User Manual

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 congured via the keypad to act in either a total pulse output, ow 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 congures the relay to output a 50 mSec pulse (contact changeover) each time the display
totalizer increments.
FLOW RATE RELAY
Flow Rate Relay conguration permits relay changeover at two separate ow rates allowing operation
with an adjustable switch deadband. Figure 4.3 illustrates how the setting of the two set points inu-
ences Rate Alarm operation.
A single-point ow 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 ow rate is very close to the switch point.
Minimum
Flow
Maximum
Flow
Output ON
Set OFF
Set ON
Deadband
Output OFF
FIGURE 4.3  SINGLE POINT ALARM OPERATION