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Nelson™ Heat Trace CM3 Circuit Management System
Nelson™ Heat Trace™ CM3 Circuit Management System
Nelson™ Heat Trace CM3 circuit management system provides a compact, tightly integrated, factory assembled/tested solution for high density plant locations.
The unit is based on a standard PLC platform, specifically integrated for use with electric heat trace systems. The CM3 provides temperature monitoring and control of the trace heating system. It automatically checks the health of the trace heating system. Negative trends are noted on a maintenance pending list, while more severe problems are removed from service and alarmed.
Nelson™ Heat Trace CM3 Circuit Management System


Certifications and Compliances
ETL Listed to UL and CSA Standards: Hazardous (Classified) Locations
Class I, Division 2, Groups A, B, C, D; Temperature Code T4 (+135 °C) -P option only
NEMA 4, 4X and 12
Heat Trace Load
24 Amps @ 277 Vac (-R2 option); 24 Amps @ 600 Vac (-C option)
Ambient Temperature
-20 °C to +40 °C (-4 °F to +104 °F)
Color LED, CFL 75,000h. Operator interface Analog touch pad (1,024 x 1,024). Program by channel or global. Temperature in °F or °C
Control Power Input
120 or 240 Vac, single-phase
Control Temperature
Set point -328 to +1392 °F range, adjustable
High and low temperature alarms are adjustable. Ground fault and trip alarms are 1-500ma, adjustable. Current high and low alarms are 1-30 Amps, adjustable
Auto-Test Cycle
1-720 hrs, adjustable
Predictive Maintenance Log
Predictive log trigger values are adjustable
RTD, 100 ohm, platinum, 3-wire
Alarm Contacts
Common for all alarms. Separate alarm contact for ground fault only
Serial RS-485, Modbus™ RTU protocol (-EC option); Ethernet TCP/IP Modbus™ RTU protocol (-NC option)


  • Temperature control: An RTD based temperature control function optimizes energy consumption, while maintaining tight temperature control on your process piping. High and low temperature alarms will alert you to any upset conditions that could cause probl
  • Heat Trace ground fault protection: The system provides continuous monitoring of ground fault conditions with each circuit, eliminating the need for expensive ground fault protection branch circuit breakers. Separate values can be inserted for alarm and
  • Predictive maintenance system: Ground fault and load current values are compared to earlier values. Adverse trends in a trace heater will get that circuit put on a maintenance log alert system. This log allows the limited maintenance resources to be opti
  • Heat Trace power output monitoring: Adjustable high and low load current alarms for each heat trace circuit provide a constant monitor of the power output of each heat tracer. A low current alarm can identify the loss of a heater segment before the pipe
  • Automatic testing: The system will continuously test the system, even when it is not in use. This allows any problems to be identified as they occur, rather than allowing problems to cascade over a long period. The unit turns each circuit on at selected
  • Features include optimized process control temperatures, energy conservation, elimination of separate ground fault branch circuit breakers, automated trace heater monitoring, predictive maintenance monitoring
  • Interface: Color touch screen operator interface. Displays all alarms. Displays actual temperature. Displays heat trace circuit status- on or off. Displays actual heat trace ground fault and load currents. Displays all set points
  • Global programming: Intuitive, easy to navigate. Automated monitoring. Testing of heat trace circuit - voltage, current, ground fault. Predictive maintenance, trend monitoring of heat trace