Input and Output Signals
Publication
PUB091-004-00_0918
33 of 64
thermostat. The bit will remain set at logic 1 until the motor cools down
and the thermostat resets itself.
Monitor Relay
This signal is true (1) when actuator remote control is not available.
The actuator Monitor Relay status is a composite signal for several
alarms. This signal will be set true if the actuator selector is in Local or
Local Stop (not in Remote) or if the thermostat trips. The mains supply
is also monitored and if one of the three phases is lost, this bit is set. If
the actuator is operated from a single phase supply and this is lost,
then communications with the actuator will also be lost. Where a 3
phase supply is used, if the phase associated with the control circuits
is lost then communications with the actuator will be lost.
Valve Obstructed
This bit will be true (1) if the actuator stops in mid travel when
not expected to do so after receiving a command to move. If the
actuator torque exceeds the trip value set during commissioning, then
the motor will stop and motion will cease. The reason for the actuator
stopping will be the high torque due to an obstruction and not to a
‘Stop’ signal or reaching the desired setpoint position.
The bit will remain true (1) until the actuator position changes by 2%
or more.
Valve Jammed
This bit will be true (1) if the actuator is stationary at the end of travel
and fails to move away from the seat of the valve when a network
command requests it to do so. The actuator will trip on excessive
torque due to the valve being jammed in the seat. The MFU fails to
see movement and reports this status after the time set in the
associated parameter during the MFU set up.
The bit will remain true (1) until the actuator position changes by 2%
or more.
Valve Moving by Hand
The manual movement of the valve is reported as true (1)
if the actuator is moved by the handwheel away from the last position.
The percentage of travel required to trip the indication is set in the
associated parameter (Register 17) during MFU set up.
The bit will remain true (1) until the handwheel is again stationary.
Note:
Attempting to restart the actuator to move towards the obstruction (even if the
obstruction no longer exists) is not possible, as the actuator will not restart. The actuator
must be electrically reversed away from the obstruction before attempting to continue in
the original direction.
Note:
Attempting to restart the actuator to move out of the seated position is not possible. The
actuator must be reversed before it will run in the same direction again. The jammed
seat must first be released manually before electrical control is attempted. The problem
may be overcome by adjusting the actuator torque setting, which is designed to provide
extra power on leaving the seated position.
