Rosemount 2081 pH, Инструкция по эксплуатации

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SECTION 7.0 THEORY OF OPERATION
GENERAL
This section is a general description of how the transmitter operates. This section is for those users
who desire a greater understanding of the transmitter’s operation.
The measurement of the process’ pH is accomplished by the use of two electrodes within the sensor. The glass
electrode is pH sensitive and generates a high impedance millivolt potential directly proportional to the process
pH. The reference electrode is a second half cell that completes the circuit via a liquid junction. The high imped-
ance signal is preamplified at or near the sensor to allow a stable noise-free signal that can be transmitted up to
1000 feet.
The transmitter also measures the process temperature via a platinum 100 ohm RTD imbedded in the sensor.
Advanced circuitry is used to eliminate errors due to changes in cable resistance. The transmitter uses this tem-
perature measurement to compensate for the changes in the sensor’s millivolt output caused by process tem-
perature change.
MODEL 2081 pH SECTION 7.0
THEORY OF OPERATION