Caution – Wavetronix Click 500 (programmable controller) (CLK-500) - Developer Guide User Manual
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CHAPTER 1 • USING THE CLICK 500 21
Figure 1.9 – Transformers
Caution
Do not connect 110 VAC or higher directly to a digital input when it is configured to
monitor low-level AC. Always use an AC current transformer to reduce the magnitude
of the AC voltage.
The intended application for the AC input transformers is to measure which of the signal
indications (red, yellow, green) on a standard incandescent or LED signal light is illumi-
nated. These inputs can be used with any type of standard traffic cabinet to determine which
indications are on or off. When enough current is being supplied by the traffic cabinet load
switches to activate a 1 W load, the digital input will signal that AC is on (otherwise, the
input will signal that the AC is off). This high-level of sensitivity allows the input to work
with low-power LED signal lights that draw only 5 W.
Note
See Chapter 9 for information on how to connect one input to the red indication wire
and another to the yellow indication wire to determine if the light is red, yellow or
green.
When used to monitor low-level AC, the digital inputs can also be used in any other indus-
trial application where it is necessary to determine if an AC load is powered on or off. For
example, an alarm could be generated if a device, which is supposed to run continuously,
turns off.