
Example D4 - Process Temperature Control - Mechanical Relays
Extremely versatile, the TCM18 can be configured with RM-6 mechanical relay out-
put options. This option is often selected in high heat output tracing applications
where either high current or high voltage switching is required. One such tracing ap-
plication might be the temperature maintenance of a long sulfur transfer line. Typical
tracing design requirements are listed as follows:
Heater Cable Mineral Insulated Series Cable
Voltage Switched: 277 Vac
Current Switched: 49A
Sulfur Maintain Temperature: 282
◦
F (139
◦
C)
Sulfur Freeze Point: 260
◦
F (127
◦
C)
Sulfur Congeal Point: 320
◦
F (160
◦
C)
The TCM18 control module with pipe sensing RTD’s could be typically as shown
below:
Control Parameter Setting
Controller Configuration Single RTD Pipe Sensor
Control Method On/Off
Maintain Temperature 282
◦
F (139
◦
C)
Control Band 9
◦
F (5
◦
C)
High Alarm Temperature 300
◦
F (149
◦
C)
Low Alarm Temperature 260
◦
F (127
◦
C)
Having set in these values as well as the appropriate other limit/control values, the
following typical control can be achieved.
85 PN 50316_0514
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