CM-2201 General Operation
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©2015 Nelson Heat Tracing Systems
www.nelsonheaters.com GA2497 Rev. 2
5.1 Display
The CM-2201 utilizes a 2 line x 16 character
alphanumeric display, viewable from the front keypad. The
top line is reserved for the function or operation and the
bottom line displays the value range.
5.2 Keypad
The keypad is touch sensitive. The operator must touch the
area on the main label and the controller will respond.
5.3 LED Functions
LED indicators will show the status of the respective
functions. The power LED will be illuminated when the
controller is connected to a source voltage. The heater LED
will be illuminated when voltage is applied to the heater.
The system LED will illuminate if there is an internal
hardware issue with the controller. The comm LED will
illuminate when the controller is sending data through
external communication. The alarm LED will flash when
there is a current active alarm condition; the alarm LED
will illuminate solid when an alarm was present, but is not
currently active.
5.4 Monitoring
By touching the “Actual” button, followed by an arrow, the
controller will display all the active parameters, one at a time.
5.5 Alarm Management
All the alarm(s) will be saved in the alarm log. If the alarm
is not active (alarm LED solid red), the Alarm LED can be
turned off by touching “Reset”, one alarm at a time. If the
alarm is active (alarm LED flashing red), the user cannot
reset the alarm.
5.6 Soft-Start Feature
The Soft-Start feature enables self-regulating cables to be
energized at low temperatures without causing excessive
load on the electrical system, and extends cable life by
reducing cable internal heating due to inrush currents. The
resistance of self-regulating cables decreases as these
cables get colder, which results in higher current draw.
5.6 Soft-Start Feature Continued
This can result in breaker trips if temperatures are very cold
and the installed length of cable is high. The Soft-Start
feature operates by initially only energizing the cable for a
very short period of time – while the current draw may be
high during this period, the period is usually short enough
to reduce average load on the electrical system. This short
energization period is repeated and eventually increased;
after a few minutes, the cable is usually warm enough such
that the resistance has increased and the current decreased
to the point where it can be continuously energized.
5.7 Current-Limiting Feature
The Current-Limiting feature operates similarly to the
Soft-Start in that it restricts the amount of time the cable
is energized during any given period, thereby reducing the
average current draw of the cable during that period. For
example, if a cable normally draws 8 Amps, but current
limit is set to 6 Amps, then the cable would be energized
only 75% of the time.
5.8 Ground Faults
Ground faults typically are the result of damaged or
improperly installed cables which allow current-carrying
conductors/surfaces/parts to be in contact with grounded
objects. For example, if a heating cable has been secured
to a pipe with a clamp, and if the clamp has been
overtightened, then the ground braid and/or the pipe may
come in contact with current carrying parts within the
cable. This would result in current leakage to ground
through the ground braid of the cable and/or the pipe itself.
This type of fault can eventually become serious, resulting
in overheating/fire/shock hazards. Current leakage to
ground can be monitored by electronic circuitry, and the SPC
can be programmed to either alarm or trip when leakage
current exceeds the specified maximum allowable amount.
