Programming
CM-2201/CM-2202
©2018 Nelson Heat Tracing Systems
www.nelsonheaters.com
GA2497 Rev.6
12
7.2.9
Soft Start Mode
This function ramps the heater output from Off to nominal
current of the heater over the set soft start cycle
time. It is useful for reducing inrush currents of self-
regulating heaters. At the end of the soft start cycle time,
the load will no longer be controlled by the soft start
function.
1.
Display: Advanced
2.
Range:10 to 999 seconds, Off
3.
Default: Off
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 Cut off 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 cut off mode will
operate in one RTD mode if the high temperature alarm
is turned Off.
Functions requiring two RTDs to operate, such as Average,
Lowest, Highest and High Temperature Cut off, 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 Cut off
3.
Default: One RTD
Restrictions: Message does not exist if Maintain
Temperature is set to Off.
7.2.11
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 to720 hours, Off
3.
Default: 24 hours
7.2.11
RTD Failure Mode
This selection sets the controllers 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 RTD’s becomes
available.
1.
Display Mode: Advanced
2.
Range: On, Off
3.
Default: Off
Restrictions: Message does not exist if Maintain
Temperature is set to Off.
7.2.12
Alarm Contact
This selection sets the operating mode of the external
alarm indicator.
By setting the contacts to NC, these contacts
will be open when there is no power applied to the unit (this
can be useful for signaling loss of power to the unit) OR there is
an active alarm OR there previously was an active alarm that
has not been acknowledged.
The alarm contacts function as follows:
1.
Display Mode: Advanced
2.
Range: Normally Open, Normally Closed
3.
Default: Normally Open
