32w PL HF Downlighters Unsuspectingly Dimming

[Steeley]

Hi, we desperately need help!!

We have installed a approximately 40no 32w high frequency PL Downlighters in a Gym, and it has come to light that when a supply fan on a AHU trips the lights in the gym start dimming over a period of around 5 mins, the lights loose around a third of there brightness.

Please note that these are not a dimmed ballast.

The voltage at the lights before and

after stays the same- 234 volts between line to neutral and earth.

The mechanical control panel which feeds the supply and extract fans is located in a store cupboard within the same gym as the lights, please see the scenario below. Voltage at control panel is 234 volts between all phases to neutral and earth.

Turn off main isolator to control panel- lights do not dim.

Turn off extract fan from 3 pole mcb within the control panel- the lights do not dim.

Turn off supply fan from 3 pole mcb within the control panel- the lights in the gym start to dim gradually.

Initially our thoughts were that the extract motor was inducing some form of harmonics down the line and consequently affecting the lights, this does not seem to be the case as we have swapped the motors and still have the same senario.

I don't think that the temperature within the gym is changing drastically to affect the ambient temperature around the lamps. The lamps are low amalgam. But can't rule this out.

The health club are now threatening to close the gym, but we simply don't have any answers.

You thoughts on this would be greatly appreciated.

Craig

 

[Doc Hudson]

Welcome to the forum, Have you tried contacting the manufacture of the lights? Do all of the lights dim, or just some of them. Are they split across the phases and are there any other accessories supplied by these phases? e.g. any socket outlets off the same phase as the lights that dim? So if the voltage is staying the same what is happening to the current during this dimming phenomena? How long ago were they installed, weeks, months?

Doc H.

 

[Steady Eddy]

Hi I have had a similar problem recently in a Cafe. The customer complained that when he turned his kitchen hood extract fan on the lights dimmed.The problem had started a couple years ago but had been workong fine before that.Having made all the obvious checks I could find nothing wrong with the wiring switches etc and there were no volt drop issues. The light fittings were 2 x 26w CFL downlighters. I noticed that a couple of fittings did not dim and when I investigated I found they were a different make to the other light units and the control gear was of a different make. I then considered that there must be some electrical interference being generated by the fan. I bought a RFI Filter (radio frequency interference filter) which I installed at the supply to one of the light fittings and it stopped it from dimming.

Installing the RFI filter at the motor terminals did not stop the lights dimming.

I recommended to the customer that he gets the fan motor replaced / repaired. The alternative is to fit RFI filters to each fitting or replace the fittings .

Hope this helps.