Vaisala GMT220 - Manual (Page 16)

USER'S GUIDE____________________________________________________________________
16 __________________________________________________________________ M010022EN-F
The following numbers refer to Figure 6 on page 15:
1 = Current output jumper (4 mA)
2 = Relay jumpers L1 and L2
3 = A, B, C and D: Not intended for customer use
4 = Relay 2 terminals
5 = Relay 1 terminals
6 = Serial port
7 = Power supply terminals
8 = Output terminals
Power Supply Requirements
The GMT220 series transmitters are designed to operate with a nominal
24 VAC/DC supply. The power supply should maintain the voltage for
all load conditions and all mains voltages. The power input includes a
halfwave rectifier. To avoid current peaks, it is recommended to use a
DC supply.
Connection to a 24 VAC Supply
The GMT220 series transmitters can be connected to a 24 VAC supply
without an external rectifier. However, when more than one transmitter is
connected to one 24 VAC transformer, a common loop is formed and risk
of a short-circuit increases. To avoid this, always use separate floating
supply for each transmitter, see Figure 7 A on page 17.
CAUTION If several transmitters have to share one transformer, the phase (
) must
always be connected to (+) connector (24 V) in each transmitter, see
Figure 7 B on page 17.