VERDER Carbolite HZS Series Guide

MF24 –3.44
Installation, Operation &
Maintenance Instructions
1200°C Split Tube furnaces (3-zone)
types HZS & TVS
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.
Manuals are supplied separately for the furnace controllers
(and overtemperature controller when fitted).
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 9
6.0 Fault Analysis 11
7.0 Circuit Details 12
8.0 Fuses & Power Settings 15
9.0 Specifications 16

HZS, TVS
2 MF24 –3.44
1.0 INTRODUCTION
1.1 Models in the Range
The HZS and TVS range of 1200°C split tube furnaces is available in a variety of styles and
orientations. The principal varieties are:
vertical TVS, without outer casework , optionally with a wall bracket, for customer mounting;
vertical TVS as above, with a stand. One half of the furnace is fixed to the stand. This is
known as a “near hinge” arrangement;
vertical TVS with a “far hinge” arrangement. Both halves of the furnace hinge from the stand;
horizontal HZS, in an outer case;
horizontal HZS as above, but fitted to an “L-stand” which can be used in a horizontal or
vertical position.
In all the above the furnace heating section and the electrical characteristics are the same.
The standard control arrangement for these 3-zone furnaces is for slave end zone controllers to
follow the temperature of the main controller. The end zones are quite short –150mm in all
models. There are optional alternatives to this control arrangement, including independent control
of the heating zones, and the furnaces may also be ordered with equal zone lengths. Note that the
original design intent in these “3-zone” models is to achieve an extended uniform single zone.
When independent control is fitted, some temperature difference can be achieved, but Carbolite
can make no specific warranty as to the extent to which this is possible.
1.2 Voltage and Power Control
All models in this range, from March 2001, are supplied with heating elements designed for use
over the voltage range 200V-240V or 3-phase equivalents. The Carbolite control system
incorporates a “power limit” which effectively limits the voltage to 208V. It is most important that
any alternative system provided by the customer should be able to limit the power accordingly. See
sections 3.7 and 8.2.
1.3 Switches and Lights
1.4 Warning Symbols
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
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.
DANGER –read any
warning printed by this
symbol.
Heat Switch: the switch disconnects power to the heating elements; unless
this switch is off there is a danger of electric shock when inserting objects
into the furnace

HZS, TVS
MF24 –3.44 3
2.0 INSTALLATION
2.1 Unpacking & Handling
When unpacking or moving the furnace always lift it by its case or main body. Never lift it by its
insulation or by a fitted work tube. If possible use two people to carry the furnace and remote
control box. Remove any packing material from inside the furnace before use.
If an optional or special stand is separately supplied, assemble the furnace on to it. These models
may be supplied for customer mounting and may require customer preparation of mounting
components before installation.
NOTE: This product contains Refractory Ceramic Fibre (better described as Alumino Silicate
Wool) for precautions and advice in handling this material see the ‘Repairs and Replacements’
section.
2.2 Siting
Place the furnace in a well ventilated room, away from other sources of heat, and on a surface
which is resistant to accidental spillage of hot materials. Do not mount the furnace on an
inflammable surface.
Ensure that there is free space around the furnace. Do not obstruct any of the vents in the control
box: they are needed to keep the controls cool.
Ensure that the control box is placed in such a way that it can be quickly switched off or
disconnected from the electrical supply - see below.
2.3 Setting Up
If the furnace is supplied with a work tube or any accessories fit these into position.
For optimum temperature uniformity, insulating plugs should be placed in the tube ends as shown
in fig.1. With a long inner work tube, the stem of the plug assembly should line up with the end of
the tube as in fig.2. Alignment of radiation shields is similar to that of plugs. With these models,
split end plugs are supplied; unless ordered for a specific tube size, these require shaping to fit the
tube or work piece: use a round file.
If stainless steel seals with gas inlets are supplied they are to be fitted as shown in fig.3; the stem
of any insulating plug should touch the seal. Stainless steel seals for vertical use: a hook and eye
arrangement holds the upper insulating plug assembly; alternatively a gland nut.
Horizontal models: if heavy fittings are to be clamped to the end of an extended work tube they
can increase the bending stress at the centre of the tube. Support such fittings in such a way that
expansion of the tube is allowed.
If a metal work tube is being used in the furnace, ensure that it is earthed for operator safety.

HZS, TVS
4 MF24 –3.44
2.4 Electrical Connections
Connection by a qualified electrician is recommended.
The furnaces 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 can be
supplied for three phase use (and if so, are “universal” – see section 2.5).
Check the furnace 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.
If the actual supply is not the same as the voltage on the label, then the controller power limit may
need to be adjusted: set the Heater Switch to off, connect the furnace and see section 3.7.
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.
Furnace with supply cable: either wire directly to an isolator or fit with a line plug.
Furnace without supply cable: a permanent connection to a fused and isolated supply should be
made to the internal terminals after temporary removal of the furnace 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)
Do not connect a furnace ordered for three phase use to a single phase supply or to the wrong type
of three phase supply –except as indicated in sections 2.5 and 7.9.
2.5 “Universal Wiring” (year 2000 onwards)
When (and only when) ordered for 3-phase use these furnaces are supplied in a form in which they
can be easily rewired between 1-phase and 3-phase supplies. This applies to 3-phase+N and 3-
phase delta in the ranges 380/220V–415/240V and 200-240V, but does not apply to 3-phase star
without neutral (e.g 380V or 440V).
To alter the configuration, remove the control box back panel and alter the connections between
the supply terminal block and the EMC filters, using the appropriate diagram from section 7.9.
Models ordered for single phase only are not affected and cannot be converted to 3-phase.
If in doubt, please consult Carbolite.

