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4.0   3508 Dual Loop Cascade

4.0

3508 Dual Loop Cascade Control (if fitted)

4.1

Principle of Cascade Control

When cascade control is fitted, the Load Loop 3508 senses the temperature of the
workload, and the Element Loop 3508 senses the element temperature. Depending on
the oven or furnace model, the Load Thermocouple may be in a fixed position, or may
be movable. The Element Thermocouple is fixed in a predetermined position near the
heating elements. The Load Thermocouple should be placed as near as possible to the
work to be heated.

The Load Loop communicates with the Element Loop, calling for heat according to the
load temperature and the current program or set point. The Element Loop regulates the
heat according to element temperature and the requests from the Load Loop.

The element temperature could, in principle, vary between the furnace or oven
maximum and minimum, regardless of the working temperature of the load. In
practice, the cascade control system is configured to limit the element temperature to a
band around the load temperature, typically of ±10% of the set-point temperature.

The set point of the load loop, shown at the top of the display, can be adjusted by the
operator. The Element Loop, shown at the bottom of the display, should not be adjusted
by the operator & will automatically regulate the element temperature to achieve the
Load set temperature.

In a three-zone furnace for which the “three zone cascade” option has been ordered the
centre zone is a 3508 Dual Loop & separate end zone controls are fitted. The operator
sets the Load loop set point on the 3508 centre zone. The end zone controllers work
automatically & need no adjustment by the operator.

4.2

Operation of Cascade Control

The operator may ignore all the complications of the system, and program the Load
Loop according to the standard instructions for that controller. The home display shows
the load loop at the top of the display and the Element loop at the bottom. By pressing
the page key, separate views of load and element loops will be shown.

34

Summary of Contents for CARBOLITE GERO HTF 18/4

Page 1: ...Installation Operation and Maintenance Instructions 1800 C Chamber Furnace HTF Model 4 Litres 3508 Controller HTF 18 4 3508 Controller MEN HTF1804 001_3508 02 08 2019 ...

Page 2: ... the Heating Elements 9 2 4 Electrical Connections 10 2 5 Power Supply Notes 11 3 0 3508 Controller 12 3 1 PID control 12 3 2 3508P1 12 3 3 3508P10 12 3 4 3508P25 12 3 5 Basic Operation 13 3 5 1 Controller Layout 14 3 5 2 Keys 14 3 6 Quick Start Guide 14 3 6 1 Operation as a simple controller 14 3 6 2 Changing the Setpoint 14 3 6 3 Resetting the programmer 15 3 6 4 Understanding User Levels 15 3 7...

Page 3: ...10 Temperature Controller Replacement 30 3 11 Controller Navigation Diagrams 30 3 11 1 Operator Level 1 No Program Running 31 3 11 2 Operator Level 1 Program Running 32 3 11 3 Supervisor Level 2 33 4 0 3508 Dual Loop Cascade Control if fitted 34 4 1 Principle of Cascade Control 34 4 2 Operation of Cascade Control 34 4 3 Bypassing Cascade Control 38 4 4 3508P1 Element Loop Loop 2 38 4 5 Caution 38 ...

Page 4: ... Switch 49 7 2 3 Other Electrical Components 49 7 2 4 Element Glaze 50 7 3 Calibration 50 7 4 After Sales Service 50 7 5 Recommended Spare Parts and Spare Parts Kit 50 7 6 Power Adjustment Controller 50 7 7 Power Adjustment Thyristor 51 7 8 Low Voltage Compensation 51 8 0 Repairs and Replacements 52 8 1 Safety Warning Disconnection from Power Supply 52 8 2 Safety Warning Refractory Fibre Insulatio...

Page 5: ...alysis 60 A Furnace Does Not Heat Up 60 B Product Overheats 61 10 0 Wiring Diagrams 62 10 1 Single Phase 208 V 220 240 V 62 11 0 Fuses and Power Settings 64 11 1 Fuses 64 11 2 Power Settings 64 12 0 Specifications 66 12 1 Environment 66 5 ...

Page 6: ...ht glows or flashes to indicate that power is being supplied to the elements 1 2 Warning Symbols DANGER Electric shock Read any warning printed next to this symbol WARNING Risk of fatal injury DANGER Hot surface Read any warning printed next to this symbol WARNING All surfaces of a product may be hot DANGER Read any warning printed next to this symbol FAULT read any information printed by this sym...

Page 7: ...Caution Double Pole Neutral Fusing 7 1 0 Symbols and Warnings ...

Page 8: ...ool ASW For precautions and advice on handling this material see section 8 2 2 2 Siting and Setting Up Place the product on a level surface in a well ventilated area Site away from other sources of heat and on a non flammable surface that is resistant to accidental spillage or hot materials The surface on which the equipment is mounted should be stable and not subject to movement or vibrations The...

Page 9: ... that any vents on the top of the product are clear of any obstruction Always ensure all cooling vents and cooling fans if fitted are clear of any obstruction 2 3 Fitting the Heating Elements Please refer to the Element Installation and Replacement in section 8 0 Wear eye protection when handling the heating elements The molybdenum disilicide elements are EXCEPTIONALLY FRAGILE and are packed separ...

Page 10: ... by removal of the left hand end side cover see section 8 3 The electrical supply cable must be properly connected and fitted with an appropriate strain relief at the entry to the case The electrical supply cable should be wired to an isolator or fitted with a line plug The isolator must be within easy reach of the operator or the line plug must be easily removable and on a lead not exceeding 3 m ...

Page 11: ...and 8 10 It is possible to alter the voltage within any of the ranges above by reconnecting the incoming cable to the transformer to the appropriate primary tapping The tappings are 208 220 230 240 V or 380 400 415 V and are labelled on the primary side of the transformer see section 8 10 It is also necessary to adjust the setting of the thyristor stack see section 8 4 Examples l to alter a furnac...

Page 12: ... give excellent temperature control when properly set This controller can store 10 programs of up to 50 segments each Programs can be operated individually or linked by a Call parameter as sub programs or to form single long programs The 3508P10 can also be used as a simple temperature controller 3 4 3508P25 The 3508P25 is a digital temperature controller which uses PID algorithms to give excellen...

Page 13: ...or C Not Used D Runs Holds Resets the current program E Page F Scroll G Down H Up I Power Output Percentage J Program Setpoint Temperature PSP when a program is running K Setpoint Temperature SP when basic controlling L Measurement Temperature 13 3 0 3508 Controller ...

Page 14: ... Quick Start Guide 3 6 1 Operation as a simple controller When switched on the controller goes through a short test routine and then shows the measured temperature Below it the setpoint temperature SP and percentage of power output The controller will immediately attempt to reach the set temperature and maintain it This will cause the product to heat as quickly as possible which may not be appropr...

Page 15: ...ly when a program is operating To pause the program press RUN HOLD To stop the program and return to simple controlling reset press RUN HOLD for 2 seconds When the program ends the programmer will either Automatically reset to operation as a simple controller Dwell at the last temperature of the program with the RUN indicator flashing until the operator presses RUN HOLD for 2 seconds to manually r...

Page 16: ... now in level 1 3 7 Setting Up Controller Before using the controller or during its lifetime certain parameters may have to be set depending on specific requirements To do this the controller must be set to Supervisor Level 2 see Controller Navigation Diagrams 3 7 1 Maximum output power setting Press page until Control Output Hi is displayed Press up or down to adjust the value Depending on the pr...

Page 17: ...e End type Dwell For the P10 and P25 programs can be linked together using a Call segment However a lower number program can not be called and a program can not be ended with a call segment A program can be ended in four ways 1 With End segment set to S OP the power to the elements is turned down to 0 no matter what the Setpoint temperature is 2 With End segment set to Reset and the Setpoint tempe...

Page 18: ...eating only High Applies to cooling only Band Applies to both heating and cooling Off Holdback is switched off To set the holdback type press page twice then press scroll until the display shows Holdback Type for each segment and press up or down to set The default setting for holdback is OFF 3 8 3 Wait Segments Wait prevents the program proceeding to the next segment in a similar way to holdback ...

Page 19: ...times to get to the programming page the display will show ProgEdit 1 Program number On P10 or P25 models press up or down to select a new program number The display will show that new programs have only one segment Holdback Value Press scroll until the display shows Holdback Value If required Press up or down to set a value This value will be used in any segment where a Holdback Type is set Ramp ...

Page 20: ...ows Wait For Press up or down to select PrgIn1 PrgIn2 PrgIn1In2 PrgIn1orIn2 PVWaitIP GoBack to segment number visible only for GoBack segments Press scroll until the display shows GoBack Seg Press down to select a segment number to go back to GoBack Cycles visible only for GoBack segments Press scroll until the display shows GoBack Cycles Press up or down to set a value Call Cycles Visible only fo...

Page 21: ...o select a program Press page until Program Status Reset appears Press scroll then up or down to select a program number To operate the program Press RUN HOLD or Press scroll until the cursor moves to Reset Press up or down to select Run Run will be displayed 3 8 10 Program Status While a program is operating the home display shows 3 values l Top Measured temperature l Centre Program Setpoint PSP ...

Page 22: ...started again by pressing the RUN HLD button the HLD indicator will flash again if the measured temperature has not caught up with the program Programming note For P10 and P25 models other programs can be created or changed whilst the current program is operating 3 8 12 Power Failure Recovery If there is a power interruption to the controller during a program when power is restored the controller ...

Page 23: ...cally below 1 Turn the controller SP down to 0 by pressing down 2 Press page until Prog Segments Used is displayed On P10 or P25 models press up or down to select a new program number a program with only 1 segment 3 Press scroll until Holdback Value is displayed Default 0 degrees 4 Press scroll until Ramp Units is displayed Press up or down to set to Min 5 Press scroll until Cycles is displayed De...

Page 24: ...l until End Type is displayed Press up or down to select Reset 13 Press page and scroll together to return to the home display To run the program either press RUN HOLD or 14 Press page until Program Status is displayed 15 Press scroll until the cursor moves to the program status of Reset 16 Press to select Run 24 ...

Page 25: ...Program Example 2 The following sequence of entries creates and runs the program shown graphically below 1 Turn the Setpoint to 0 by pressing down 2 Press page until Prog Segments Used is displayed On P10 and P25 models press up or down to select a new program number a program with only 1 segment 3 Press scroll until Holdback Value is displayed Press up or down to set to 5 degrees 4 Press scroll u...

Page 26: ...am models Segment Type Rate Target SP 400 degrees Ramp Rate 2 0 degrees per minute Segment Type Step Target SP 200 degrees Segment Type Dwell Holdback High Duration 30 00 0 minutes Segment Type Call Call Prog next number Call Cycles 2 Finish the program with an End segment 11 Press scroll until Segment Type is displayed Press up or down to select End 12 Press scroll until End Type is displayed Pre...

Page 27: ...lue 5 C P10 and P25 only Program 3 Example 3 9 Controller Options As options can be ordered in a variety of combinations and for a variety of purposes exact instructions are not given here The full Eurotherm manual may be required to determine customer parameter settings To reveal or hide parameters in the controllers it is necessary to go into configuration mode a security code is needed Please c...

Page 28: ... together 1 4 6 6 8 20 Link together 3 9 2 Digital Communications RS485 If an RS485 option is supplied the furnace is fitted with two D sockets Connection between products is by straight cable as follows Product end of cable female 25 pin 9 pin RS485 Cable product to PC Computer end of cable 9 pin 25 pin female 2 3 3 2 Tx 3 2 2 3 Rx Com 7 5 _________________ 5 7 Com 3 9 3 Comms Address Typically t...

Page 29: ... customer requirements Remote input when specified may be switched on and off using the remote setpoint enable parameter in the controller level 2 if this was made available for a particular application In level 2 press page until REM SP Enable is displayed press up or down to select SP1 the normal controller setpoint or SP2 the remote input setpoint SPX will appear in the top left corner of the d...

Page 30: ...the controller wear an anti static wrist strap or otherwise avoid any possibility of damage to the unit by static electricity Refer to the detailed instructions supplied with the replacement controller Ease apart the two lugs at the side grip the instrument and withdraw it from its sleeve push in the replacement 3 11 Controller Navigation Diagrams The following diagrams detail how to navigate to t...

Page 31: ...1 No Program Running HD Home Display Controller identity when using more than one controller R O Read Only Black Progress Page Key White Return Scroll Key Visible Parameters depend on the Segment Type 31 3 0 3508 Controller ...

Page 32: ... Operator Level 1 Program Running HD Home Display Controller identity when using more than one controller R O Read Only Black Progress Page Key White Return Scroll Key See previous diagram Operator Level 1 No Program Running 32 ...

Page 33: ...y B Level 2 Locked before Pass Code entered L1 Level 1 Home Display Unlocked L2 Level 2 Home Display Black Progress Page Key See previous diagram Operator Level 1 No Program Running Hold Page Key for 3 seconds If configured Arrow Key 33 3 0 3508 Controller ...

Page 34: ...the load In practice the cascade control system is configured to limit the element temperature to a band around the load temperature typically of 10 of the set point temperature The set point of the load loop shown at the top of the display can be adjusted by the operator The Element Loop shown at the bottom of the display should not be adjusted by the operator will automatically regulate the elem...

Page 35: ...y A Home Display View B Load Loop View C Element Loop View The Element Loop should never be adjusted Note that the elements usually run at a higher temperature than the load 35 4 0 3508 Dual Loop Cascade ...

Page 36: ...does not reach the desired temperature or is slow in the final stages FF Trim can be increased a maximum of 10 is suggested Feed Forward View When attempting to control at very low temperatures it can become a problem to achieve stable control because of excessive power being supplied during heating The available power can be limited using the power limit parameter OP Hi make a note of the origina...

Page 37: ...Power Limit View 37 4 0 3508 Dual Loop Cascade ...

Page 38: ...rameter to Also note that cooling at low temperatures takes longer per degree than it does at high temperatures 4 5 Caution If the Load Thermocouple is removable leave it in the furnace or oven chamber whenever possible Operating with the Cascade Control active and with the Load Thermocouple in an unheated position such as lying on the work bench may cause the furnace or oven to heat up to its max...

Page 39: ... off power to the controller and other parts of the control circuit To operate the controller power must be supplied to the product and the instrument switch must be on If a time switch is included in the product circuit this must be in the ON position When an over temperature condition occurs the controller cuts the power to a contactor which in turn cuts power to the heating elements Power is no...

Page 40: ... with the over temperature set at 15 C above the furnace or oven maximum working temperature Press scroll twice view the present temperature as measured by the over temperature controller Press it twice the first press shows the temperature units C 5 2 4 Over Temperature Alarm If an over temperature condition occurs the OP2 indicator flashes and an alarm message 2FSH also flashes alternating with ...

Page 41: ...top sounding when the alarm is acknowledged as given in section 5 2 Note the alarm may sound during controller start up 5 4 Navigation Diagram HL Home List Page Key Black Progress OTSP Over Temperature Setpoint Scroll Key Dashed Through to other options AL Access List For factory access to list and parameters not available to the operator 41 5 0 2132 Over Temperature ...

Page 42: ...the over temperature controller according to the instructions supplied To switch the product off turn the instrument switch off The case cooling fans continue to operate Leave the fans on until the product cools to below 300 C If the product is to be left unattended isolate it from the electrical supply 6 2 Operator Safety This product incorporates a safety switch which interrupts the heating elem...

Page 43: ...ecessary to load or unload work at elevated temperatures keep the door open for as short a period as possible The insulation cools quickly and may crack through thermal shock The heating elements and the insulation are very susceptible to mechanical shock At all times operate the door gently to avoid mechanical shock Opening the door when the furnace is very hot can cause hot air to be sucked by t...

Page 44: ...o pesting Pesting can be seen as a yellowish crystal growth on the surface of the element It occurs when the element surface temperature is around 450 C and is caused by the air oxidising with the molybdenum in the element compound Under normal operating conditions above 800 C pesting is not a problem and can often be seen occurring naturally on the element terminals operating the furnace for prol...

Page 45: ...ed to high temperatures for a minimum length of time Failure to check the thermocouple regularly may result in overheating of the work and the furnace with consequential damage to both 2 The thermocouples fitted to these models give very low outputs below approximately 600 C and do not give accurate readings at low temperatures They may show a negative temperature when the furnace is started from ...

Page 46: ...jects to gain heat at a lower temperature and then reset the controller to a temperature close to the desired maximum or heat using a slowly controlled ramp rate For more information refer to the controller instructions The product s elements are very susceptible to mechanical shock Take great care when loading or unloading the chamber If it is necessary to load or unload work at elevated temperat...

Page 47: ...ctrical measurement Over Temperature Safety Circuit if fitted Set an over temperature setpoint lower than the displayed temperature and check for an over temperature alarm as detailed in this manual Over Temperature Safety Circuit if fitted Electrical measurement Door Plug Visual inspection checking the seal and whether it is free of damage Door Plug Replacement where necessary Chimney Extraction ...

Page 48: ...t incor porating a test of all functions Performance Element Circuit Electrical measurement Power Consumption Measure the current drawn on each phase circuit Hearth Visual check for fit and damage Cooling Fans if fitted Check whether the cooling fans are working 48 ...

Page 49: ...oller set a safe temperature above ambient The heater lights should illuminate l Open the door and check the heater lights They should no longer be illuminated If the heater lights remain illuminated when the door is open discontinue use and contact Carbolite Gero Service Annual check The following checks should be carried out by a qualified electrician as specified in the Maintenance Schedule sec...

Page 50: ...tory and at customers premises throughout the world A telephone call or email often enables a fault to be diagnosed and the necessary parts to be despatched In all correspondence please quote the serial number and model type given on the rating label of the product The serial number and model type are also given on the back of this manual when supplied with the product Carbolite Gero Service and C...

Page 51: ...ng of a new thyristor further adjustment may be required The maximum element currents for this model are listed in section 11 0 Please contact Carbolite Gero for further information 7 8 Low Voltage Compensation If the supply voltage proves to be routinely below the nominal figure for which the furnace has been set up there is a 2 position on the transformer primary side which may be used instead o...

Page 52: ... but much higher levels may be encountered during maintenance or repair Whilst there is no evidence of any long term health hazards it is strongly recommended that safety precautions are taken whenever the materials are handled Exposure to fibre dust may cause respiratory disease When handling the material always use approved respiratory protection equipment RPE eg FFP3 eye protection gloves and l...

Page 53: ...lectrical supply turn the potentiometer on the thyristor fully to the left anti clockwise This sets the output current of the thyristor to off Connect the electrical supply with the side cover off TAKE CARE Set the furnace temperature to maximum Allow the furnace to start heating up Measure the current through the element circuit This is carried out with the clip on meter around one pair of thick ...

Page 54: ...tag is bent back or the screw inserted to grip the sheath 8 8 Element Installation and Replacement See section 8 2 wearing a face mask is required See section 0 1 Safety Warning molybdenum disilicide Molybdenum disilicide elements form a glazed surface when heated Internal stresses can form through heating and cooling which render the glaze fragile The glaze can sometimes splinter into a shower of...

Page 55: ... of the element and a minimum clearance of 15 mm from the sides of the chamber The elements should be parallel with the side walls Replacements Read the section above on initial installation Remove the aluminium braids and clips using the clip tool provided with the furnace Lift out the old elements and the insulation blocks handle the insulation pieces with care as they are fragile Carefully loos...

Page 56: ...airs and Replacements Element Fitting Layout Use of Clip Tool The tool comprises two levers 1 Clip tool 2 Apply hand pressure Key A Braid B Roof Insulation C Element block D Element E Element Clamp See text 56 ...

Page 57: ...required if the electrical supply voltage differs from the present setting To access the transformer tappings first disconnect the furnace from the electrical supply and then remove the left hand side cover see section 8 3 Positions below are given from a viewing position at the left end of the furnace On the left side are the secondary tappings which should not require change but can be checked a...

Page 58: ...rmer primary tapping including the 2 requires adjustment of the thyristor current see section 8 4 The terminal between the link connection is not used 8 11 Fuse Replacement Fuses are accessed by removal of the appropriate panel as described in the Panel Removal section Depending on the model supply fuses and control circuit fuses may be mounted in their own holders or may be on a circuit board tha...

Page 59: ...59 8 0 Repairs and Replacements ...

Page 60: ... low temperature The door switch may be faulty or need adjustment The thyristor fuse may have blown The power thyristor could be failing to switch on due to internal failure faulty wiring from the controller or fault controller There are no lights glowing on the controller Check the supply fuses and any fuses in the product control compartment The controller may be faulty or not receiving a supply...

Page 61: ...ave been moved out of the furnace The thermocouple may be connected the wrong way around The controller may be faulty 2 The HEAT light does not go off with the instrument switch and the fault persists when a 2 A control fuse is removed from its fuse holder The power thyristor has failed ON Check for an accidental wiring fault which could have overloaded the thyristor Isolate the furnace if this fa...

Page 62: ...10 0 Wiring Diagrams 10 0 Wiring Diagrams 10 1 Single Phase 208 V 220 240 V Thermal cutouts case temperature sensor transformer temperature sensor Wire colour BU Blue R Red P Pink G Grey 62 ...

Page 63: ...GR Y Green Yellow 63 10 0 Wiring Diagrams ...

Page 64: ...le below for fuse rating Model Phases Volts Supply Fuse Rating Thyristor Fuse Rating Current Limit element circuit HTF 18 4 1 phase 208 25 A 30 A 140 A HTF 18 4 1 phase 220 240 25 A 30 A 140 A HTF 18 4 2 phase N 380 415 16 A 30 A 140 A 2 phase designs use the line to line voltage neutral is used for the control circuit see section 7 7 the current limit setting at lower temperatures is 146 A 11 2 P...

Page 65: ...Please refer to the rating label for product specific information 65 11 0 Fuses and Power Settings ...

Page 66: ...Maximum power as measured included ancillary components and transformer losses 12 1 Environment The models listed in this manual contains electrical parts and should be stored and used in indoor conditions as follows Temperature 5 C 40 C Relative humidity Maximum 80 up to 31 C decreasing linearly to 50 at 40 C altitude not exceeding 2000 m electrical supply fluctuation not exceeding 10 overvoltage...

Page 67: ...Notes Service Record Engineer Name Date Record of Work ...

Page 68: ... us at the address below or ask your nearest stockist For preventive maintenance repair and calibration of all furnace and oven products please contact Carbolite Gero Service Telephone 44 0 1433 624242 Fax 44 0 1433 624243 Email ServiceUK carbolite gero com Carbolite Gero Ltd Parsons Lane Hope Hope Valley S33 6RB England Telephone 44 0 1433 620011 Fax 44 0 1433 621198 Email Info carbolite gero com...

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