Alarm relay connections, Connections – Precision Digital PD138 User Manual
Page 18
PD138 Minimux
®
II Temp & Process Scanner
Instruction Manual
18
ALARM RELAY CONNECTIONS
One SPDT relay is provided with each unit. This alarm relay is common
to all channels and is activated when the PD138 detects an alarm. The
relay resets when the alarm is acknowledged.
Connections
Refer to the diagram below to wire up the alarm relay.
When connecting two or more Minimux
®
II together it may be necessary
to wire the relays in parallel to drive a single alarm device.
For fail-safe operation, the relay is energized in the non-alarm state. In
the case of a power failure, the relay will go to the alarm state, (NC
contact is connected to C). See page 23 for details