Emerson Rosemount5081, Инструкция по эксплуатации, Страница: 71 / 152

CALIbrAtE
CALIbrAte is a diagnostic intended for future use. If the CALIbrAte message is showing,
disable CALIbrAte .
tEMP HI and tEMP LO
tEMP HI and tEMP LO mean the transmitter has detected a problem with the temperature
measuring circuit. The problem may lie in the sensor, the cable, or the transmitter. The
determination of temperature is an integral part of the pH measurement. Therefore,
failure of the temperature measuring circuit is a system disabling condition. However, in
an emergency, automatic temperature compensation can be disabled and the transmitter
placed in manual temperature compensation. For manual temperature compensation,
choose a temperature equal to the average temperature of the process. The resulting pH
reading will be in error. The more variable the temperature and the further the pH from 7,
the greater the error.
Troubleshooting flowchart - tEMP HI and tEMP LO
1. Check wiring, jumper settings, and software settings.
a. Check the wiring between the sensor and the transmitter. Pay particular
attention to TB=3 (RTD RTN), TB-4 (RTD SN), and TB-5 (RTD RTN ).
NOTICE
TB-3 means terminal 3 on the terminal board.
b. Be sure the software settings match the type of RTD in the sensor.
• If the diagnostic message disappears, the sensor is in good condition.
• If the message persists, go to Step 2.
2. Check the sensor. Disconnect the RTD leads and measure the resistances shown in
Figure 8-3 . The measured resistance should agree with the value in Table 8-1 to
within about 1%. If the measured resistance is appreciably different (between 1 and
5%) from the value shown, the discrepancy can be calibrated out.
Diagnostics and troubleshooting
Instruction Manual 61