Chapter 3 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 59
Alarm Relays
DMT340 can be equipped with one or two configurable relay modules.
Each module contains two configurable relays. See the contact ratings in
section Technical Specifications of Optional Modules on page 172.
Installation and Wiring
1.
Disconnect the power. In case the relay-module is installed in the
factory, continue with the step 5.
2.
To attach the module, open the transmitter cover and fasten the
relay module to the bottom of the housing with four screws. See the
position in Figure 2 on page 20.
3.
When the mains power is in use attach the grounding wire to the
grounding terminal.
4.
Connect the flat cable between the relay module and the
motherboard's pins
MODULE 2
or
MODULE 1.
5.
Take out the protective plug from the cable gland and thread the
relay wires.
6.
Connect the wires to the screw terminals: NO, C, and NC.
CAUTION
For installations in the USA: If your transmitter has both the relay
module and a LAN or WLAN module, the maximum voltage you are
allowed to connect to the relay module is 50 V.
Selecting the Activation State of the Relay
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, selecting quantity for the relay output and
setting the relay setpoints), see section Operation of Relays on page 129.
