Emerson Rosemount 6888A, Reference Manual

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3.7 Startup
The transmitter begins operation when the signal wiring is connected and heater power is
supplied to the transmitter. First power the AC line voltage to the heater and then power
the 24 Vdc power/signal loop for the transmitter electronics.
The O
2
probe takes approximately 45 minutes to warm up to the 736 °C (1357 °F) heater
setpoint. The 4-20 mA signal remains at a default value of 3.5 mA through this warmup
period. Once warm, the O
2
reads oxygen, and the 4-20 mA signal's reading is based on the
default range of 0-10% O
2
.
3.7.1 Error conditions
If there is an error condition at startup, an alarm message is displayed. Refer to Chapter 4 to
determine the cause of the error. Clear the error and cycle power. The %O
2
and
temperature display should return without the alarm message.
Configuration, startup, and operation
Reference Manual 75