Carbolite HT Guide

www.norrscope.com
Installation, Operation &
Maintenance Instructions
Laboratory & Industrial High Temperature Ovens
and High Temperature Clean Room Ovens
LHT and HT models
This manual is for the guidance of operators of the above Carbolite products
and should be read before the oven is connected to the electricity supply.
CONTENTS
Section page
1.0 Symbols & Warnings 1
2.0 Installation 3
3.0 Operation 5
4.0 Maintenance 7
5.0 Repairs & Replacements 8
6.0 Fault Analysis 10
7.0 Circuit Diagrams 11
8.0 Fuses & Power Settings 13
9.0 Specifications 16
Manuals are supplied separately for the temperature controller
(and overtemperature controller when fitted).
Please read the controller manuals before operating the oven.
1.0
MF16 – 3.04

High Temperature Ovens
SYMBOLS & WARNINGS
1.1 Switches and Lights
Supply Light: when the oven is connected to the electrical supply the light
in the adjacent switch glows
1.2 Warning Symbols
DANGER of electrical shoc
k
– read any warning printed by this sy
m
b
ol.
DANGER – hot surface. Read any warning printed by this symbol.
WARNING: all surfaces of an oven may be hot.
DANGER – read any warning printed by this symbol.
2 MF16

High Temperature Ovens
2.0 INSTALLATION
2.1 Unpacking & Handling
Lift the unit by its base. The door should not be used to support the equipment when moving it.
Use two people to carry the oven where possible. Remove any packing material from the inner
chamber before use.
Lift the unit by its base. Do not use the door or any other projecting cover or component to support
the equipment when moving it. Use two people to carry the oven where possible. Remove any
packing material from the inner chamber before use, and locate the shelves as required.
2.2 Siting & Setting Up
Place the oven on a level surface.
Ensure that there is free space around the oven. Ensure that any vents in the oven are not
obscured.
Ensure that the oven is placed in such a way that it can be quickly switched off or disconnected
from the electrical supply - see below.
MF16 3

High Temperature Ovens
2.3 Electrical Connections
Connection by a qualified electrician is recommended.
All ovens covered by this manual may be ordered for single phase A.C. supply, which may be
Live to Neutral non-reversible, Live to Neutral reversible or Live to Live. Some models may be
ordered for use on a three phase supply with neutral (e.g. 380/220V) or for three phase without
neutral (delta); some for two phases out of a 3-phase + neutral supply.
Check the Oven rating label before connection. The supply voltage should agree with the voltage
on the label, and the supply capacity should be sufficient for the amperage on the label.
The supply should be fused at the next size equal to or higher than the amperage on the label. A
table of the most common fuse ratings is also given in section 8.1 of this manual. Where a supply
cable is present there are internal supply fuses; customer fusing is preferred but not essential.
Oven with supply cable: either wire directly to an isolator or fit with a line plug.
Oven without supply cable: a permanent connection to a fused and isolated supply should be made
to the internal terminals after temporary removal of the Oven back panel.
Connection by line plug: the plug should be within reach of the operator, and should be quickly
removable.
Connection to isolating switch: this should operate on both conductors (single phase) or on all live
conductors (three phase), and should be within reach of the operator.
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)
supply Terminal label Cable colour
2- or 3-phase L1 Black to phase 1
L2 Black to phase 2
L3 Black to phase 3 except 2-phase
N Light Blue to neutral except delta
PE Green/Yellow to earth (ground)
4 MF16

High Temperature Ovens
3.0 OPERATION
The instructions for operating the temperature controller are given in a separate manual.
If the oven is fitted with a time switch, see also the supplementary manual MS03.
If cascade control is fitted, see the supplementary manual MS07.
If the oven has variable speed fan, air extraction or stoving and curing options, please also see the
appropriate section on the next page of this manual.
3.1 Operating Cycle
The oven is fitted with a combined Supply light and Instrument switch. The light is on whenever
the oven is connected to the supply. The switch cuts off power to the controller(s).
The circulation fan operates when the instrument switch is switched on. In the LHT models the
case cooling fans operate when the instrument switch is on.
Connect the oven to the electrical supply. The Supply light should glow .
Operate the instrument switch to activate the temperature controller; the O position is off, the
I position on. The controller becomes illuminated and go through a short test cycle.
Adjust the temperature controller – see the controller manual.
Overtemperature option only. If the overtemperature controller has not yet been set as required,
set it and activate it according to the instructions in the appropriate manual.
Unless a time switch is fitted and is off, the oven begins to heat up according to the controller set
point or program.
To switch the oven off, set the Instrument switch to O. If the oven is to be left off, isolate it from
the electrical supply.
DO NOT switch off if the temperature is above 300°C - damage could be caused to the fan and
motor. Adjust the controller or the overtemperature controller to allow the temperature to fall.
3.2 Overtemperature Control (if fitted)
The overtemperature controller should typically be set at 15°C above the main controller. If an
overtemperature condition occurs, check the possibility that the main control system has failed.
An overtemperature condition cuts off power to the heating elements. It is indicated by a light in
the overtemperature controller flashing. To reset the condition, either allow the oven to cool, or
increase the overtemperature setting, then follow the instructions in the appropriate manual.
3.3 Explosive Vapours
The standard models are not suitable for drying or heat treatment applications where vapours are
released which are combustible or which can form explosive mixtures with air. For such
applications only use models supplied specially for the purpose.
3.4 Atmospheres
When an optional gas inlet is fitted there is a label near the inlet saying "INERT GAS ONLY". In
practice inert or oxidising gases may be used, but not combustible or toxic gases. The oven
chambers are not gas tight, so it should be understood that gas usage may be high, and that the
chamber is likely always to contain some air. Residual oxygen levels of 1% are to be expected.
MF16 5

High Temperature Ovens
3.5 Variable Speed Fan Option
When this is ordered, a variable speed control is fitted in the fan circuit. Operation of the control is
self-explanatory.
Please note that there is a minimum setting at which the fan motor starts up when the oven is
switched on. Find this setting by experiment, and mark the position on the control or front panel.
It is unlikely that a control setting of less than 50% would be required, as there would be very
little air flow around the oven.
3.6 Exhaust Fan Option
Start the extraction unit using the amber switch on the control panel; this is only functional when
the instrument switch is on.
The amount of air exhaust can be controlled by adjusting the slider under the exhaust box.
When the exhaust fan is turned on, there may be a drop in internal temperature before the oven
recovers to the setpoint value.
When working near to the maximum temperature, the airflow should be small to reduce the
amount of energy wasted in heating air.
3.7 Stoving and Curing Option
The oven is fitted with an explosion relief panel and a powered exhaust fan. The exhaust fan is
physically similar to that described above.
With this option the fan runs all the time that the oven is switched on.
A pressure switch detects that there is sufficient air flow through the chamber, and prevents the
oven from heating if the exhaust fan is not working correctly. If the pressure switch does not
detect sufficient air flow, a fault light comes on and the oven is prevented from heating up.
At least 200mm free space must be left at the back and side of the oven to allow the explosion
relief panel to break out if there is a rapid build up of pressure inside the chamber.
6 MF16

High Temperature Ovens
4.0 MAINTENANCE
4.1 General Maintenance
No routine maintenance is required other than the occasional replacement of consumable items.
The oven outer surface may be cleaned with a damp cloth. Do not allow water to enter the interior
of the case. Do not clean with organic solvents.
The fan motor is sealed for life; no lubrication is required.
4.2 Calibration
After prolonged use the controller and/or thermocouple could require recalibration. This would be
important for processes which require accurate temperature readings. A quick check using an
independent thermocouple and temperature indicator should be made from time to time to
determine whether full calibration is required.
For a quick check of the temperature shown by the control thermocouple and oven controller, a
portable temperature indicator and probe thermocouple may be used.
Depending on the controller, the controller manual may contain calibration instructions.
4.3 After Sales Service
Carbolite’s service division (Thermal 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 Thermal 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 a fan and motor
assembly, a thermocouple, a solid state relay, an instrument switch, an element or set of elements,
and a door seal. Individual spares are also available.
When ordering spares please quote the model details as requested above.
4.5 Power Adjustment
The control system incorporates electronic power limiting, but in these models the power limit is
set to 100% and the power limit parameter OP.Hi may be inaccessible to the operator.
Rarely, in the case of uncommon voltages (e.g. outside the range 220-240V or the 3-phase
equivalent), the power limit parameter may be set to a value other than 100%. Do not increase the
value to 100%. See section 8.2 for details of any power limit settings.
Occasionally the power limit is set to zero to permit demonstration of the controls without the
heating elements taking power. In this case the power limit is accessible to the operator and may
be reset to its standard value, usually 100: see section 8.2.
MF16 7

High Temperature Ovens
5.0 REPAIRS & REPLACEMENTS
5.1 Safety Warning – Disconnection from Supply
Always ensure that the oven is disconnected from the supply before repair work is
carried out.
5.2 Safety Warning - Refractory Fibrous Insulation
This oven contains refractory fibres in its thermal insulation. These materials may be
in the form of fibre blanket or felt, vacuum formed board or shapes, mineral wool
slab or loose fill fibre.
Normal use of the oven does not result in any significant level of airborne dust from these
materials, but much higher levels may be encountered during maintenance or repair.
Whilst there is no evidence of any long term health hazards, we strongly recommend that safety
precautions are taken whenever the materials are handled.
Exposure to dust from fibre which has been used at high temperatures may cause
respiratory disease.
When handling fibre always use an approved mask, eye protection, gloves and long
sleeved clothing.
Avoid breaking up waste material. Dispose of waste fibre in sealed containers.
After handling rinse exposed skin with water before washing gently with soap (not
detergent). Wash work clothing separately.
Before commencing any major repairs we recommend reference to the European Ceramic Fibre
Industry Association Bulletin No. 11 and the UK Health and Safety Executive Guidance Note
EH46.
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 Panel Removal
Disconnect the oven from the electrical supply.
Control panel - LHT Models. Open the door and remove two screws located in recesses on the left
side of the control panel (these screws are covered with plastic caps). Lift the panel, pull forward
the bottom of the panel, and lower the panel to disengage it from the top of the body. Note that the
panel remains connected by wiring. Do not disconnect any wiring without first making a careful
note of all the connections.
Control panel - HT models. Remove the screws holding the panel. Note that the panel remains
connected by wiring. Do not disconnect any wiring without first making a careful note of all the
connections.
Internal Element Cover. Open the door. Remove any screws holding the panel and any clips
holding thermocouples in position. Remove the cover.
5.4 Temperature Controller Replacement
200 & 201. These controllers are fitted to the back of the control panel, which can be removed as
given above.
Before handling the controller: wear an anti-static wrist strap or otherwise avoid any possibility
of damage to the unit by static electricity.
Refer to the instructions supplied with the replacement controller.
2132, 2416, 2408 etc. Ease apart the two lugs at the side; grip the instrument and withdraw it from
its sleeve; push in the replacement.
8 MF16

High Temperature Ovens
5.5 Solid-state Relay Replacement
Remove the control panel as given above. Make a note how the wires are connected to the solid
state relay, and disconnect them.
Remove the solid state relay from the aluminium plate.
Replace and reconnect the solid state relay ensuring that the heat-conducting thermal pad is
sandwiched between the relay and the base panel or aluminium plate. Alternatively a thin layer of
white, heat-conducting silicon paste may be applied between the new relay and the plate.
The new solid state relay contains a built-in MOV which protects it from short periods of excess
voltage. If the old relay had a separate disc-shaped "MOV" connected between the high voltage
terminals of the old relay, discard the old MOV.
Replace the removed panel.
5.6 Thermocouple Replacement
Remove the control panel and the internal cover as given above.
Make a note of the thermocouple connections, and how the thermocouple is placed and fixed.
Colour codings are:
negative positive (type K)
white green
Disconnect the thermocouple from its controller terminals or terminal block.
Re-assemble with the new thermocouple observing the colour coding.
5.7 Element Replacement
Remove the control panel and the internal cover as given above. LHT: the element terminals are
low down in the side compartment. HT: the element terminals are accessed from the back.
Disconnect the wires from the element terminals. Remove any starlock washers - these may need
to be cut with wire cutters. Remove any clips holding the element inside the chamber, and
withdraw the element.
Reverse the procedure with the new element.
Run the oven at a low temperature and check that it is controlling properly, to find out whether the
element failure was caused by a fault in the control circuit.
MF16 9

High Temperature Ovens
6.0 FAULT ANALYSIS
A. Oven Does Not Heat Up
1. The SUPPLY light is
OFF ÆNo power from the
supply ÆCheck the fuses in the supply
line
2. The SUPPLY light is
ON ÆThe controller shows a very high temperature
or a code such as S.br
ÆThe thermocouple has broken
or has a wiring fault
ÆThe controller shows a
low temperature ÆThe SSR could be failing to
switch on due to internal
failure, faulty logic wiring
form the controller, or faulty
controller
ÆThere are no lights
glowing on the
controller
ÆThe controller may be faulty or
not receiving a supply due to a
faulty switch or a wiring fault
B. Oven Overheats
1. Oven only heats up
when the instrument
switch is ON
ÆThe controller shows a
very high temperature ÆThe controller is faulty
ÆThe controller shows a
low temperature ÆThe thermocouple may have
been shorted out or may have
been moved out of the oven
ÆThe thermocouple may be
mounted the wrong way round
ÆThe controller may be faulty
2. Oven heats up when
the instrument switch
is OFF
ÆThe SSR has failed
“ON” ÆCheck for an accidental wiring
fault which could have
overloaded the SSR
10 MF16

High Temperature Ovens
7.0 CIRCUIT DIAGRAMS
7.1 Single Phase
coil
Supply ligh
t
Instrument Switch
temperature
controller
PE
L
N
F1
SSR
e
l
e
m
e
n
t
(s)
F2
Filter
(
if fitted
)
thermocou
p
le
circulation
fan
overtemp.
controller thermocou
p
le
relay o
r
contactor
case cooling
fans
(if fitted)
if o’temp
fitted
7.2 Two-phase with Neutral
As 3-phase with neutral (7.4), but with phase L3 not present, and with two SSRs and element
circuits.
7.3 Three Phase with Neutral
Supply ligh
t
Instrument Switch
e
l
e
m
e
n
t
(s)
F1
F2
N
L1
PE
Filter
(
if fitted
)
contacto
r
L2
L3
SSR
SSR
note on 2- or 3-
p
hase: depending on EMC filter, there may be 2 or 3 neutral wires
f
rom the elements to the
f
ilter and terminal blocks
SSR
e
l
e
m
e
n
t
(s)
e
l
e
m
e
n
t
(s)
instrument and fan
circuit as above
MF16 11

High Temperature Ovens
7.4 Three Phase without Neutral (delta e.g. 208-240V)
7.5 Three phase without Neutral (star – e.g. 380-415V)
The circuit is similar to 7.4, but the “neutral” ends of the
elements are not connected to a neutral terminal block.
The control circuit contains an isolating transformer to reduce
the control voltage to 240V or similar.
7.6 Higher Voltages (e.g.254V)
The control circuit contains an isolating transformer to reduce
the control voltage to 240V or similar.
7.7 Stoving & Curing
Supply ligh
t
Instrument Switch
e
l
e
m
e
n
t
(s)
F1
F2
L1
PE
Filter
(
if fitted
)
contacto
r
L2
L3
SSR
SSR
SSR
e
l
e
m
e
n
t
(s)
e
l
e
m
e
n
t
(s)
instrument and fan
circuit as above
F2
transforme
r
F2
Supply light &
Instrument Switch
The following addition is made to the circuit.
Fan Moto
r
exhaust Fan
Fault ligh
t
COIL
Pressure
Switch
o/temp if
fitted
Relay or Contacto
r
element circui
t
control circui
t
12 MF16

High Temperature Ovens
8.0 FUSES & POWER SETTINGS
8.1 Fuses
F1-F2: Refer to the circuit diagrams.
F1 Internal
supply fuses Fitted if supply cable fitted.
Fitted on board to some types of EMC filter. on-board and up to 16 Amps:
32mm x 6mm type F
other: GEC Safeclip
F2 Auxiliary
circuit fuses Fitted on board to some types of EMC filter.
May be omitted up to 25Amp/phase supply
rating.
2 Amps glass type F
On board: 20mm x 5mm
Other: 32mm x 6mm
Customer
fuses Required if no supply cable fitted.
Recommended if cable fitted. See rating label for amperage; see
table below for fuse rating.
Model phases Volts Supply
Fuse rating
LHT4/30 1-phase 220-240 5A
LHT4/60 1-phase 220-240 7A
LHT4/120 1-phase 220-240 10A
LHT5/30 1-phase 220-240 10A
LHT5/60 1-phase 220-240 10A
LHT5/120 1-phase 220-240 12.5A
LHT6/30 1-phase 220-240 10A
LHT6/60 1-phase 220-240 10A
LHT6/120 1-phase 220-240 12.5A
HT4/28 1-phase 220-240 5A
HT4/95 1-phase 220-240 12.5A
HT4/220 1-phase 380/220 - 415/240 12.5A
HT5/28 1-phase 220-240 10A
HT5/95 1-phase 220-240 12.A
HT5/220 1-phase 220-240 20A
HT5/220 2-phase+N 380/220 -415/240 10A
HT6/28 1-phase 220-240 10A
HT6/95 1-phase 220-240 20A
HT6/95 2-phase+N 380/220 -415/240 10A
HT6/220 1-phase 220-240 30-32A
HT6/220 3-phase+N 380/220 - 415/240 15-16A
HT6/220 3-phase delta 220-240 20A
8.2 Power Settings
All models are designed for a power limit (OP.Hi) of 100% with the following exceptions to date:
- any model on 254V or 440V: 89%
MF16 13

High Temperature Ovens
14 MF16

High Temperature Ovens
MF16 15

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)
Approx.
Capacity Net Weight
(°C) (kW) HWD(l) (kg)
Laboratory High Temperature Ovens
LHT4/30 400 1 300 300 310 28 75
LHT4/60 400 1.5 400 400 410 66 100
LHT4/120 400 2.25 650 460 410 128 137
LHT5/30 500 2 300 300 310 28 75
LHT5/60 500 2.5 400 400 410 66 100
LHT5/120 500 3 650 460 410 128 137
LHT6/30 600 2 300 300 310 28 75
LHT6/60 600 2.5 400 400 410 66 100
LHT6/120 600 3 650 460 410 128 137
Industrial High Temperature Ovens
HT4/28 400 1 305 305 305 28 62
HT4/95 400 3 455 455 455 94 144
HT4/220 400 3 610 610 610 227 200
HT5/28 400 2 305 305 305 28 62
HT5/95 500 3 455 455 455 94 144
HT5/220 500 4.5 610 610 610 227 200
HT6/28 600 2 305 305 305 28 62
HT6/95 600 4.5 455 455 455 94 144
HT6/220 600 6 610 610 610 227 200
High Temperature Clean Room Ovens
HT4/28CR to HT6/220CR
The size and power data is the same as for Industrial High Temperature Ovens
9.2 Environment
The ovens 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
MF16-3.04 19/4/01 HT
Carbolite, Parsons Lane, Hope,
Hope Valley, S33 6RB, England.
Telephone: [phone]
Int: [phone]
Facsimile: [phone]
Int: [phone]
E-mail: [e-mail]
For preventive maintenance, repair and calibration of all Furnace
and Oven products, please contact:
Thermal Engineering Services
Telephone: UK: 0845 3308035 Int: [phone]
Fax: UK: 0845 3308036 Int: [phone]
Email: [email protected]
The products covered in this manual are only a small part of the wide range of
ovens, chamber furnaces and tube furnaces 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
y
our nearest stockist.