Section 8-Troubleshooting; Operator Checks; Common Problem Areas - nvent 910 Series Installation, Operating And Maintenance Instructions

SECTION 8—TROUBLESHOOTING

8.1 OPERATOR CHECKS

8.2 COMMON PROBLEM AREAS

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IMPORTANT: If the controller does not operate properly and is being returned to nVent for
service, information must be provided as to why the unit was removed from service. Contact
the nVent customer service department for a Return Authorization form and number prior to
returning any units for repair.
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.
In order to determine if a fault is associated with the heat tracing, wiring or the controller, it
will be 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. Refer to the following sections for the appropriate topic.
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 it may be necessary to
return the controller to nVent for evaluation.
8.1.1 GETTING STARTED
In order to access the functions of the 910 Series HTC, use the Operator Console. If the
modem communications option is installed in the 910, the Model 780/GCC-9000 Group
Communications Controller may also be used to access controller parameters. Refer to the
GCC User Manual for operational details.
The HTC may 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.
8.2.1 RTDS
RTD failures after installation can generally be attributed to incorrect wiring or improper
installation of the sensor. Troubleshooting of these failures is a very simple procedure if the
proper steps are undertaken in the correct order. Some specific RTD problems and the correct
methods for troubleshooting are outlined as follows.
1. TS Failure Alarm(s)
If the HTC controller indicates a failure of an RTD:
• Ensure that the RTD is a 3-wire 100 ( Platinum Type (for V3.00). For V3.11 and up ensure that
the TS TYPE setting matches the RTD being used.
TURN THE POWER TO THE CONTROLLER OFF 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 (should be between 60 and 330 Ω depending
on the temperature and the lead resistance. See Appendix E or Appendix F).
• Verify that the RTD is wired correctly—the heat tracing controllers will always be terminated
in the order: source (WHT), sense (WHT), common (RED). When wiring to the 910, the
terminals are marked as follows: