Example: Transmit temperature, control a chiller, and provide an over-temperature alarm.
Application: Transmit temperature of a fermentation tank as a 4-20 mA signal from 15°C to
35°C. Turn on a chiller when the temperature reaches 28°C. Turn off the chiller when the tem-
perature is below 24°C. Alarm temperatures over 30°C. The sensor is a Type K thermocouple.
Solution:
• Jumper signal conditioner for Type K thermocouple.
• Under “Input+Display” tab, set Mode to Thermocouple, range to “K deg C”, Resolution to
0.1 deg, and “50/60 Hz Line Freq” to 60 Hz to reject 60 Hz noise.
• Under “Relay Alarms” tab, select “Span Hysteresis” with a setpoint of 28.0°C and a devia-
tion of 4°C for Alarm 1, which will control the chiller. Select a setpoint of 30.0°C for Alarm
2, which will be used to alarm over-temperatures.
• Under “Analog Out” tab, set Range to “4-20mA Current”, “Lo Range Reading” to 15.0°C and
“Hi Range Reading” to 35.0°C.
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