Carbolite ELF Series Guide

Installation, Operation &
Maintenance Instructions
1100°C Chamber Furnaces
ELF models
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 page
1.0 Introduction 1
2.0 Installation 2
3.0 Operation 5
4.0 Controller Operation 7
5.0 Overtemperature Control Option 13
6.0 Maintenance 14
7.0 Repairs & Replacements 14
8.0 Fault Analysis 19
9.0 Circuit Diagram 20
10.0 Specifications 21
This manual should supply all the information required for safe and trouble-
free furnace operation. Information on controller operation is included.
1.0
MF01 – 3.20

ELF (B)
INTRODUCTION
1.1 Models Covered by this Manual
This manual covers the Carbolite furnace models ELF 11/6B and ELF 11/14B. The B suffix
indicates differences from earlier models, in particular that the heating element is enclosed in an
inner metal chamber, and the heating wires are partly exposed in the chamber sides and radiate
freely into the chamber. The B models were not made before mid-2001.
The B versions also allow for a simple customer adjustment to increase the air flow through the
chamber. Carbolite do not claim that this adjustment makes the furnace suitable for ashing or
burn-off applications.
The B versions may be set to operate on any single-phase voltage in the range 200-240V (or 100-
120V to order) by correct setting of the power limit parameter in the controller.
Because of model changes it is very important when ordering spares to state the furnace serial
number or otherwise to identify the model correctly.
1.2 Switches and Lights
Supply Light: when the furnace is connected to the electrical supply the
light in the adjacent switch glows
Heat Light: the adjacent light glows or flashes to indicate that power is
being supplied to the elements
1.3 Warning Symbols
DANGER of electrical shoc
k
– 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.
DANGER – read any warning printed by this symbol.
2.0
2 MF01

ELF (B)
INSTALLATION
2.1 Unpacking & Handling
When unpacking or handling the furnace always lift it by its base. Never lift it by the door. Use
two people to unpack and carry the furnace.
Carefully remove any packing material from the furnace chamber. Avoid damaging the
surrounding insulation when removing packing materials.
2.2 Siting & Setting Up
Place the furnace in a well ventilated room, away from other sources of heat, and on a non-
inflammable surface that is resistant to accidental spillage of hot materials.
Ensure that there is free space of at least 50mm around the furnace. Do not obstruct any of the
case vents: they are needed to keep the controls and the case exterior cool.
Ensure that the furnace is placed in such a way that it can be quickly switched off or disconnected
from the electrical supply.
2.3 Chimney
The chimney is a short length of ceramic tubing. If it is supplied unfitted, then fit it through the
hole in the top of the furnace case.
If the furnace is to be used to heat substances that emit fumes, then a fume extraction duct of about
150mm inlet diameter may be placed directly above the chimney outlet. Do not attempt make a
sealed connection to the furnace chimney as this causes excessive airflow through the chamber
and results in poor temperature uniformity.
2.4 Hearth
The chamber floor (hearth) is supplied with a ceramic tile. This may already be in position in the
chamber. If it is packed separately, unwrap it and place it carefully on the chamber floor.
2.5 Door Vents
There is a plate fixed to the inner door panel (door plug carrier), accessible by removing the door
insulation piece. This can be positioned to open up holes in the inner door, to allow an increased
air flow in the chamber. Decide on the required position and fix the plate accordingly (see section
7.8).
2.6
MF01 3

ELF (B)
Electrical Connections
Connection by a qualified electrician is recommended.
The furnace requires a single-phase A.C. supply with earth (ground), which may be Live to
Neutral non-reversible (polarised), Live to Neutral reversible (non-polarised), or Live to Live.
Check the following before connection, by reference to the furnace rating label.
Voltage range: the voltage on the label and the actual supply voltage should be in the same range
– either the range 200-240V or the range 100-120V. The furnace must not be connected to the
wrong range. If the voltage is different but in the same range, see section 2.7.
Amps: the actual supply must be capable of supplying the required amps. It should be fused at the
next available fuse size equal to or greater than the amps on the rating label.
A supply cable is fitted to 200-240V models, but may not be to 110-120V models. In there is no
cable, remove the back panel and connect a suitably rated cable to the internal terminals.
Either wire the supply cable directly to an isolator or fit it with a line plug. The plug or isolator
should be within easy reach of the operator to permit quick disconnection of the power.
For operator safety 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)
2.7 Voltage Level
Check the furnace rating label voltage. If the actual supply is not the same as the voltage on the
label, then the controller power limit should be adjusted.
If the actual voltage is higher than the label voltage, then read section 4.15 before switching on.
Either switch on and immediately reduce the setpoint to zero to prevent heating, or follow the
instructions in section 4.15 as quickly as possible. Heating with too high a power limit can burn
out the heating elements or blow a fuse.
If the actual voltage is lower than the label voltage, then the furnace is safe but underpowered. To
regain full power, adjust the power limit as explained in section 4.15.
3.0
4 MF01

ELF (B)
OPERATION
3.1 Operating Cycle
The furnace is fitted with a combined Supply light and Instrument switch. The light is on
whenever the furnace is connected to the supply. The switch cuts off power to the controller.
Connect the furnace to the electrical supply. The Supply light should glow.
Operate the instrument switch, located on the front panel, to activate the temperature controller;
the Oposition is off, the Iposition on. The controller becomes illuminated and goes through a
short test cycle.
Close the furnace door and adjust the temperature controller – see section 4.0.
As the furnace heats up the Heat light glows steadily at first and then flashes as the furnace
approaches the desired temperature. For further information on temperature control see section
4.0.
To switch off, set the instrument switch to O. If the furnace is to be left off, isolate it from the
electrical supply.
3.2 General Operating Notes
Heating element life is shortened by use at temperatures close to maximum. Do not leave the
furnace at high temperature when not required. The maximum temperature for ELF models is
1100°C (2012°2F).
When heating large objects, in particular poor conductors, avoid shielding the thermocouple from
the heating elements. The thermocouple is intended to sense the temperature near the heating
element, but if a large cold object is placed in the chamber it may record the average temperature
of the object and the element, which can lead to overheating of the element. Allow large objects to
gain heat at a lower temperature and then adjust the controller setpoint to a temperature close to
the desired maximum.
Materials such as case hardening compounds and other reactive salts may attack the wire
elements, causing premature failure. The insulation chamber includes a ceramic hearth that helps
to protect the insulated floor.
Note that if the door vents are open then the entry of cold air through the vents can give rise to a
cool area in the chamber.
The moulded light weight ceramic fibre insulation can easily be marked by accidental contact with
tongs etc.. Some fine cracks may be visible at the front of the insulation, or may develop in the
surface of the chamber due to the progressive shrinkage of the ceramic fibres. Cracks are not
usually detrimental to the functioning of the furnace.
When heating materials that produce smoke or fumes, the chimney must be correctly fitted and
unobstructed. Otherwise, soot may accumulate in the chamber and could possibly cause an
electrical breakdown of the heating element. To prevent this, regularly heat the furnace up to
maximum temperature for one hour without load to burn away the soot.
3.3 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. Chamber
furnaces 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.
3.4 Operator Safety
The furnace incorporates a pair of switches that safely interrupt the heating element circuit when
the door is opened. This prevents the user touching a live heating element, but also prevents the
furnace from heating up if the door is left open.
MF01 5

ELF (B)
4.0
6 MF01

ELF (B)
CONTROLLER OPERATION
The controller normally fitted to this furnace is the Carbolite 201 made by Eurotherm.
If any other controller is fitted, then a separate manual is supplied.
If a time switch is fitted, then a separate manual is supplied.
4.1 201 – Basic Features
N
ote: on the 201 display the letters
mand wlook like nand u. In these
instructions the letters are described
as m and w.
When switched on, the controller lights up, goes through a short test routine, and then displays the
measured temperature and starts to control. The output light glows or flashes as heating occurs.
The Page key allows access to parameter lists within the controller; most lists and parameters
are hidden and cannot be accessed by the operator because they contain factory-set parameters
that should not be changed.
A single press of the page key displays the temperature units, normally set to °C; further presses
reveal the lists indicated in the Navigation Diagram in section 4.6.
The Scroll key 4allows access to the parameters within a list. Some parameters are display-only;
others may be altered by the operator. Some parameters only appear in appropriate circumstances
– for example, working setpoint does not appear if setpoint ramp rate is Off.
A single press of the scroll key 4displays the temperature units; further presses reveal the
parameters in the current list indicated in the Navigation Diagram.
To return to the Home list at any time, press Page and Scroll 4together, or wait for 45 seconds.
The Down Tand Up Skeys are used to alter the setpoint or other parameter values.
4.2 Basic Operation
Normally no operator action is required other than entering the setpoint, as the 201 starts to
control on being switched on, as described above.
4.3 Altering the Setpoint
With the display at “home”, showing the measured temperature, press Down Tor Up Sonce to
display the setpoint; press again or hold down to adjust it. The display returns to the measured
temperature when no key is pressed for 0.5 seconds.
4.4 Stopping and Starting Control
It is possible to stop and start the controller without altering the setpoint. Press Scroll 4until the
legend m-A (manual/auto) appears. In the 201, manual means “off” and auto means “on”. Press
Down Tor Up Sonce to show the current on/off state: mAn for off, and Auto for on. Press Tor
Sto change between manual and auto (off and on) as required.
Note that timer modes 1 & 3 set the controller to mAn at the end of the timing period. If the
controller unexpectedly does not control it may be in manual mode, possibly as the result of
previous use of the timer function.
4.5 Altering the Ramp Rate
MF01 7

ELF (B)
It is possible to limit the rate of heating by setting a ramp rate. Press Scroll 4until the legend SPrr
(SetPoint ramp rate) is displayed. Use Down Tor Up Sto display and adjust the value.
The ramp rate sets the maximum rate of heating or cooling in degrees per minute. A value of OFF
cancels the ramp rate, allowing heating and cooling at the maximum rate. When this feature is in
use, there is a “working setpoint” that can be viewed at any time by scrolling to w.SP and pressing
Tor S.
Fig 1 and fig 2 indicate the possible difference between running without and with a ramp-to-
setpoint value (depending on the load and the value used).
4.6 Navigation Diagram
OP.Hi
SPrr
m-A
w.SP
Home
List Input List Output List Access List
20.0 iP oP ACCS
OP
OFS.H
CAL.P
CAL
Pnt.L
OFS.L
Pnt.H
codE
tmr
dwel
StAt
4
tm.OP

4*C
timer status
run or O
F
F
dwell time for
time
r
time remainin
g
timer mode user 2-point
calibration
444
*C
s
etpoint ramp rate
OFF or value
p
ower limit
setting, if
p
resen
t
 
output power,
read only
measured temperature;
use
T / S to access
setpoint
manual/Auto
mAn=off, Auto-on
f
or factory access to
lists and parameters
not available to the
operator
p
resent only if
SPrr in use
enter
p
assword
if user
calibration
8 MF01

ELF (B)
4.7 Operation With the Timer
The 201 can be used as a process timer allowing timed heating or timed delay, according to the
options in the table. There are 5 timer modes, but 2 of them are affected by whether the setpoint
ramp rate feature is being used, making 7 entries in the table. The table also shows the status of
the Timer Light on the 201. A visual impression of the different modes is given in fig 3.
timer mode description timer light
mode 1
Timed dwell and
switch off
The timer starts timing when the actual
temperature is within 1°C of the setpoint.
At the end of the timing period, control
switches off (i.e. goes into Manual) to
allow cooling, and EnD flashes on the
display.
On while temperature is
reaching setpoint.
On during the timing period.
Off from the end of the
timing period.
mode 2
Timed dwell and
stay on
The timer starts timing when the actual
temperature is within 1°C of the setpoint.
At the end of the timing period, control
remains on, maintaining the setpoint
temperature, and End flashes on the
display.
On while temperature is
reaching setpoint.
On during the timing period.
Off from the end of the
timing period.
mode 3, with SPrr off
Time from cold and
switch off
The timer starts timing immediately.
At the end of the timing period, control
switches off (i.e. goes into Manual) to
allow cooling, and End flashes on the
display.
On during the timing period.
Off from the end of the
timing period.
mode 3, with SPrr
active
Dwell from working
setpoint and switch
off
The timer starts timing when the working
setpoint is within 1°C of the setpoint.
At the end of the timing period, control
switches off (i.e. goes into Manual) to
allow cooling, and End flashes on the
display.
On during the timing period.
Off from the end of the
timing period.
mode 4, with Sprr off
Time from cold and
stay on
The timer starts timing immediately.
At the end of the timing period, control
remains on, maintaining the setpoint
temperature, and End flashes on the
display.
On during the timing period.
Off from the end of the
timing period.
mode 4, with Sprr
active
Dwell from working
setpoint and stay on
The timer starts timing when the working
setpoint is within 1°C of the setpoint.
At the end of the timing period, control
remains on, maintaining the setpoint
temperature, and End flashes on the
display.
On during the timing period.
Off from the end of the
timing period.
mode 5
Delayed switch on The timer starts timing immediately, and
control starts at the end of the timing
period.
There is no “END” condition in this mode.
On during the timing period.
Off from the end of the
timing period.
4.8
MF01 9

ELF (B)
Setting the Timer Mode
Scroll to tm.OP; use Tor Sto view and alter the mode. The mode shows as OPt.1 to OPt.5.
It is not possible to alter the mode while the timer is running; if the mode cannot be altered, scroll
to the StAt parameter and set its value to OFF.
4.9 Setting the Time Period
Method 1
Scroll to
tmr (time remaining). Use Tor Sto view the remaining time; the units are always in
minutes. Use Tand Sto set or alter the time. Setting tmr automatically activates the timer; the
m-A parameter changes to Auto and the StAt parameter changes to run.
Note that the tmr display shows 0(zero) during the last minute of timing, and also shows 0when
the time has expired. The timer light indicates whether timing is still in progress.
Method 2
Scroll to
dwEl, and useTand Sto set the timing duration. The advantage of method 2 is that dwEl
need only be set once if repeated use of the same time period is required.
Scroll to
StAt, and use Tor Sto set the parameter value to run. This copies the dwell time into
tmr and activates the timer as in method 1.
4.10 Running with the Timer
Once the timer is activated by method 1 or 2 above, the control sequence depends on the timer
ode, as previously given in the table. Fig 3 gives another representation of the timer action.
4.11
10 MF01

ELF (B)
Stopping the Timer
To stop the timer at any time while it is running, change the StAt parameter to OFF. This is the
same as reducing tmr to zero. The controller then acts as though at has reached the end of the time
period.
4.12 End of Time Period
Modes 1 and 3: heating stops at the end of timing; the m-A parameter changes to mAn.
Modes 2 and 4: heating continues at the end of timing; the m-A parameter remains at Auto.
Mode 5: heating starts at the end of the timing period; the m-A parameter remains at Auto.
In modes 1 to 4 the alarm message EnD flashes on the display at the end of timing; the StAt
parameter remains at run.
In mode 5 there is no End message; the StAt parameter changes to OFF at the end of timing.
4.13 Cancelling the Alarm
To acknowledge (cancel) the EnD alarm, press Page and Scroll together; the StAt parameter
changes to OFF.
Alternatively the alarm may be cancelled by directly changing the StAt parameter from run to OFF.
4.14 User Calibration
The controller is calibrated for life at manufacture against known reference sources, but there may
be sensor errors or other system errors. User calibration allows compensation for such errors, and
the 2132 allows for a user 2-point calibration. This setting is password protected to avoid
accidental alteration.
Page to
iP, scroll to CAL.P, and use Up Sto alter the password. The password is 3. If the correct
password is entered, the display shows PASS. Scroll to CAL and use Tor Sto observe the setting
FACt (factory values, as manufactured) or USEr (user values). Change to USEr.
NOTE: before checking the calibration of the controller, or of the complete system, remember to
reset the 2132 to factory calibration values by setting the CAL.P parameter to FACt.
To enter a user calibration, scroll to each or the following parameters in turn and set the desired
values.
Pnt.L low temperature for which an offset is to be entered
OFS.L offset value for the low temperature
Pnt.H high temperature for which an offset is to be entered
OFS.H offset value for the high temperature
Example: the controller reads 3°C low at 400°C, and 5°C low at 1000°C. The parameter values
should be Pnt.L=400, OFS.L=3, Pnt.H=1000, OFS.H=5.
Negative or positive values can be entered: if the
controller is reading high, negative offsets would
be appropriate.
Fig 4 gives a graphical representation of the 2-
point calibration.
MF01 11

ELF (B)
4.15 Power Adjustment
The furnace control system incorporates electronic power control, including a “power limit”
parameter that is used to reduce the effective voltage to 208V (or 104V); the values of the power
limit OP.Hi parameter for different voltages are as follows:
voltage: 100
200
208 110
220 115 230 120 240
ELF 11/6B &
ELF 11/14B OP.Hi: 100% 100% 89% 81% 75%
To alter the power limit
If the actual supply voltage is higher than the voltage on the rating label or the voltage for which
the furnace was last set, then please perform the following operations quickly and immediately
after switch-on. (Alternatively, temporarily reduce the temperature setpoint to zero to prevent
heating.)
Press Page until oP (output list) is displayed. Press Scroll 4until OP.Hi (Output High) is
displayed. Press Down Tor Up Sonce to display the value of OP.Hi (it is good practice to write
down the original value).
To alter the parameter to the desired value use Down Tor Up S.
Caution: Do not increase the power limit value to a value above the correct level for the supply
voltage. The heating elements could burn out, or a fuse could blow.
Note that setting the power limit to zero prevents the furnace from heating.
4.16 Control at Low Temperatures
If the furnace is to be used at temperatures much lower than its design maximum, control stability
may be improved by reducing the power limit.
Example: It is desired to run the furnace at 300°C. The normal control settings can be expected to
cause excessive overshoot as the furnace reaches temperature. Try a setting of 40%, which should
greatly reduce this overshoot. Experiment may be required to achieve a good result; avoid power
limits below about 30%, as control accuracy falls off at such levels. Note that setting the value to
zero prevents the furnace from heating.
5.0
12 MF01

ELF (B)
OVERTEMPERATURE CONTROL OPTION
This is only fitted when the overtemperature option is ordered. To identify whether it is fitted,
observe the controller panel: if it is fitted the overtemperature key and warning light are present.
The overtemperature key must be held depressed continuously while viewing or adjusting the
overtemperature controller. If the Overtemperature key is released, the display reverts to the main
controller.
N
ote: on the 201 display the letters
mand wlook like nand u. In these
instructions the letters are described
as m and w.
With the key pressed the overtemperature setpoint is normally displayed. To alter the value, use
Down and Up. To view the measured temperature, press Scroll until PV (process variable) is
displayed, then press Down or Up. Keep the overtemperature key depressed during these
operations.
When an overtemperature condition is reached, the overtemperature warning light changes from
green to flashing red. To “accept” or “reset” this alarm condition, press the Overtemperature key
and the Page key together; the warning light changes to continuous red. Once the overtemperature
condition is cleared (by the temperature falling), the light changes to green and normal operation
resumes.
6.0
MF01 13

ELF (B)
MAINTENANCE
6.1 General Maintenance
No routine maintenance is required other than removal of soot deposits mentioned in 3.2 and the
occasional replacement of consumable items.
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.
6.2 Calibration
After prolonged use the controller and/or thermocouple could require recalibration. This would be
important for processes that require accurate temperature readings or that 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.
See also the instructions for calibrating the controller, section 4.14.
6.3 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.
6.4 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 and sheath, one solid state relay, one door insulation piece,
and one complete heating chamber.
When ordering spares please quote the model details as requested above.
7.0
14 MF01

ELF (B)
REPAIRS & REPLACEMENTS
7.1 Safety Warning – Disconnection from Supply
Always ensure that the furnace is disconnected from the supply before repair work
is carried out.
7.2 Safety Warning - Refractory Fibrous Insulation
This furnace 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 furnace 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 that 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.
7.3 Temperature Controller Replacement
The 201 controller is fitted inside the furnace base, which can be separated from the top by
removal of six screws.
Before handling the controller: wear an anti-static wrist strap or otherwise avoid any possibility
of damage to the unit by static electricity.
See the instructions supplied with the replacement controller.
7.4 Solid-state Relay Replacement
Disconnect the furnace from the supply and remove the furnace back panel.
Make a note of the wire connections to the solid state relay, and disconnect them.
Remove the solid state relay from the base panel.
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 base panel or
aluminium plate.
Replace the removed panel.
7.5
MF01 15

ELF (B)
Thermocouple Replacement
Disconnect the furnace from the supply, and remove the furnace back panel.
Make a note of the thermocouple connections. The negative leg of the thermocouple is marked
blue. Compensating cable colour codings are:
negative: white
positive (type K): green
Disconnect the thermocouple from its terminal block and withdraw the thermocouple from its
sheath. It is advisable also to remove the sheath and shake out any broken pieces of thermocouple.
Fit the replacement thermocouple and reconnect, observing the colour coding.
Refit the back panel.
7.6 Element Replacement
See section 7.2 - wearing a face mask is recommended.
The element is supplied in the form of a complete inner chamber.
Disconnect the furnace from the supply and remove the furnace case back panel. Pull the chimney
out of the top of the furnace.
Make a note of the wiring connections (see also thermocouple colours, section 7.5.)
Disconnect the element power leads and the thermocouple connections. Remove the thermocouple
and support tube.
Using a socket spanner undo the four bolts that fasten the insulation box. These are located under
the insulation box in the two cross supports.
Remove the insulation box by carefully sliding it out through the back of the furnace case.
Take the new insulation box and carefully slide it into the back of the furnace up to the front face.
DO NOT support the insulation box by putting your hand inside it – the insulation is fragile.
Locate the insulation box fixing holes and replace the four bolts.
Refit the chimney, thermocouple support tube and thermocouple.
Remake all the thermocouple and element connections according to the notes made. If in doubt,
see the diagram below: on the 200-240V models there are two heating coils in series; on the 100-
120V models two in parallel.
Refit the back panel and run the furnace for 30 minutes at 800°C without interruption to ensure
complete burn-off of any organic binders. Smoke may be observed during this process, so it
should be carried out in a well-ventilated area.
Check that the furnace is controlling properly to rule out the possibility that previous element
failed because of a fault elsewhere in the control circuit.
Example Connections L
L
N
100-120V200-240V
= elemen
t
N
7.7
16 MF01

ELF (B)
Door Plug Replacement
The “door plug” is also known as the “door insulation piece”.
Lower the furnace door to the fully open position.
Loosen the four M6 Screws, two on either side of the door plug carrier.
Remove the door plug and carrier
Remove the air inlet blanking plate screws (section 7.8).
Slide the door plug upwards out of the carrier.
Slide the new door plug into the carrier ensuring that the air inlet holes are aligned, and re-
assemble in the reverse order.
DOOR
DOOR PLUG
CARRIER
DOOR
PLUG
7.8 Air Inlet Adjustment
The air inlet is on the inner door panel (door plug carrier), and is supplied in the closed position. It
can be altered to the open position as follows.
Remove the door plug and carrier as described in section 7.7.
Remove the three screws holding the blanking plate into position and remove the blanking plate.
Position the blanking plate in the upper position clear of the air inlet holes and align the screw
holes.
Replace the three screws to hold the blanking plate in new position. Note that the screws must be
replaced to fix the door plug into position.
BLANKING PLATE
AIR INLET OPEN
POSITION
MF01 17

ELF (B)
7.9 Fuse Replacement
Fuses are marked on the circuit diagram (section 9.1) with type codes, e.g. F1, F2. A list of the
correct fuses is given in section 9.3. Fuses F2 may not be fitted on this furnace.
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.
The fuses are near the cable entry point, and access is by removal of the back panel.
In most models the fuses are mounted on an EMC filter circuit board. If there are 4 fuses, then the
smaller pair is for the control circuit only.
8.0
18 MF01

ELF (B)
FAULT ANALYSIS
A. Furnace Does Not Heat Up
1. The HEAT light
is ON ÆThe heating
element has failed ÆCheck also that the SSR is working
correctly
2. The HEAT light
is OFF The controller
shows a very high
temperature or a
code such as S.br
ÆThe thermocouple has broken or has a
wiring fault
The controller
shows a low
temperature
ÆThe door switch(es) (if fitted) may be
faulty or need adjustment
ÆThe contactor (if fitted) may be faulty
ÆThe SSR could be failing to switch on due
to internal failure, faulty logic wiring from
the controller, or faulty controller
There are no
lights glowing
on the
controller
ÆThe SUPPLY
light is ON ÆThe controller may be
faulty or not receiving a
supply due to a faulty
switch or a wiring fault
ÆThe SUPPLY
light is OFF ÆCheck the supply fuses and
any fuses in the furnace
control compartment
B. Furnace Overheats
1. The HEAT light
goes OFF with
the instrument
switch
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
heating chamber
ÆThe thermocouple may be mounted the
wrong way round
ÆThe controller may be faulty
2. The HEAT light
does not go off
with the
instrument
switch
ÆThe SSR has failed
“ON” ÆCheck for an accidental wiring fault that
could have overloaded the SSR
9.0
MF01 19

www.norrscope.com
ELF (B)
CIRCUIT DIAGRAM & FUSES
9.1 200-240V models
Supply light &
Instrument Switch
temperature
controller thermocouple
E
L
N
SSR
hea
t
on
doo
r
switches
F1
F2
EMC Filte
r
(circuit board)
e
l
e
m
e
n
t
For models up to 16Amps the EMC filter and fuses are
integrated onto a circuit board.
9.2 100-120V models
Supply light &
Instrument Switch
temperature
controller SSR
contacto
r
F1
F2
E
L
N
door switch coil
hea
t
on
e
l
e
m
e
n
t
thermocouple
EMC filters
(circuit boards)
9.3 Fuses
F1-F3: Refer to the circuit diagram.
F1 Internal supply fuses 32mm x 6mm type F fitted on EMC filter circuit board(s)
F2 Auxiliary circuit fuses 20mm x 5mm type F fitted on EMC filter circuit board
Customer fuses Use fast-blow fuses to minimum rating shown
Model phases Volts Supply Fuse
Rating (Amps) Aux. Fuse Customer Fuse Rating
ELF 11/6B 1-phase 200-240V 10A (2 off) 2A* 10A
ELF 11/6B 1-phase 100-120V 10A (4 off) 2A 20A
ELF 11/14B 1-phase 200-240V 12.5A (2 off) 2A 12.5A
ELF 11/14B 1-phase 100-120V 12.5A (4 off) 2A 25A
* fuse not present unless overtemperature option is fitted
20 MF01