172-65608MA-03 (RGDS) 5 Oct 2021
17
Item
Cause
Diagnostic
Remedy
Does not reach
desired steam
pressure
There is a
problem with the
input current of
the pressure
control valve
Check that a signal of 4
– 20 mA is
being received from the pressure
sensor at the connection terminals
Adjust the controller or
replace with a new
controller
Supply steam
pressure is too
low
Check whether there is a correct
steam pressure
Supply steam at the
correct pressure
Temperature
does not go
down
Operation at a
temperature
outside the
operating
specifications
Check the specifications
Operate within the
range of the operating
specifications
There is
insufficient
desuperheating
water
The Y-strainer installed on the
desuperheating water line is
blocked
Clean the Y-strainer
The lifting height of the pump has
decreased
If the pump lifting
height has decreased,
replace with a new
pump
Check the aperture of the
temperature control valve
(Check whether the value on the
controller and the valve aperture
match)
Correct the air
pressure supplied to
the positioner
Repair any air
leakages between the
temperature control
valve actuator and
positioner
The PID set
values are
incorrect
Check the PID set values
Correct the PID set
values
The temperature
sensor is
malfunctioning
Check the temperature value
reading from the sensor and
compare with the temperature
gauge, if the electrical wiring and
signal are normal, then the
temperature sensor is
malfunctioning
Replace with a new
temperature sensor
Temperature is
below the set
value
The temperature
sensor is
malfunctioning
Check the temperature value
reading from the sensor and
compare with the temperature
gauge, if the electrical wiring and
signal are normal, then the
temperature sensor is
malfunctioning
Replace with a new
temperature sensor
The condensate
separator is
blocked
Condensate is not being
discharged, the surface
temperature of the separator is cold
Perform maintenance
on the separator or
replace with a new
separator
The temperature
sensor is
installed wrong
The probe section of the
temperature sensor is not in the
center of the piping
(The sensor is measuring the
temperature of the condensate on
the bottom of the piping)
Correct the installed
length of the
temperature sensor
Continued on the next page
