Section 6 - Troubleshooting; Operator Checks; Common Problem Areas - Pentair 920 Series Installation, Operating And Maintenance Instructions

seCtIon 6 – troubLeshootInG

6.1 operator CheCKs

6.2 Common probLem areas

INDUSTRIAL HEAT TRACING SOLUTIONS
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 controller
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
correctly for the application. If the configuration is correct, return the controller to Pentair
Thermal Managament for evaluation.
Important: If the controller does not operate properly and is being returned to Pentair
Thermal Managament for service, information must be provided as to why the unit was removed
from service. Contact the Pentair Thermal Managament 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.
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 pro-gramming 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
installation 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
controller. 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 common
(RED) lead of the RTD at the controller. This should be between 60 Ω and 330 Ω depending on
the temperature and the lead resistance. See Appendix D on page 74 or Appendix E on page 75.
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