This article is for general information. Always refer to local electrical codes for acceptable installations.
This article addresses 0-10 volt dc controlled light fixtures. While the main focus will be on LED lighting, the information could be applied to 0-10 volt lighting installations with fluorescent as well. The use of the 0-10 volt control signal has been used with fluorescent fixtures and has been applied to the more recent LED lighting.
There are two lighting standards that use 0-10 volt control signals. One that has the controller source current (power coming out of the controller), and one that sinks current (the control drawing current from the ballast/led driver). This second method is typically used in most lighting applications. This document will refer to the device controlling the 0-10 volt signal as the “control” or “controller” and the device under control as the “ballast” or “driver”.
Phason’s 0-10 vdc outputs are designed to source current for driving VFDs and other control equipment, and also designed to sink current for lighting applications.
The control range for many ballasts is from 1 – 10 volts. One volt gives the minimum light output and 10 volts the maximum light output. Some ballasts will extinguish the light from the lamp when the voltage is at or below 0.5 volts. Many will remain at the minimum brightness even with the control voltage at 0 volts. In this case, to extinguish the light the AC needs to be disconnected. For this situation a “follower” relay function is available in our lighting controls.
It is very important to note that the light output is maximum at 10 volts, and minimum at 1 volt. (typically) There is no defined output for the range between these two extremes. A control voltage of 4 volts with one model of light may produce a certain light output and another model could produce a totally different output with the same 4 volts. They could have very different output characteristics. Ensure that the fixtures you use are the same, or compatible, models.
The ballast sources current out of the positive connection of the 0-10 volt control connection. You need to know the maximum current the ballast will source when the control is at the 0 volt level. (minimum brightness) This is typically 1 mA or less. The controller can control multiple fixtures up to the maximum rated limit. For the VDC-4 the maximum current is 100 mA per output. If the fixture had a max current of 2 mA, then the maximum number of fixtures that can be connected to the VDC-4 output would be 50.
Typically the color used for the 0-10 volt control wires is Gray for –ve and Violet for +ve. It is very important to connect the + and – wires to the indicated + and – terminals on the control. A reversed polarity may damage the control. It is recommended to use twisted pair wires for the 0-10 volt control signal to reduce electrical noise pickup.
LED lights tend to be low wattage devices. What is often missed is that they can have a high inrush current. This is a concern when it comes to the AC line relay or switch. The inrush current is often 50-100 times the steady state current. Careful consideration must be given to the inrush capability of the switch (relay) that will supply the AC to the LED fixtures.