
63
14.3 PV
Problem
Presumed cause and solution
PV is high.
• Thermocouple, RTD or DC voltage (0 to 1V DC) is burnt
out.
Change each sensor.
How to check whether the sensor is burnt out
[Thermocouple]
If the input terminal of the instrument is shorted and if
a value around room temperature is indicated, the
instrument is likely to be operating normally, however, the
sensor may be burnt out.
[RTD]
If approximate 100 of resistance is connected to the
input terminals between A-B of the instrument and
between B-B is shorted, and if approximate 0 (32 ) is
indicated, the instrument is likely to be operating normally,
however, the sensor may be burnt out.
[DC voltage (0 to 1V DC)]
If the input terminal of the instrument is shorted and if a
scaling low limit value is indicated, the instrument is likely
to be operating normally, however, the signal wire may be
disconnected.
• Check whether the input signal wires of thermocouple, RTD or
DC voltage (0 to 1V DC) are securely connected to the
instrument input terminals.
Ensure that the sensor terminals are connected to the
instrument input terminals securely.
PV is low.
• Check whether the input signal source for DC voltage (1 to
5V DC) or DC current (4 to 20mA DC) is disconnected.
How to check whether the input signal wire is
disconnected
[DC voltage (1 to 5V DC)]
If the input to the input terminals of the instrument is 1V
DC and if a scaling low limit value is indicated, the
instrument is likely to be operating normally, however, the
signal wire may be disconnected.
[DC current (4 to 20mA DC)]
If the input to the input terminals of the instrument is 4mA
DC and if a scaling low limit value is indicated, the
instrument is likely to be operating normally, however, the
signal wire may be disconnected.
• Check whether the input signal wire for DC voltage (1 to 5V
DC) or DC current (4 to 20mA DC) is securely connected
to the instrument input terminals.
• Check whether the polarity of thermocouple or
compensating lead wire is correct.
Check whether codes (A, B, B) of the RTD agree with the
instrument terminals.
Ensure that they are wired properly.
The indication of
PV display is
abnormal or unstable.
• The sensor input or temperature unit ( or ) setting
is improper.
Set the sensor input and the temperature unit properly.
• Sensor correcting value is unsuitable.
Set it to a suitable value.