Programming CM-2201
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©2015 Nelson Heat Tracing Systems
www.nelsonheaters.com GA2497 Rev. 2
7.2.9 Auto Test Cycle
This value sets the frequency at which the Auto Test Cycle is
activated. Auto Test is a feature that exercises the system
by automatically applying power to the heater at specified
time intervals. If an alarm condition is detected during this
period, the Auto Test Alarm is activated and an “ALARM
DURING AUTO TEST” message is added to the System Status
messages. This is a latching alarm. To clear the alarm,
locate the alarm message in the Alarm Menu and press
[ENTER]. To disable this feature, set the value to “Off”. The
Auto Test Cycle does not operate if heater is forced off for
any reason, including ground fault trip. Auto Test decreases
maintenance by providing an early warning of problems that
would otherwise go undetected until the heater was needed.
1. Display Mode: Advanced
2. Range: 1 to 720 hours, Off
3. Default: 24 hours
7.2.10 RTD Operation
This selection determines how the control temperature is
utilized by the RTD inputs.
In One RTD Mode, the temperature is based on the
measured temperature from RTD-A.
In Backup Mode, control temperature is based on RTD-A. If
for any reason RTD-A fails, then RTD-B takes over.
In Average Mode, the control temperature is based on the
average of RTD-A and RTD-B measured temperatures.
In Lowest Mode, control temperature is based on the lowest
of the two temperature measurements.
In Highest Mode, control temperature is based on the
highest of the two temperature measurements.
In High Temperature Cutoff Mode, control temperature is
based on RTD-A, but if the temperature from RTD-B exceeds
the high temperature alarm, the heater is turned Off and a
high temperature alarm is activated. The High Temperature
cutoff mode will operate in One RTD mode if the high
temperature alarm is turned Off.
7.2.10 RTD Operation Continued
Functions requiring two RTDs to operate, such as Average,
Lowest, Highest and High Temperature Cutoff, will operate
in One RTD mode if one of the two RTDs fail.
1. Display Mode: Advanced
2. Range: One RTD, Backup, Average, Lowest, Highest,
High Temperature Cutoff
3. Default: One RTD
4. Restrictions: Message does not exist if Maintain
Temperature is set to Off.
7.2.11 RTD Failure Mode
This selection sets the controller’s fail-safe mode. The
controller detects if RTD-A has failed and will use RTD-B if
available. If RTD-B is not installed or has also failed, the
heater will be set to its fail-safe state as selected in this
mode. For freeze protection where there is no hazard from
overheating, you may select “On” to operate the heater
continuously and prevent freeze up.
For processes where there is a potential hazard from
overheating, you may select “Off”, to de-energize the circuit
until one of the RTDs becomes available.
1. Display Mode: Advanced
2. Range: On, Off
3. Default: Off
4. Restrictions: Message does not exist if Maintain
Temperature is set to Off.
7.3 Program – System Setup
7.3.1 System Setup
This message displays the name of the sub-menu when
entered.
1. Display Mode: Advanced
2. Range: N/A
3. Default: N/A
7.3.2 Password
This selection determines if password protection is required
for programming changes. The display will show “Disabled”
if program access is currently enabled, and show “Enabled”
if program access is currently disabled.
1. Display Mode: All
2. Range: Enabled or Disabled
3. Default: Enabled
