Installation, Operation & Maintenance Instructions 1400°C - 1600°C Chamber Furnaces RHF models: 3 litre - 35 litre This manual is for the guidance of operators of the above Carbolite products and should be read before the furnace is connected to the electricity supply. CONTENTS Section 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.
RHF 1.0 SYMBOLS & WARNINGS 1.1 Switches and Lights Instrument switch: when the instrument switch is operated the temperature control circuit is energised. Heat Light: the adjacent light glows or flashes to indicate that power is being supplied to the elements 1.2 Warning Symbols DANGER of electrical shock– read any warning printed by this symbol. DANGER – hot surface. Read any warning printed by this symbol. WARNING: all surfaces of a furnace may be hot.
RHF connection to the furnace chimney as this causes excessive airflow through the chamber and results in poor temperature uniformity. 2.3 Heating Elements The Silicon Carbide elements are VERY FRAGILE and are packed separately. Fit them according to the instructions in section 5.7. 2.4 Electrical Connections Connection by a qualified electrician is recommended. Models RHF 14/3, 15/3, 16/3 and 14/8 may be ordered for single phase use or for two phases out of a three phase supply with neutral.
RHF 3.0 OPERATION The instructions for operating the temperature controller are given in a separate manual. If the furnace is fitted with a time switch, see also the supplementary manual MS03. If cascade control is fitted, see the supplementary manual MS07. 3.1 Operating Cycle The furnace is fitted with an instrument switch. The switch cuts off power to the control circuit. Connect the furnace to the electrical supply. Operate the instrument switch to activate the temperature controller.
RHF 3.3 Use of Probes Any metal object used to probe into the furnace chamber while the furnace is connected to the supply must be earthed (grounded). This applies in particular to metal sheathed thermocouples, where the sheaths must be earthed. The refractory material of the chamber lining becomes partly conducting at high temperatures, and the electric potential inside the chamber can be at any value between zero and the supply voltage. Unearthed probes can cause serious electric shock. 3.
RHF 4.0 MAINTENANCE 4.1 General 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 Soot deposits may form inside the furnace, depending on the process. At appropriate intervals remove these by heating as indicated in section 3.2. 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.
RHF 4.5 Element Ageing Silicon carbide elements gradually increase in resistance with use: a process known as ageing. Their heating power reduces correspondingly. To ensure sufficient power to the furnace it may be necessary to adjust the power limit, and, ultimately, to replace the elements - taking care to readjust the power limit. If the furnace does not reach temperature, or is slow, measure the element resistances and calculate the required power limit using the method given above.
RHF 5.0 REPAIRS & REPLACEMENTS 5.1 Safety Warning – Disconnection from Supply Always ensure that the furnace is disconnected from the supply before repair work is carried out. 5.2 Safety Note - Refractory Fibrous Insulation Insulation made from High Temperature Insulation Wool Refractory Ceramic Fibre, (better described as Alumino Silicate Wool) (ASW) This product contains alumino silicate wool products in its thermal insulation.
RHF 5.5 Fuse Replacement Fuses are marked on the circuit diagram (section 7.0) with type codes, e.g. F1, F2. A list of the correct fuses is given in section 8.1. Depending on model and voltage, the different fuse types may or may not be fitted. If any fuse has failed, it is advisable for an electrician to check the internal circuits. Replace any failed fuses with the correct type. For safety reasons do not fit larger capacity fuses without first consulting Carbolite.
RHF 10 MF07 – 3.
RHF 6.0 FAULT ANALYSIS A. Furnace Does Not Heat Up 1. The HEAT light The heating element has failed is ON 2. The HEAT light is OFF Check also that the SSR is working correctly The controller shows a very high temperature or a code such as S.
RHF 7.0 CIRCUIT DIAGRAMS In all RHF models the safety switch in the diagram is a positive-break door switch. EMC Filters (if fitted): dependent on the model there may be one filter, or more than one fitted in parallel. The circuit diagram examples do not show multiple filter arrangements. 7.1 Single Phase Filter (if fitted) N F1 F3 L contactor F2 PE e l e heat m on e n t (s) F3 Instrument Switch safety switch overtemp. controller temperature controller 7.
RHF 7.4 3-phase without neutral (delta – 208 to 240V) L3 L2 L1 Filter (if fitted) F1 contactor F2 PE F3 safety switch overtemp. controller coil if fitted F3 e l e heat m on e n t (s) e l e heat m on e n t (s) F3 SSR thermocouple F3 temperature controller SSR F3 thermocouple 7.5 F3 e l e heat m on e n t (s) Instrument Switch SSR 3-phase without neutral (star – e.g.
RHF 8.0 FUSES & POWER SETTINGS 8.1 Fuses F1-F3: Refer to the circuit diagrams. F1 Internal supply fuses Fitted if supply cable fitted. Fitted on-board to some types of EMC filter. F2 Auxiliary circuit fuses Fitted on-board to some types of EMC filter. May be omitted up to 10 Amp/phase supply rating. F3 Heat Light fuses Customer fuses May be omitted up to 25 Amp/phase supply rating. Required if no supply cable fitted. Recommended if cable fitted.
RHF 8.2 Power Settings The power limit settings (parameter OP.Hi) for the RHF models on various supply voltages are as follows. The figures represent the maximum percentage of time that controlled power is supplied to the elements. Do not attempt to “improve performance” by setting a value higher than the correct one from the table.
9.0 SPECIFICATIONS Carbolite reserves the right to change specifications without notice. 9.1 Models Covered by this Manual MODEL Max. Temp. Max. Power Chamber Size (mm) (°C) (kW) H W Chamber Furnaces heated by Silicon Carbide elements. RHF 14/3 1400°C 4.5 120 120 RHF 14/8 1400°C 8.0 170 170 RHF 14/15 1400°C 10.0 220 220 RHF 14/35 1400°C 16.0 250 300 RHF 15/3 1500°C 4.5 120 120 RHF 15/8 1500°C 8.0 170 170 RHF 15/15 1500°C 10.0 220 220 RHF 15/35 1500°C 16.0 250 300 RHF 16/3 1600°C 4.
