172-65627M-09 (SQ10) 18 Oct 2021
36
Problem
Cause
Diagnosis
Remedy
Water
temperature
is unstable
Large
fluctuations in
amount of water
used.
Check the operating
conditions.
Reduce sudden changes
in the amount of water
used. (Refer to the
"Temperature Stability"
area of this section.)
Inlet steam
pressure of the
control valve is
unstable.
Check the steam
pressure.
Make sure a steam
supply pressure of 0.4
MPaG is obtainable up
until the unit.
Air supply pressure
to the control valve
is unstable.
Check the air supply
pressure to the control
valve.
Supply required
pressure.
Build-up or wear
in the control
valve or valve
seats.
Check the closing sound
of the control valve at a
temperature below the
set temperature.
Maintenance is
necessary when a high-
pitched steam flow sound
can be heard.
The PID is not
appropriate.
Check the PID.
Change the PID to a
proper value.
Abnormal
system
alarm 1 is
triggered
One or more of
the following 4
malfunctions are
occurring:
1. Malfunction of
the internal
sequencer parts
2. The
temperature
sensor is broken
3. Wiring between
the sensor and
sequencer is
disconnected
4. Wiring for
measured
temp. value
output is
disconnected
or a problem
has occurred at
the output
location.
(When using
measured temp.
value output)
Follow the steps below to
resolve problems.
(1) When using
measured temp.
value output,
disconnect the wiring
and connect it to a
250
Ω resistor.
(2) Confirm continuity
between the
temperature sensor
and the sequencer.
(3) Replace the
temperature sensor
with a working
sensor, then
reconfirm the
continuity between
the temperature
sensor and the
sequencer.
If the alarm is resolved
when implementing
diagnosis (1), cause 4. is
likely to be the problem.
Correct the output
location and wiring.
If continuity between the
temperature sensor and
the sequencer cannot be
confirmed for diagnosis
(2), cause 3. is likely to
be the problem. Replace
the wiring.
If the alarm is resolved
when implementing
diagnosis (3), cause 2. is
likely to be the problem.
Replace with a new
temperature sensor.
If the alarm is not
resolved after
implementing diagnoses
(1) to (3), cause 1. is
likely to be the problem.
Replace the sequencer.
Abnormal
system
alarm 2 is
triggered
Malfunction of
the internal
sequencer parts.
Replace the sequencer.
Malfunction of
the control valve
or the solenoid
valve of the
steam supply
unit.
Confirm the valve
opening and the
temperature of the piping
before and after the
control valve or the
solenoid valve of the
steam supply unit.
Replace the valve with a
large temperature
difference in the piping
before/after the valve.
NOTE: Refer to individual instruction manuals for problems with other components.