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MF24 –3.44 5
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 3-zone Control Methods
The models in this manual are typically designed to achieve an extended uniform temperature zone
by the use of three control zones, with he control zones linked so that end zones follow the central
zone in a master-slave approach; there are two ways of doing this. Alternatively, independent
control zones may be ordered. There are thus three control methods (A, B & C).
A. Back-to-Back Thermocouples
This is the most commonly supplied option.
The central zone of the work tube is controlled directly by the central temperature controller. Each
end zone thermocouple is wired in opposition to a central reference thermocouple, and the
resulting small voltage difference when the zones are at different temperatures is used by the end
zone controller. The circuit diagram in section 7.0 shows the thermocouple arrangement.
Set the "setpoint" of the end zone controllers to zero. Alternatively, a small temperature difference
(offset) can be created by setting a non-zero value, but the sum of the main controller set-point and
the slave controller offset MUST NOT exceed the furnace maximum temperature.
To alter the setpoint (with the display at “home”), press Down or Up once to display the
setpoint; press again or hold down to adjust it. The display returns to the measured temperature
offset when no key is pressed for 0.5 seconds.
Sometimes a furnace using this type of control does not cool down –this may depend on the
customer work load. The end controllers strive to remain at the central temperature, and prevent
cooling. Should this occur, please contact Carbolite’s technical department.
2132 Slave Controller Navigation Diagram
B. Retransmission of Setpoint using Broadcast comms
When this is ordered there are three independent thermocouples connected to the three controllers.
The controllers are linked together, the central controller communicating the desired setpoint to the
end controllers.
Additional communication modules are fitted in the controllers, rather than an additional
thermocouple as in A. The communication between the controllers of the Eurotherm 3000 series is
known as Broadcast comms.
It is possible to switch off the linked control and allow the controllers to work independently. In
level 2 of the end zone controllers (see controller operating instruction), scroll to L-r. Where the
end zone controller is a 3216 use the up down and select NO. Where the end zone controller
Home
List
Access
List
°C/F/k
ACCS
°C/F/k
codE
0.0
Zone temperature
difference; use  /  to
access offset “setpoint”
home list
for factory access to lists
and parameters not
available to the operator


OP.Hi
Output
List
oP

power limit
setting, if
present

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6 MF24 –3.44
is a 3508 use the up down to select SP1, (SP1 = Local, and SP2 = Remote). There is no
need to alter the centre controller.
It is possible to use local trim in the end zone controllers to enter a positive or negative adjustment
from the centre zone temperature. Once entered this trim will always be added or subtracted from
the retransmitted set temperature. In level 2 of the end zone controller (see controller operating
instruction), scroll to LOC.T (local trim) and use the up down enter the desired positive or
negative difference to be added to the end zone set temperature. There is no need to alter the
centre controller.
C. Independent Control
In this case the three controllers are completely independent. Note that it is not possible to
maintain very different zone temperatures because of heat transfer within the work tube.
3.2 Operating Cycle
The furnace is fitted with an Instrument switch. The switch cuts off power to the control circuit.
There is also a Heater switch which can be used to disconnect power to the elements.
Connect the furnace to the electrical supply.
Operate the instrument switch to activate the temperature controller. The controller becomes
illuminated and goes through a short test cycle.
Control methods A & B: Set the slave (end zone) controllers to the desired offset temperature,
usually zero. Set the main (central) temperature controller to the desired setpoint or program. See
section 3.1 and/or the separate manual(s) for the controller(s).
Control method C: Set the three controllers to the desired temperatures. See the separate manual(s)
for the controller(s).
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.
Switch on the Heater switch, located on the instrument panel. Unless a time switch is fitted and is
off, the furnace starts to heat up. The Heat light(s) glow steadily at first and then flash as the
furnace approaches the desired temperature or a program setpoint.
Overtemperature option only. If the overtemperature trip operates then an indicator in the over-
temperature controller flashes, and the heating elements are isolated. Find and correct the cause
before resetting the overtemperature controller according the instructions supplied.
To switch off power to the heating elements, use the Heater Switch. To switch the furnace off, use
both the Heater switch and the Instrument switch. If the furnace is to be left off unattended, isolate
it from the electrical supply.
3.3 General Operating Advice
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 is shown on the furnace
rating label and on the back page of this manual.
Lightweight ceramic fibre insulation can easily be marked by accidental contact. Some fine cracks
may be visible on the surface of the insulation, or may develop in the surface of the chamber due
to progressive shrinkage of the insulation materials. Cracks are not usually detrimental to the
functioning or the safety of the furnace.
3.4 Operator Safety
The ceramic materials used in furnace manufacture become electrically conductive to some extent
at high temperatures. In these models there are partially exposed heating coils in the chamber and
there is danger of contact even with the furnace closed. DO NOT use any conductive tools within
the work tube without isolating it. If a metal work tube is used, it must be earthed (grounded).

