Selecting the activation state of the relay – Vaisala PTB330 User Manual
Page 43
Chapter 3 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 41
Selecting the Activation State of
the Relay
The middlemost C terminal and either one of the terminals NO/NC
must be connected. The polarity can be freely selected.
NO
Normally
open
C
Common relay contact
NC
Normally
closed
Relay NOT activated:
C and NC outputs are closed, NO is open
Relay IS activated:
C and NO outputs are closed, C and NC are open.
NOTE
For instructions on how to operate the relay (for example, select
quantity for the relay output and set the relay setpoints) see section
Operating Relays on page 93.
Figure 24
Relay Module
Numbers refer to Figure 24 above:
1
=
Indication led for the relay 1
2
=
Relay test buttons
3
=
Flat cable pins
4
=
Indication led for relay 2