Dynasonics DDFXD Doppler Ultrasonic Flow Meter - Manual (Page 45)

06-DPP-UM-00147 02/12 45
ISO-MOD DUAL RELAY CONFIGURATION
DUAL RELAY
RELAY 1 AND RELAY 2
NONE
TOTAL
FLOW
OFF <
ON >
ERRORS
Two independent SPDT (single-pole, double-throw, Form C) relays are contained in this module. The re-
lay operations are user configured via the keypad to act in either a total pulse output, flow rate alarm or
error alarm mode. The relays are rated for 200 VAC maximum and a have 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.
TOTALIZER RELAY
TOTAL mode configures the relay to output a 50 mSec pulse (contact changeover) each time the display
totalizer increments.
FLOW RATE RELAY
Flow Rate Relay configuration permits relay changeover at two separate flow rates allowing operation
with an adjustable switch deadband. Figure 4.3 illustrates how the setting of the two set points influ-
ences Rate Alarm operation.
A single-point flow rate alarm would place the ON> setting slightly higher than the OFF< setting – allow-
ing a switch deadband to be established. If a deadband is not established, switch chatter (rapid switch-
ing) may result if the flow rate is very close to the switch point.
Minimum
Flow
Maximum
Flow
Output ON S
et OFF
S
et ON
Deadband
Output OFF
FIGURE 4.3 - SINGLE POINT ALARM OPERATION