WEST P4100 - Exceed Condition; Limit Output Function; Limit Annunciator Outputs; -DIN, 1; 8 -DIN & 1; 16 - DIN Controllers & Indicators - Product Manual

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- DIN Controllers & Indicators - Product Manual
59305, Issue 5 – March 2005 P6700, P8700 & P4700 Model Group Page 65
Exceed Condition
An Exceed Condition occurs when the Process Variable exceeds the Limit Setpoint value
(i.e. PV is greater than the Limit Setpoint when set for high limit action, PV is less than the
Limit Setpoint for low limit action). The LED is on during this condition, and is
extinguished once it has passed.
Limit Output Function
The Limit Output relay(s) de-energise whenever an Exceed condition occurs, causing the
process to shut down. The LED is on when the relay is de-energised.
The relay remains latched off even if the Exceed condition is no longer present. A reset
instruction must be given after the exceed condition has passed to re-energise the relay,
allowing the process to continue. The LED then turns off.
Limit Annunciator Outputs
An Annunciator output will activate when an Exceed condition occurs, and will remain active
until a reset instruction is received, or the Exceed condition has passed. Unlike the Limit
Output, an Annunciator can be reset even if the Exceed condition is present. When an
Annunciator is active, the LED will flash and the Alarm Status screen is available.
Resetting Limit Outputs & Annunciators
A reset instruction can be given by any of the following methods. The front panel Reset key,
the Digital Input (if fitted) or via Serial Communications command if an RS485
Communications module is fitted.
Using The Reset Key To Reset Limit Outputs & Annunciators
Press the key reset an active Annunciator or latched Limit Relay.
Note:
Annunciators will deactivate immediately, Limit Outputs will only re-energise if the Exceed
condition has passed.
CAUTION:
Ensure that the cause of the Exceed condition has been rectified before resetting
the Limit Output.
Resetting Limit Hold and Exceed Time
The highest PV value reached (for High Limit action) or lowest PV value reached (for Low
Limit action) and the accumulated time of Limit SP exceed conditions can be viewed.
To reset the stored Limit Hold and Exceed Time values
Display the value to be reset, the press the key for 5 seconds. The upper display
briefly shows 8888 when the value is reset.