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Electronic Theatre Controls Inc

Voltage Regulation in Sensor and Unison DRd Racks

How does voltage regulation work?

Dimming modules work  by changing the point at which the loads turn on by changing the pulse width.  If line voltage increases, the height of sine wave increases.  However, if the pulse width stays in the same place, the area under the sine wave will still increase.  If we adjust the length of the pulse width though, we can keep the  area under the sine wave the same thus keeping the output of the dimmer the same. When metering this output, we are actually trying to meter the area under the sine wave as opposed to just peek to peek.  In order to calculate this, we need a meter that will measure the Root of the Mean Square of the wave, or RMS. Most RMS meters will  specifically say “True RMS” on the label if they are able to read this calculation.

There are a few adjustments you can make available in Sensor Racks And Unison Paradigm DRd racks. These adjustments can be made but do need to follow a few rules:
-You can only use voltage regulation to trim the top end of the dimmer.

-You will need at least 5v (may be more if you have long runs)  between in coming voltage and what set as Max output voltage.

-You can set the maximum voltage of the rack type, that is 140V for US racks and 280V for CE or HSR racks, but if you do not have that  level voltage coming in to the rack, you will never get it out of the rack, We dim down the lights, we do not make more voltage than what is coming in, sorry.

 -Do not mix load types on a dimmer if you are making these adjustments.  While it may improve one load types performance, it could degrade a different load type on the same circuit.

This process of regulation works great for incandescent loads.  It does not work well for most LED drivers.  LED drivers use the pulse width to determine output level.  If we are modifying the pulse width to change the area under the sine wave, the LED driver will interpret this information as a range of level. This would then cause normally "steady states" in the output to cause the LED to waver. In these cases- voltage regulation should be turned off for the dimmer.  



The information in this post is provided to assist in troubleshooting. Perform work at your own risk. ENSURE ANY POWER FROM DEVICES HAS BEEN DISCONNECTED BEFORE SERVICING ANY EQUIPMENT. If you do not feel comfortable performing the work, please contact us or your local service center. Be aware that ETC and its Affiliates are not responsible for any damage or injury caused by service of our products by anyone other than us or our authorized service providers, and such damage is excluded from the product’s warranty.

Please follow all NFPA70 Guidelines.


Set the loads for all the the circuits.
You will need to to pick a point that you want all your dimmers to be trimmed to. 
This will want to be just below the lowest level that all your dimmers can reach. 
The dimmer can only turn down the lights and can not actually create power- that is being provide by the electrical grid.
Since wire length is one of the largest determining factors, it is best to start on the circuits with the longest wire runs, and work your way back from there.

You will need a way to connect a TrueRMS meter to the circuit in roughly the same place 
An adapter connects the meter between the connector type being used (stage-pin, Edson, Twist-lock, etc) to convection to the distro and the tail of fixture, is a good constant place to do this. 
Place the meter in line and take the circuit to full. 
Lets say your device going in to the racks is 121VAC.  At your longest circuit the voltage is 111.5VAC  then 110v would be a good place to trim to.  
So now what you do is adjust the output of the dimmer to read 110v at the fixture. The you do this same procedure for all the circuits you would like to be at the same level of voltage.

CEM + CEM 3  and Unison DRd racks  

To trim voltage output on a Sensor CEM system Unison Paradigm DRd racks, the adjustments are all in Dimmer settings.
Per Circuit: Turn regulation on and change max Scale Voltage to adjust output. This # is in volts but will not exactly match the # on the meter because of voltage drop on the line.   

CEM Classic

3.x software there are less options for setting
Regulation was always on unless you chose Switched or  as an output, Non-dimmed (is a On/Off output puts but still regulated) Setting Max dimmer output was called “Scale Voltage”
2.x software there are even less setting available. Setting Max dimmer output was called “boost Voltage”

See control processor manuals for more specific directions.

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