Pentair 920 Series - Page 26

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EN- Raychem920series-IM-H5687405/15
INDUSTRIAL HEAT TRACING SOLUTIONS
IMPORTANT:
• Auto-cyclingshouldalwaysbeenabledfornormaloperation.Disablingthisfeatureshouldonly
be required where the HTC system is monitoring a circuit exercised by some other device or
means. Although this function defeats temperature control and forces output on, the controller
will continue to adjust the output for protection purposes or power limiting (SSR option only).
• Auto-cyclingisinhibitedifthecontrollerisintheloadsheddingmode.Seesection5.3
on page 52.
• Ifauto-cyclingisenabled,theHTCwillalwaysautocyclefor10secondswhenpowerisinitially
applied.
• Ifauto-cyclingisenabled,TSFAILMODE=OFFandallthecontroltemperaturesensorshave
failed, the HTC will still perform an autocycle.
• Ifanalarmcondition,withanalarmfiltertimegreaterthan0,appearsduringtheauto-cycling,
then the autocycle may be extended (past the 10 seconds) until the alarm filter time has
expired.
3.5.24 AUTOCYCLE TIME INTERVAL
Purpose:AUTOCYCLEINTERVAListhenumberofhours/minutesbetweensuccessiveheating
circuitintegritytestsdependingontheAUTOCYCLEUNITSspecified.
Range: 1 to 240
Procedure:SettheAUTOCYCLEINTERVALtothedesiredtimeperiod.
IMPORTANT:
• Whenusingproportionalambientcontactormode,theCYCLETIMEsettingshouldbelessthan
theAUTOCYCLEINTERVALotherwiseau-to-cyclingcouldaffectthedutycycle.
• IfanACALARMbecomesactiveduringanautocycle,buttheAUTOCYCLEINTERVALexpires
prior to the corresponding ALARM FILTER time, then auto-cycling will continue until the
ALARM FILTER time has elapsed.
• FortheearliestpossiblealarmingofheatingcircuitproblemstheAUTOCYCLEINTERVAL
should be set to a small value.
3.5.25 AUTOCYCLE TIME UNITS
Purpose: The autocycle time units parameter allows selection of minutes or hours for the
AUTOCYCLEINTERVALsetting.
Setting: HOURS or MINUTES
Procedure:SettheAUTOCYCLEUNITStothedesiredtimeunits.
3.5.26 INHIBIT CONTROL (V3.00 ONLY)
Purpose: This feature allows the HTC’s EXTERNAL INPUT to override the controller’s temperature
control and force the output switch off. This is especially useful when the user wishes to turn a
controller or a group of controllers off over the summer months, during maintenance, or when a
line is flowing and does not require heating.
Setting: ENABLE or DISABLE
Procedure: Enable or disable the INHIBIT CONTROL for the control point being programmed.
IMPORTANT:
• TheEXTERNALINPUTmustalsobeprogrammedasINHIBITbeforethisparametercanbeset.
See section 3.6.3 on page 29 for further details.
• Iftheautocyclefeatureisenabled,itwillcontinuetofunctionevenwhentheINHIBITmodeis
active.
• Fail-safemodeisinactiveiftheINHIBITmodeisactive.
• BothoftheLOWTSALARMSareinactiveiftheINHIBITmodeisactive.
3.5.27 OVERRIDE SOURCE (V3.11 AND UP)
Purpose: An override signal can be sent to the HTC from one of two sources. This override signal
can be used to override the controller’s temperature control and force the output switch off or on.
This is especially useful when the user wishes to turn a controller or a group of controllers off over
the summer months, during maintenance, or when a line is flowing and does not require heating.