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Section 6 Troubleshooting
6.1 Operator Checks
Upon receipt of the controller, or to check the controller for an indication of normal operation,
follow the operational procedures shown below. These procedures are designed to familiarize
the operator with the controller and to provide an understanding of its operation.
To determine if a fault is associated with the heat tracing, wiring or the controller, it is necessary
to troubleshoot the wiring and tracer circuit. If the fault remains, remove power from the con-
troller and exchange it with another controller. This may require some reprogramming of the
new
HTC.
If the fault clears, exchange the controller on another circuit to determine if the fault moves with
the controller. If the fault moves with the controller, verify that the
HTC has been configured cor-
rectly for the application. If the configuration is correct, return the controller to Tyco Thermal
Controls for evaluation.
Note: If the controller does not operate properly and is being returned to Tyco Thermal Controls
for service, information must be provided as to why the unit was removed from service. Contact
the Tyco Thermal Controls customer service department for an authorization form and number
prior to returning any units for repair.
6.1.1 GETTING STARTED
To access the functions of the 920 Series
HTC, use the optional 920 Operator Console. If the
modem communications option is installed in the 920 control module, the Model 780/GCC-9000
Group Communications Controller may also be used to access controller parameters. Refer to
the operating manual for the particular device that you are using for operational details.
6.2 Common Problem Areas
The HTC can be used as an effective troubleshooting tool to pinpoint problem areas of heat trace
circuits. Described below are a few of the more common problem areas, their symptoms, and
parameters to check to determine the actual faulty portion of the heat trace circuit.
6.2.1 CONTROL POINT A VERSUS CONTROL POINT B
Remember that the 920 series controller is a two-point device!
One of the most common errors is to confuse settings, displays, or alarms for one control point
with the second control point. When programming or troubleshooting, always confirm that you
are referencing the control point of interest—either Point A or Point B.
6.2.2 RTDS
RTD failures after installation can generally be attributed to incorrect wiring or improper installa-
tion of the sensor. Some specific
RTD problems and troubleshooting methods follow.
1. TS Failure Alarm(s)
If the HTC controller indicates a failure of an
RTD:
• Ensure that the
RTD is a 3-wire 100 Ω Platinum Type (for V3.00). For V3.11 and up ensure
that the
TS TYPE setting matches the RTD being used.
• Turn off the power to the controller before proceeding!
• Disconnect the
RTD wiring from the input terminals.
• Measure the
RTD’s resistance between the source (WHT) and sense (WHT) leads at the con-
troller. It should not exceed 40 Ω. Excessive lead resistance will cause a
TS FAILURE ALARM
and must be corrected. Look for loose terminals, excessive lead length, or insufficient wire
gauge and correct as necessary.
• Measure the
RTD’s resistance between the source (WHT) or sense (WHT) lead and the com-
mon (
RED) lead of the RTD at the controller. This should be between 60 Ω and 330 Ω depend-
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