Power Supply Requirements - Vaisala GMW20 Handbuch

User's Guide _____________________________________________________ GMW20
Power Supply
Requirements
The GMW20 uses a nominal 24 VAC/VDC power supply
maintaining a voltage of 18...30 VDC or 20...26 VAC for all load
conditions and all mains voltages. Although the power input
includes a halfwave rectifier, it is recommended to use a DC
supply to avoid current peaks (Current consumption: peak 170
mA, average 85 mA).
Connections to a 24 VAC Power Supply
When more than one transmitter is connected to one 24 VAC
transformer, a common loop is formed and the risk of a short-
circuit increases. To avoid this, separate floating supply for
each transmitter is recommended (see Figure 3).
In case where several transmitters have to share one

transformer, the phase ( ) must always be connected to 24V
connector in each transmitter to maintain the "polarity" and to
avoid short-circuit via shared common line at the controller as
shown in Figure 4.
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