DigiTrace 920 Series Heat Trace Controller - Pentair Thermal ...

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a method to do preventative maintenance on the contactor according to the manufacturer’sspecifications. The count value is written to the controller’s nonvolatile memory once every 24hours or whenever any maintenance data is reset by the user.Procedure: The CONTACTOR CYCLE COUNTER may be reset to zero using the optional 920Operator Console or a communicating device.IMPORTANT:• Once the CONTACTOR CYCLE COUNTER reaches 999,999,999 it stops counting.• The CONTACTOR CYCLE COUNTER is only indicated if the SWITCH CONTROL MODE is set toeither DEADBAND or PROPORTIONAL AMBIENT CONTACTOR.4.3.4 TIME IN USEPurpose: The purpose of this feature is to indicate the total hours of controller use since its initialoperation. It may be useful to log the amount of time a controller has been in service for thepurposes of maintenance planning or reliability testing. The value of this accumulator is writtento the controller’s nonvolatile memory once every 24 hours or whenever any maintenance data isreset by the user.Procedure: The IN USE hours accumulator can be reset to zero using the optional 920 OperatorConsole (V3.11+) or a communicating device.IMPORTANT: The IN USE hours accumulator value will roll over to zero when the upper limit of theaccumulator has been exceeded. This limit is 4,294,967,295 hours for V3.00, and 999,999,999 hoursfor V3.11 and up.4.3.5 TIME SINCE LAST RESETPurpose: This feature indicates the total hours of controller use since the last reset. It may beuseful to log the amount of time a particular controller has been in service since the last time thecontroller’s power was cycled for troubleshooting purposes.Procedure: The TIME SINCE LAST RESET hours accumulator can only be reset by cycling thecontroller’s power.IMPORTANT: The TIME SINCE LAST RESET will roll over to zero when the upper limit of 65,535hours has been exceeded.4.3.6 PEAK LOAD CURRENT (V3.11 AND UP)IMPORTANT: The PEAK LOAD CURRENT is not displayed on the optional 920 Operator Console.Purpose: This feature indicates the highest instantaneous load current measured since the lasttime the PEAK LOAD CURRENT was reset. This value is written to the controller’s nonvolatilememory once every 24 hours or whenever any maintenance data is reset by the user.Procedure: The PEAK LOAD CURRENT may only be reset to zero using a communicating device.4.3.7 PEAK GROUND-FAULT CURRENT (V3.11 AND UP)IMPORTANT: The PEAK GROUND-FAULT CURRENT is not displayed on the optional 920 OperatorConsole.Purpose: This feature indicates the highest instantaneous ground-fault current measured sincethe last time the PEAK GROUND-FAULT CUR-RENT was reset. This current value is written to thecontroller’s nonvolatile memory once every 24 hours or whenever any maintenance data is resetby the user.Procedure: The PEAK LOAD CURRENT may only be reset to zero using a communicating device.4.3.8 EXTERNAL INPUT STATUS (V3.11 AND UP)IMPORTANT: The EXTERNAL INPUT STATUS is not displayed on the optional 920 OperatorConsole.Purpose: This feature indicates the actual status of the external input regardless of the controller’sconfiguration. This can assist the operator who wishes to use the controller’s external input tomonitor the status of an external dry contact and pass this on to another device.Procedure: The EXTERNAL INPUT STATUS may only be viewed using a MODBUS-capablesoftware package.THERMAL MANAGEMENT SOLUTIONS EN-DigiTrace920series-IM-H56874 04/13 48 / 82
Section 5 – Control Modes5.1 IntroductionThere are several types of control modes in the controller. Some of these modes require furtherexplanation in order to fully understand and implement their operation.This section describes the control modes available in the HTC and how to set their associatedparameters.5.2 Switch Control ModesThere are four SWITCH CONTROL modes associated with the HTC. The following is an explanationof their implementation in the controller and the differences between them.5.2.1 PROPORTIONAL CONTROL (FOR USE WITH SSRS ONLY)Proportional control on the HTC is implemented as follows:When using SSRs to directly control the power applied to a trace circuit, the output may beswitched on/off very rapidly. The controller im-plements proportional temperature control on acycle-by-cycle basis (50 or 60 Hz power line cycle). This algorithm monitors the temperature of theheating circuit and compares it to the CONTROL SETPOINT temperature. If the temperature of thecontrol sensor is at or below the CONTROL SETPOINT temperature, power is applied to the tracewith a duty cycle of 100%—the controller output is full on. If the temperature sensed by the controlsensor is equal to or greater than the CONTROL SETPOINT temperature + the PROPORTIONALBAND setting, the controller output will have a duty cycle of 0%—the output will be off. Thetemperature of the control sensor is constantly monitored and the output duty cycle is adjustedproportionally according to where the temperature falls within the 0%–100% band.Proportional Control Temperature BandControl Sensor Temperatureduty CycleSetpoint + proportional band 0%Setpoint + proportional band/2 50%Setpoint 100%5.2.2 DEADBAND CONTROL (FOR USE WITH EXTERNAL CONTACTORS)Deadband control on the HTC is implemented as follows:When using the HTC in an application where the controller is used to open and close a contactor,proportional control cannot be used. In these cases a deadband control algorithm is used. Theoutput duty cycle is not controlled; instead, the output is either fully on or completely off. The usercan set the DEADBAND value. The controller monitors the temperature of the trace circuit andcompares it to the CONTROL SETPOINT temperature as in the proportional control. If the controlsensor temperature is above the CONTROL SETPOINT temperature by more than the DEADBANDvalue, the output is turned off. If the control sensor temperature falls below the CONTROLSETPOINT temperature the output is turned on. This is a simple control algorithm but it worksvery effectively in heat trace applications where the temperature of a traced system changesrelatively slowly.Deadband Control Temperature BandControl Sensor TemperatureOutput StateSetpoint + deadbandOffSetpointOnWhen the control sensor temperature is within the deadband, the output does not change itsstate. Also, when using deadband control a contactor is not allowed to toggle faster than every twoseconds. If an AC alarm with an alarm filter time greater than 0 is detected, the contactor will nottoggle until the alarm filter time has expired.THERMAL MANAGEMENT SOLUTIONS EN-DigiTrace920series-IM-H56874 04/1349 / 82
Page 6 and 7: Section I - Overview1.1 Controllers
Page 8 and 9: CSA C/US and c-ETL-us ApprovedThe 9
Page 10 and 11: 1.5.1 ENCLOSURE ASSEMBLYEnclosure A
Page 12 and 13: The user may want to consider enclo
Page 14 and 15: Temperature SensorsTerminal No.Poin
Page 16 and 17: 2.7.6 INPUT POWERThe 920 controller
Page 18 and 19: Section 3 - Programming and Configu
Page 20 and 21: 3.5.2 ALPHANUMERIC TAG ASSIGNMENTPu
Page 22 and 23: Range: 0.3 to 100.0 amps(CURRENT TU
Page 24 and 25: 3.5.15 TS 1 HIGH LIMIT CUTOUTPurpos
Page 26 and 27: IMPORTANT:• Auto-cycling should a
Page 28: 3.6 Common Controller SetupThis is
Page 31 and 32: • This alarm must be enabled and
Page 33 and 34: Procedure: Enable or disable the al
Page 35 and 36: • If the user resets an alarm whi
Page 37 and 38: efore the corresponding alarm will
Page 39 and 40: the overcurrent trip limit and the
Page 41 and 42: the 920 control module, these param
Page 43 and 44: 3.10 Operator Console Functionsbut
Page 45 and 46: eset. All load-shedding parameters
Page 47: interface.IMPORTANT: The controller
Page 51 and 52: 5.3 Load Shedding Control ModeLoad
Page 53 and 54: Section 6 - Troubleshooting6.1 Oper
Page 55 and 56: If the bounce or instability is exc
Page 57 and 58: 6.3 Common Alarms—What to look fo
Page 59 and 60: Section 7 - Maintenance7.1 Operator
Page 62 and 63: Appendix B Typical Enclosure Dimens
Page 64 and 65: B.3 Four-Point Assembly #10160-1254
Page 66 and 67: B.5 Twenty-Point Assembly #10160-04
Page 68 and 69: C.1.2 100Ω NICKEL IRON RTD WIRINGC
Page 70 and 71: C.3 Communication Wiring C.3 Commun
Page 72 and 73: C.5 External Input/Output Port Wiri
Page 74 and 75: Appendix E 100 Ω Platinum RTD Tabl
Page 76 and 77: Appendix G Factory Default/Configur
Page 78 and 79: Other Alarms Configuration Sub-Menu
Page 80 and 81: Other Alarms Configuration Sub-Menu
Page 82: WWW.THERMAL.PENTAIR.COMNORTH AMERIC

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