Red Lion PCU - Manual (Page 37)

Second Analog Input Alarm
On models equipped with the Second Analog Input, the alarm(s) may be
configured to monitor the second input reading in addition to the main input.
Refer to the corresponding alarm operation figures for operation modes.
Note that deviation and band alarm modes are only valid for Internal
Cascade operation.
Absolute High Acting -2 (A2HI)
Absolute Low Acting -2 (A2LO)
Deviation High Acting -2 (d2HI) ь
э
ю
Relative to SP-2, Second
Input (Internal Cascade) Deviation Low Acting -2 (d2LO)
Band Inside Acting -2 (b2IN)
Band Outside Acting -2 (b2Ot)
Valve Fail Alarm (VFAL)
On models equipped with Valve Positioner (Position mode control only),
Alarm #1 may be configured as a valve fail alarm (Act1 = valv). This alarm
mode is useful to provide early detection of valve failure before significant
process errors occur. In this mode, the usual alarm function is disabled.
The alarm triggers under the two following conditions:
1. The valve slidewire feedback position does not match the controller output
power (within the valve position deadband) after the valve fail time has
expired. The alarm indicates that the valve cannot be properly positioned
due to a malfunction of the valve or valve positioner.
2. The slidewire feedback signal is broken or out of range. In this case, the
valve position controller cannot position the valve.
Message display alarms “valv” and “slid” appear when conditions 1 and 2
occur, respectively, whether or not the alarm is configured as a valve fail
alarm. This alarm mode also applies to linear DC output used for valve
positioning. In this case, a slidewire signal must be supplied to the controller
for valve fail detection. To silence a triggered Valve Fail alarm, see
Valve
Fail Time Alarm (VFAL) parameter, page 38.
The alarm action figures describe the status of the alarm output and the
front panel indicator for various over/under process conditions. (See
Output
Module “OUTPUT ON” State Table, page 6, for definitions, under installing
output modules section.) The alarm output wave form is shown with the
output in the automatic reset mode.
Note: Select the alarm action with care. In some configurations, the front panel
indicator (LED) might be “OFF” while the output is “ON”.
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