WAC155 also provides the sensors with a throughput and control of heating power, which can be connected if sensor heating is required. The heating power circuit is galvanically isolated from the operating power circuit.
The heating power connection requires an extra pair of wires. Since the required heating current for the WA15 series is typically 0.5 ... 1 A, it is most conveniently supplied from a local power source. WAC155 automatically connects heating power in temperatures below +4 °C (39.2 F).
There are two ways to connect the heating power, depending on the heating power supply available. The default way is to use a 40 V power supply and connect the heating elements of the sensors in series.
|When connecting DC heating power, make sure you have the correct polarity of the X2 connector pins 1 and 2 (HT1+ and HT2-). AC heating power wires can be connected either way round.|
You can use the 40 V power supply only when both sensors are connected. The sensor heating elements have a 40 Ω resistance each. The typical heating current is 0.5 A in a series-connected system with a 40 V power supply.
If you use a 20 V power supply, you must connect the sensor heating elements in parallel. The following figure shows the parallel connection. In this case, the typical current demand is 0.5 A + 0.5 A = 1 A.
When you only install one sensor, anemometer WAA151 or wind vane WAV151, you must use a 20 V power supply and replace the missing sensor heating element with a jumper wire. In this case, only 0.5 A is typically consumed.