RFL SMX3 / 21
Page 19 of 22
Issue 1.4
User Manual
08 June 2009
12. Power Input
Power input is 48 Vdc nominal. (24V – 72V range).
SMX3/21 can be connected to positive earth, negative earth or floating supplies.
The power connections P1 and P2 are not polarity sensitive, but when using a
grounded supply, the 0V leg must be connected to P2. (See table)
A 500mA fuse (5 x 20mm) is in the rail connected to the P1 terminal.
A separate earth connection is required to the M4 Earth stud provided.
Power Input Connections
Type of supply
Terminal P1
Terminal P2
Earth stud
Positive Earth
– 48Vdc
0V
Main Earth
Negative Earth
+48Vdc
0V
Main Earth
Floating Either Either
Main
Earth
13. Alarms
Two alarm relays are incorporated, energised when healthy. Each relay provides a
single changeover contact presented on a plug-in terminal strip, see equipment
layout. For a contact that closes on alarm, use common and NC connections.
•
Power alarm:
Energised when healthy
Alarm state is when applied voltage falls below nominal minimum voltage.
•
Aggregate communications alarm:
Alarm state is when any of the following conditions are present on either the
X.21 or Concatenation ports (only when enabled):
Aggregate port configuration error
No
clock
present
Aggregate frame not synchronised
Yellow alarm (remote alarm)
Alarm Connections
Function Terminal Contact
Notes
A
NC
Closed in alarm state
B Common
Aggregate
Comms Alarm
C
NO
Closed when healthy
D
NC
Closed in alarm state
E Common
Power Alarm
F
NO
Closed when healthy
