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mickymicky

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Hi, I'm new to the forum.
I have a domestic installation with; 14No 35watt lv lamps= 490 watts.
controlled by 5No 105va 'Mode' leading edge transformers = 525Va
I am trying to dim the circuit with a Richmond (now Zano) Grid 700 rotary dimmer module that uses leading edge technology, max lv load recommended 600 watts. The system works ok until the last 2 degrees of turn of the rotary switch, the connected load then begins to pulse (flash). At the same installation I have another Richmond grid 700 dimmer controlling 8No 35watt lv lamps on 8No collingwood 60Va leading edge transformers. This circuit operates without a problem. I have swopped the switches to check if I have one faulty switch but both work on the 8 light circuit. I previously had collingwood transformers in problem circuit with same problem. Both switch and transformer manufacturers are confident that their product is up to the job. What am I doing wrong ?
 
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MarkieSparkie

  • Thread Starter Thread Starter
  • #3
I believe on your problem LV lighting circuit the dimmer is seeing the transformers, lamps and associated wiring as a capacitive reactive load, and at low dimming levels this causes the dimmer to become unstable, leading edge dimmers are susceptible to this type of problem load. The usual way of curing this instability is to either swamp the circuit with high power load resistor, or to change the dimmer to a trailing edge type. You will need to consult the dimmer and transformer manufactures for advice. If memory serves Richmond offer a free transformer compatibility check with their dimmer products, however this may be a paper exercise rather than a laboratory test with your particular lighting load and conditions.
 
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