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Electronic Theatre Controls Inc

Non-Dim vs Switched Mode - Regulated vs Unregulated

Quick Summary:

If you've got devices with electronics inside being powered from a dimmer in an ETC Sensor rack, set the firing mode to switched. On a Unison rack, or in some software versions of SmartPack, SmartBar, or SmartModule, set the mode to non-dim

What those options mean:

  • Non-dim dimmers output regulated AC voltage when the DMX512 level is higher than the threshold level.
  • Switched dimmers output unregulated AC voltage when the DMX512 level is higher than the threshold level.

See also : LED Fixtures and Moving Lights Powered by ETC Dimmers

Setting an ETC Sensor dimmer to full is not the same as turning on a non-dimmed circuit. Dimming systems that have regulation limit the maximum RMS voltage to the level at which regulation was set. With regulation, you can feed a rack more than 120V, and each dimmer will throttle back the voltage to 120v (or whatever is programmed to protect 115V or 120V lamps from overvoltage). Another benefit of regulation is that it can keep outputs from changing when input feeds change due to power grid loading or unloading -  the lights will always appear at the same "brightness" from day to day. 

The downside of regulation is if a dimmer is set to full and it is regulating, you will not get a full sine wave, which can harm many moving lights and other AC devices (foggers, computers, etc).

There are a couple of ways to deal with this. The best method is to use a module with a relay in it, in place of a dimmer module. (In Sensor or Unison racks, that would be a module whose name begins with R followed by some numbers, or in Sensor+ and Sensor3, a TR20AF or TR20SAF module). Otherwise, you may be able to set the firing mode of the dimmer to Switched or Non-dim (for Sensor use Switched) which will give you very close to a sinewave and will work for almost any load type.

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