ProtEX-MAX PD8-6001 Explosion-Proof Feet & Inches Meter Instruction Manual
34
Setting Fail-Safe Operation
In fail-safe mode of operation, the relay coil is energized when the process variable is within safe limits and the relay
coil is de-energized when the alarm condition exists. The fail-safe operation is set independently for each relay.
Select
on
to enable or select
off
to disable fail-safe operation.
Programming Time Delay
The
On
and
Off
time delays may be programmed for each relay between 0 and 999.9 seconds. The relays will
transfer only after the condition has been maintained for the corresponding time delay.
The
On
time delay is associated with the set point.
The
Off
time delay is associated with the reset point.
Relay Action for Loss of 4-20 mA Input (Loop Break)
The loop break feature is associated with the 4-20 mA input. Each relay may be programmed to go to one of the
following conditions when the meter detects the loss of the input signal (i.e. < 0.005 mA):
1. Turn
On
(Go to alarm condition)
2. Turn
Off
(Go to non-alarm condition)
3. Ignore (Processed as a low signal condition)
Note: This is not a true loop break condition; if the signal drops below 0.005 mA, it is interpreted as a “loop break”
condition.
Relay and Alarm Operation Diagrams
The following graphs illustrate the operation of the relays, status LEDs, and ACK button.
High Alarm Operation (Set > Reset)
For Manual reset mode, ACK can be pressed anytime
to turn "off" relay. To detect a new alarm condition, the
signal must go below the set point, and then go above
it.
Low Alarm Operation (Set < Reset)
For Manual reset mode, ACK can be pressed anytime
to turn "off" relay. For relay to turn back “on”, signal
must go above set point and then go below it.
