find ANY low to medium (or even high) end budget LED kit that will be suitable for powering from a dimmer channel. It will be absolutely fine if you can lock the dimmer channel at 100% on the dimmer. Once the dimmer channel goes to anything other than 100% all bets are off and you can damage the fixture or the dimmer. Link to comment Share on other sites More sharing options...
david.elsbury Posted March 17, 2014 Share Posted March 17, 2014 But the waveform on your average dimmer is still chopped. .. not a pure sinewave surely? Therefore unsuitable for SMPS like in an led... Link to comment Share on other sites More sharing options...
Ynot Posted March 17, 2014 Share Posted March 17, 2014 Sorry, I don't think I was clear enough in my post (was a little late, admittedly). Referring to this bit: Yes, I was thinking I need to find out what the LEDs are and check with the manufacturer or distributor, though with the dimmers tripping out at about 90% fader suggests that the answer will be that they're not suitable to be powered from a dimmer. I really doubt any manufacturer is going to say that it's viable to power LED kit from anything other than proper hard-power for all the reasons given above - chopped waveforms, the risk of actually dimming the channel on some kit, etc. But I get the impression that you're actually trying to dim the fixture based on this comment - again, I could be wrong, but when you say 'dimmers tripping out at about 90% fader' that rings alarm bells with me. Link to comment Share on other sites More sharing options...
Brian Posted March 17, 2014 Share Posted March 17, 2014 Therefore unsuitable for SMPS like in an led... We're going a bit OT here (what's new?) but given that the first things most SMPSUs do is rectify the incoming waveform and smooth it out to an HV DC supply then the incoming waveshape doesn't matter*. As long as the average voltage exceeds the drop-out voltage of the supply then it will still produce the right output. *the caveat is that an incoming waveforms with a high HF content may cause issues with the input EMC filtering. **the other caveat is that we are assuming the LED unit has a SMPSU and not a transformer. Link to comment Share on other sites More sharing options...
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