Page 2 of 2 FirstFirst 12
Results 31 to 34 of 34

Thread: Workshop lighting suggestions

  1. #31
    aardvark
    Guest

    Re: Workshop lighting suggestions

    There are companies out there that trade on managing the lights for big operators like supermarkets, etc. They have a computer that dictates when to change the bulbs in a store before they start to fail all based on the type of usage, the number of times switched on and how long lit.
    Not sure I would want to do too much work for the likes of Tesco though. I bet they screw the price to the floor!!!

    Metal halide do not like being switched off and straight on again. They will take time to come back on. That is why a mixture of them and fluorescent is the current best solution.

  2. #32
    Footsfitter
    Guest

    Re: Workshop lighting suggestions

    Quote Originally Posted by Timbo_1975 View Post
    *most* new flouro's now have high frequency electronic ballasts now for this very reason, and should be insisted on where there are synchronous motors spinning.

    Sons, and MH and the like still flicker on/off at 50hz so be careful!

    A high wattage filament bulb will be much better as it doesnt actually go out each time the voltage changes direction cos of the thermal mass of the filament.

    Remember the Gunson strobeoscope...
    I always remember the Gunsons Colortune Plug......................



    ff



    .

  3. #33
    Footsfitter
    Guest

    Re: Workshop lighting suggestions

    Quote Originally Posted by RGSP View Post
    No, either you or your physics teacher has confused 90 degrees in phase with 90 degrees in position. The easiest and almost universal way of characterising AC waveforms is by their phase, where the instantaneous voltage (say) will be given by:
    V(inst) = V(peak) X cosine(theta)
    where theta is the phase angle. If you don't like sines and cosines, no worry, the key thing is that as this characteristic angle goes from 0 to 360 degrees it does through two peaks (when light will be at max), one positive at 90 degrees, and one negative at 270 degrees, and it will go through zero twice, once at 0 and once at 180 degrees, when the light output will go to zero.

    By using capacitors and inductors you can shift the phase of an ac power source, and it was common to operate fluorescents in pairs: one run from the unshifted mains, and one from a 90 degree shifted source, so that the peaks of light from one tube coincide with the dark points of the other, and vice versa.

    You have to order in such pairs specially, and to be honest I'm not sure whether you can still easily get them, because high frequency fluorescent fittings have mostly taken over, and have got to be only moderately expensive.

    D,

    Now thats not a bad reply for an Agricultural Forum

    ff




    .

  4. #34
    Exfarmer
    Guest

    Re: Workshop lighting suggestions

    Quote Originally Posted by RGSP View Post
    No, either you or your physics teacher has confused 90 degrees in phase with 90 degrees in position. The easiest and almost universal way of characterising AC waveforms is by their phase, where the instantaneous voltage (say) will be given by:
    V(inst) = V(peak) X cosine(theta)
    where theta is the phase angle. If you don't like sines and cosines, no worry, the key thing is that as this characteristic angle goes from 0 to 360 degrees it does through two peaks (when light will be at max), one positive at 90 degrees, and one negative at 270 degrees, and it will go through zero twice, once at 0 and once at 180 degrees, when the light output will go to zero.

    By using capacitors and inductors you can shift the phase of an ac power source, and it was common to operate fluorescents in pairs: one run from the unshifted mains, and one from a 90 degree shifted source, so that the peaks of light from one tube coincide with the dark points of the other, and vice versa.

    You have to order in such pairs specially, and to be honest I'm not sure whether you can still easily get them, because high frequency fluorescent fittings have mostly taken over, and have got to be only moderately expensive.
    This makes good sense and shows the danger of google
    I did a quick look at fluorescents and spinning rotors
    Several sites mentioned the dangers
    Some even decried it
    A few mentioned pairing tubes as they would cancel each other out
    But none explained why
    And the fact that they have to be paired in a specific way
    Simply having twin tube fittings or as many as you like has no benefit at all on the same circuit


    Highly deserving of a BFF Nobel prize me thinks
    Or at least a gold star

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •