background image

 

MF47-3.05 

 

4.0

 

M

AINTENANCE

 

4.1

 

Routine Maintenance 

Preventive rather than reactive maintenance is to be preferred. The type and frequency depends on 
furnace use: the following are recommended. 

4.1.1

 

Cleaning 

The furnace outer surface may be cleaned with a damp cloth. Do not allow water to enter the 
interior of the case or chamber. Do not clean with organic solvents. 

4.1.2

 

Safety Switch 

The door switch operation mentioned in 3.2 should be checked periodically to ensure that heating 
elements are isolated when the door is opened. In normal conditions the safety arrangement should 
outlast the furnace, but it could be affected by rough handling, a corrosive environment or work 
materials, or exceptional frequency of use. The frequency of checking depends on furnace use: if in 
doubt, make the check. 

A qualified electrician should check that the supply to the heating elements is cut, with and 
without power being on, when the door is open partially and fully; it is important that isolation is 
not just marginally achieved. The check should be made on the element ends or braids after 
removal of the case top. Note that both live supply wires of a 2-phase supply, and both live and 
neutral of a 1-phase supply, should be isolated when the door is opened. 

4.1.3

 

Other Electrical Components 

Regular visual or electrical checks should be made on the condition of the supply cable, and all 
internal fuses and visible internal cables should be inspected periodically. 

4.1.4

 

Element Glaze 

Depending on use the heating elements may lose their glaze and gain a rough appearance. They 
should be checked from time to time. If the glaze has gone, it may be restored by heating the 
furnace up to 1500°C without load, for 2 hours or so. 

4.2

 

Calibration 

After prolonged use the controller and/or thermocouple could require recalibration; see the 
warning about 1700-1800°C thermocouples in section 3.11. This would be important for processes 
which require accurate temperature readings or which use the furnace close to its maximum 
temperature. A quick check using an independent thermocouple and temperature indicator should 
be made from time to time to determine whether full calibration is required. Carbolite can supply 
these items. 

Depending on the controller, the controller manual may contain calibration instructions. 

4.3

 

After Sales Service 

Carbolite’s service division (Carbolite Engineering Services) has a team of Service Engineers 
capable of repair, calibration and preventive maintenance of furnace and oven products at our 

customers’ premises throughout the world. We also sell spares by mail order. A telephone call or 
fax often enables a fault to be diagnosed and the necessary spare part despatched.  

Each furnace has its own record card at Carbolite. In all correspondence please quote the serial 
number, model type and voltage given on the rating label of the furnace. The serial number and 
model type are also given on the front of this booklet when supplied with a furnace. 

To contact Carbolite Engineering Services or Carbolite see the back page of this manual. 

4.4

 

Recommended Spares Kits 

Carbolite can supply individual spares, or a kit of the items most likely to be required. Ordering a 
kit in advance can save time in the event of a breakdown. Each kit comprises one thermocouple, 
one sheath, one power thyristor, one door insulation piece, and a set of elements, clips and braids. 

Summary of Contents for Carbolite HTF 17

Page 1: ...is connected to the electricity supply Manuals for the furnace controller and overtemperature controller are supplied separately Please read the controller manuals before operating the furnace Contents Section Page 1 0 Introduction 2 2 0 Installation 3 3 0 Operation 5 4 0 Maintenance 8 5 0 Repairs Replacements Adjustments 10 6 0 Fault Analysis 15 7 0 Circuit Diagram 16 8 0 Fuses Power Control 18 9...

Page 2: ...an or by someone with a thorough understanding of electrical components and safety Operating should be done by a person who has read this manual and is aware of and understands the safety issues in using high temperature electrically heated equipment Heat Light the adjacent light glows or flashes to indicate that power is being supplied to the elements DANGER of electrical shock read any warning p...

Page 3: ...free space around the furnace and preferably 1 5m above Do not obstruct any of the vents in the case or leave objects of any kind on the top surface In particular the cooling fans in the case must not be obstructed If the furnace is to be used in a process which could liberate hazardous gases then it should be installed together with a suitable fume extraction system A direct connection to the fur...

Page 4: ...nnecting device for the furnace The supply MUST incorporate an earth ground CONNECTION DETAILS supply type Supply Terminal label Cable colour Live Neutral Reversible or Live Live 1 phase L Brown to live to either power conductor N Blue to neutral to the other power conductor PE Green Yellow to earth ground to earth ground 2 phase L1 Black to phase 1 L2 Black to phase 2 N Light Blue to neutral PE G...

Page 5: ...oling fans are still running if the furnace is above that temperature If the furnace is to be left off unattended and has cooled down isolate it from the electrical supply 3 2 Operator Safety Electrical The furnace incorporates a safety switch which interrupts the heating element circuit when the door is opened This prevents the user touching a live heating element but also prevents the furnace fr...

Page 6: ...gen argon or helium atmospheres to 1600 C Reducing atmospheres are not recommended Sulphur dioxide in normal concentrations is not harmful but chlorine and more so fluorine strongly attack even oxidised elements and should be avoided The furnace is not recommended for burning off carbonaceous materials Other Carbolite furnaces are available for this application When an optional gas inlet is fitted...

Page 7: ...uples low temperatures The thermocouples fitted to these models give very low outputs below about 600 C and do not give accurate readings at low temperatures They may show a negative temperature when the furnace is started from cold The furnaces are designed for operation over 800 C they may be run below this temperature but accurate temperature measurement and stability is not assured 3 13 Therma...

Page 8: ...cked from time to time If the glaze has gone it may be restored by heating the furnace up to 1500 C without load for 2 hours or so 4 2 Calibration After prolonged use the controller and or thermocouple could require recalibration see the warning about 1700 1800 C thermocouples in section 3 11 This would be important for processes which require accurate temperature readings or which use the furnace...

Page 9: ...s case the power limit is accessible to the operator and may be reset to its standard value of 100 4 6 Power Adjustment Thyristor The current limiting thyristor stacks which control power to the elements are fitted with an adjustable resistor which is factory set to limit the maximum current supplied In the event of a change of supply voltage or the fitting of a new thyristor re adjustment is requ...

Page 10: ...ion Wool industry www ecfia eu We can provide further information on request Alternatively our service division can quote for any repairs to be carried out at your premises or ours 5 3 Side Panel Removal Except where explicitly stated always disconnect the electrical supply before removing the side panel Remove the panel by slackening the four fixing screws behind plastic caps at the left hand end...

Page 11: ...back panel 1700 models or top cover 1800 models Make a note of the thermocouple connections The negative leg of the thermocouple is marked blue The compensating cable for 1700 1800 C thermocouples is plain copper Disconnect the thermocouple from its terminal block Undo the screw to release the thermocouple sheath withdraw the sheath and shake out any fragments of thermocouple Re assemble with a ne...

Page 12: ...n 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 loosed and remove the clamps Prepare and install the new elements as explained above Heat up the furnace to a moderate temperature and ensure that the furnace is c...

Page 13: ...MF47 3 05 13 Element Connections 4 Elements Element Connections 5 Elements Terminal Block Element Braid Terminal Block Element Braid ...

Page 14: ...lternatively be L1 and L2 for a live to live supply The L side should be connected to the correct tapping to match the supply voltage The link wire should be in position as shown unless the supply voltage is always low in which case there is the option of moving one end to the 2 terminal Important Changing the transformer primary tapping including the 2 requires adjustment of the thyristor current...

Page 15: ...as activated There are no lights glowing on the controller Check the supply fuses and any fuses in the furnace control compartment The controller may be faulty or not receiving a supply due to a faulty switch or a wiring fault B Furnace Overheats 1 The HEAT light goes OFF with the instrument switch The controller shows a very high temperature The controller is faulty The controller shows a low tem...

Page 16: ...pply fuses present if supply cable fitted F2 Auxiliary circuit fuses 2A F4 Thyristor protection fuse Ferraz Protistor BU Blue R Red P Pink G Grey GR Y Green Yellow Coil N Elements Contactor BU R Thyr istor BU R OTC P G TC Control thermocouple O temp thermocouple Door Switch Element Transformer Heat Light Case Cooling Fans F2 F1 GR Y PE L EMC Filter F4 Thermal Cutouts Fault Light Instrument Switch ...

Page 17: ...f supply cable fitted F2 Auxiliary circuit fuses 2A F4 Thyristor protection fuse Ferraz Protistor BL Black BU Blue P Pink G Grey GR Y Green Yellow Coil L2 Elements Contactor BU BL Thyr istor BL BU OTC P G TC Control thermocouple O temp thermocouple Door Switch Element Transformer Case Cooling Fans F2 F1 GR Y PE L1 EMC Filters F4 Thermal Cutouts N F1 Fault Light BL 94KΩ Heat Light Instrument Switch...

Page 18: ...ld be 100 for all models The current limiting thyristor stacks are set to the maximum element currents given in the table TABLE OF FUSE AND CURRENT LIMIT VALUES Model Phases volts supply fuse rating thyristor fuse rating current limit element circuit HTF 17 5 1 phase 208 20A 30A 150A HTF 17 5 1 phase 220 240 20A 30A 150A HTF 17 10 1 phase 208 30A or 32A 50A 150A HTF 17 10 1 phase 220 240 30A or 32...

Page 19: ... 5 106 HTF 18 4 1800 C 4 6 141 140 205 4 2 92 HTF 18 8 1800 C 6 2 210 190 205 8 2 4 113 Maximum power as measured included ancillary components and transformer losses 9 2 Environment The furnaces contain 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...

Page 20: ...es manufactured by Carbolite for laboratory and industrial use For further details of our standard or custom built products please contact us at the address below or ask your nearest stockist Copyright 2014 Carbolite Limited For preventive maintenance repair and calibration of all Furnace and Oven products please contact Carbolite Engineering Services Telephone 44 0 1433 624242 Fax 44 0 1433 62424...

Reviews: