Peak Discrimination; Temperature Control Hardware Problems; Temperature Probe Open; Temperature Probe Shorted - ABB PGC2000 Operation And Service Manual

Peak Discrimination

Symptom: Discrimination is the non linear unequal dilution of hydrocarbons in the column train.
Typically the heavier components will tend to dilute more than the lighter components.
Cause: Discrimination is usually the result of a leak or incorrectly adjusted sample splitter. The leak
or split might cause more of the heavier components to be exhausted out the splitter vent or leak exit
than the lighter components; thus, disproportionate dilution. Perform Test Procedure 32 (Peak
Discrimination) to test for discrimination.

TEMPERATURE CONTROL HARDWARE PROBLEMS

The following alarm indicators help isolate hardware failures in the temperature controller.

Temperature Probe Open

Symptom: No heat to a specific temperature zone. Actual temperature as indicated in Manual
Temperature Control Mode indicates greater than 500 deg C for a specific zone. Other zones' actual
temperature indicate low or ambient. At the temperature board in electronics enclosure, all LED's are
off as the temperature control board shuts down.
Any one of the following alarm messages or conditions could be present:
On Background Screen
On Manual Temperature
Control Mode Screen
On Alarm Screen
Failure: The failure is most likely isolated to the zone indicating a temperature greater than 500 deg
C. The temperature sensor(s) is a 400 ohm platinum thermocouple probe. As the temperature of the
probe increases, its resistance value increases. As the temperature of the probe decreases, the
resistance decreases. The maximum temperature range measurable by the temperature controller is
500 degrees. An indication greater than 500 degrees corresponds to a high resistance value at the
sensor input. The greatest resistance possible is an open circuit to the sensor input or open probe or
connection. The least resistance would be a shorted probe or connection to the sensor input.
Cause: The sensor to the zone input has possibly opened, or is no longer connected to the sensor
input. Perform Test Procedure 21 (Open Temperature Sensor).

Temperature Probe Shorted

Symptom: No heat to a specific temperature zone. Actual temperature as indicated in Manual
Temperature Control Mode indicates less than -200 deg C for a specific zone. Other zones' actual
temperature indicate low or ambient. At the temperature board in electronics enclosure, all LED's are
off as the temperature board shuts down.
6-12
***ALARM:*** (flashing)
Zone (#) (flashing)
*Temp Bd Alarm* (flashing)
Temperature Board:
*Zone Specific
*Analysis Shutdown
*** TEMP ZONE (#) Alarm ***
*Overtemp
*Reasonableness Test
*Probe Open/Shorted or TC Faulty
*High Temp
2000-OSM, F1