Pentair 920 Series Installation, Operating And Maintenance Instructions page 23

INDUSTRIAL HEAT TRACING SOLUTIONS
3.5.12 temperature sensor ControL mode
purpose: The TS CONTROL MODE allows the selection of one of eleven possible temperature
control modes for the controller. The different modes allow redundant fail-safe temperature
sensing, averaging, or minimum maintain temperature control.
setting: Select one of the following eleven possible modes:
Control ts and description
CONTROL USING TS 1, FAIL OFF/ON
CONTROL USING TS 1, FAIL TO TS 2
CONTROL USING TS 2, FAIL OFF/ON
CONTROL USING TS 2, FAIL TO TS 1
CONTROL ON AVERAGE, FAIL OFF/ON
CONTROL ON AVERAGE, FAIL TO GOOD
CONTROL ON LOWEST, FAIL OFF/ON
CONTROL ON LOWEST, FAIL TO GOOD
The following are only available in V3.11+:
CONTROL USING EXT. INPUT, FAIL OFF/ON
CONTROL USING EXT. INPUT, FAIL TO TS 1
CONTROL USING EXT. INPUT, FAIL TO TS 2
Where OFF/ON = Controller's output switch turned OFF or ON as determined by the TS FAIL MODE.
example: With a TS CONTROL MODE of CONTROL ON AVERAGE, FAIL TO GOOD, the controller
will measure both sensors (TS 1 and TS 2), averaging the two temperature value;, display the
results; and cycle the heater ON or OFF to maintain the CONTROL SETPOINT temperature. This
is the primary control mode. If either sensor should fail, the controller will transfer control to the
remaining "good" sensor and generate the appropriate TS 1 or TS 2 FAILURE ALARM (assuming
that the alarm is enabled). The temperature will now be maintained based on this measured value.
If the remaining good sensor fails, the controller will turn the heater OFF or ON as determined
by the TS FAIL MODE setting. The appropriate TS 1 or TS 2 FAILURE ALARM will be also be
generated.
procedure: Select the control mode that best suits the application.
Important:
• Ensure that TS FAILURE ALARMS are enabled. See sections 3.7.1 on page 32, 3.7.4 on page 32,
and 3.7.10 on page 34 for a complete explanation of RTD failure detection in the HTC.
• If the selected TS CONTROL MODE uses the EXTERNAL INPUT then the EXTERNAL INPUT
must be set to TEMPBUS™ (see Section 3.6.3). Also, the CONTROL TS FAILURE ALARM is non-
latching in this mode.
• Fail safe mode is always disabled if the TS CONTROL MODE = EXT. INPUT, FAIL OFF/ON.
3.5.13 ts 1 type (v3.11 and up)
purpose: This parameter specifies the type of RTD that is connected to the HTC's TS 1 input.
setting: 3-wire 100 Ω platinum or 2-(or 3-) wire 100 Ω nickel-iron (Ni-Fe)
procedure: Select the type of RTD that is connected to the TS 1 input.
Important: If a 2-wire 100 Ω nickel-iron (Ni-Fe) RTD is selected then the TS 1 LEAD RESISTANCE
must be entered manually (see section 3.5.14 on page 24).
3.5.14 ts 1 Lead resIstanCe (v3.11 and up)
(For Ni-Fe RTDs only)
purpose: This parameter specifies the lead resistance of a 2-wire nickel-iron RTD connected to
the HTC's TS 1 input.
range: 0 to 20.00 Ω
procedure: Measure the resistance of one of the nickel-iron RTD leads (from the RTD to the HTC's
TS 1 input) and use this value as the TS 1 LEAD RESISTANCE.
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