Dynasonics DDFXD Doppler Ultrasonic Flow Meter - Manual (Page 34)

34 06-DPP-UM-00147 02/12
OUT (-)
IN (+)
I/O: 4-20 mA
P.N. D020-1045-100
ISO-MOD
JP2
JP1
INT PWR EXT PWR
RTU/PLC
MONITOR
Remove
Jumpers
4-20 mA IN (+)
4-20 mA OUT (-)
FIGURE 3.10C - EXTERNALLY POWERED 4-20 mA
CONTROL RELAY OUTPUT MODULE
Two independent SPDT (single-pole, double-throw, Form C) relays are contained in this module. The
relay operations are user configured via the front panel to act in either a flow rate alarm, error alarm or
totalizing pulse. The relays are rated for 200 VAC maximum and have a current rating of 0.5 A resistive
load (175 VDC @ 0.25 A resistive). It is highly recommended that a secondary relay be utilized whenever
the Control Relay ISO-MOD is used to control inductive loads such as solenoids and motors.
Typical relay connections are illustrated in Figure 3.11A. The reed relays located within the relay module
can interface directly with small pilot lights, PLCs, electronic counters and SCADA systems.
Figure 3.11B describes the connection of an external power relay to the Relay ISO-MOD. It is recom-
mended that external power relays are utilized whenever the load to be switched exceeds the switch
rating of the reed relays, or if the load is inductive in nature.
b NO
b CM
b NC
a NO
a CM
a NC
I/O: RE L AY
P.N. D020-1045-102
ISO
-MOD
INTERNAL
CURCUIT
FLOW OK
LOW FLOW
EXTERNAL
TOTALIZER/SAMPLER
P
FIGURE 3.11A - TYPICAL RELAY CONNECTIONS