
Chapter 3 ________________________________________________________________ Installation
VAISALA________________________________________________________________________ 47
Selecting Relay Activation State
The middlemost C terminal and either one of the terminals NO/NC
shall be connected. The polarity can be freely selected.
NO
Normally open
C
Common relay
NC
Normally closed
Relay NOT activated: C and NC outputs are closed, NO is open
Relay IS activated: C and NO outputs are closed, NC is open.
Connect the power and close the cover. For instructions on how to
operate the relay (for example, select quantity for the relay output and
set the relay setpoints) see section Relay Operation on page 91.
0605-032
Figure 30 Relay Module
Numbers refer to Figure 30 above:
1 = Indication led for the relay 1 or 3
2 = Relay test buttons
3 = Flat cable pins
4 = Indication led for relay 2 or 4
WARNING
The relay module may contain dangerous voltages even if the
transmitter power has been disconnected. Before working on the
relay module you must switch off both the transmitter and the
voltage connected to the relay terminals.
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