HZS, TVS
MF24 –3.44 7
The furnace incorporates a safety switch which interrupts the heating element circuit when it is
opened. This prevents the user touching a live heating element, but also prevents the furnace from
heating up when open. The operation of this switch should be checked periodically –see section
4.1.2.
There is also a “Heater switch” which may be used to interrupt power to the elements. Switch off
the Heater switch whenever loading or unloading the furnace. The elements are isolated when the
Heater switch is OFF.
Avoid burns: furnace surfaces can be hot. Before you remove a hot object from the furnace make
sure you have a safe place to put it down.
3.5 Tube Life
A ceramic work tube may be cracked if workpieces are inserted too
quickly or at temperatures below 900°C (when the tube is more
brittle). Large pieces should also be heated slowly to ensure that large
temperature differences do not arise.
Poor thermal contact should be encouraged between the workpiece
and the tube; crucibles or boats should be of low thermal mass and
should have feet to reduce the contact with the tube (fig. 4).
Do not set too high a heating rate. Large diameter tubes are more susceptible to thermal shock than
smaller. Tubes which extend beyond the heated part of the furnace are more at risk. A general rule
for maximum heating rate is 400/internal diameter (°C/min); for 75mm i/d tubes this comes to 5°C
per minute. The controller can be set to limit the heating rate.
3.6 Pressure
Work tubes are not able to accept high internal pressure. When gas seals or similar fittings are in
use, the gas pressure should be restricted to a maximum of 0.2 bar (3 psi). A pressure of about half
of that should normally be sufficient to achieve the desired flow rate. The customer must ensure
that the exhaust path from the tube is not blocked, so that excess pressure does not occur.
3.7 Power Adjustment
The furnace control system incorporates electronic power limiting. The power limit parameter
OP.Hi is accessible, and can be used to adjust the furnace to the actual supply voltage.
The models covered by this manual (March 2001 onwards) are designed for use over the range of
voltages 200V-250V (or, if ordered, 100V-125V), and the power limit parameter is set
accordingly. These models may be relocated to a different voltage within the range: the power
limit should be reset to match the voltage. See section 8.2.
To alter the power limit
Set the Heater Switch to Off to prevent heating while adjusting the power limit.
Press Page until oP (output list) is displayed. Press Scroll until OP.Hi (Output High) is
displayed. Press Down or Up once 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 or Up .
A power setting of zero prevents the furnace from heating: useful for demonstrating the controls
without taking power.
Do not increase the power limit simply “to get more power”. The elements could burn out, or a
fuse could blow.
3.8 Running at Low Temperatures
The power limit may be adjusted to a low level to achieve better control when running the furnace
at a low temperature. No hard and fast rules can be given, but, as an example, to run at

HZS, TVS
8 MF24 –3.44
temperatures only up to 600°C try a power limit of 50%. Control stability may fall off again if a
setting below about 40% is used.
Before changing the power limit, record its factory setting for possible future use.
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
Check the furnace interior. If soot deposits have formed, remove by heating up to maximum
temperature for one hour without load.
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 safety switch operation mentioned in 3.3 should be checked periodically to ensure that heating
elements are isolated when the furnace 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.
A qualified electrician should check that the supply to the heating elements is cut, with and
without power being on, when the furnace is open partially and fully; it is important that isolation
is not just marginally achieved. The check is best made on the element terminals after removal of
the covers: probing the element surface inside the furnace could be inconclusive because of surface
oxidation. Note that all live supply wires of a 3-phase supply, and both live and neutral of a 1-
phase supply, should be isolated when the door is opened.
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 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. These items can be supplied by Carbolite.
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 of each type of
thermocouple, one solid state relay, and two heating elements (models /900: 2 of each type).
When ordering spares please quote the model details as requested above.

HZS, TVS
MF24 –3.44 9
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 Warning - 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. These materials
may be in the form of blanket or felt, formed board or shapes, mineral wool slab or loose fill wool.
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 fibrous dust may cause respiratory disease.
When handling the material always use an approved respiratory protection equipment
(RPE-i.e. FFP3), eye protection, gloves and long sleeved clothing.
Avoid breaking up waste material. Dispose of waste 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 Association
representing the High Temperature Insulation 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 Temperature Controller Replacement
301. This controller is fitted to the back of the control panel; in many models this can be separated
from the base by removal of two screws. Refer to the detailed instructions supplied with the
replacement controller.
Before handling the controller: wear an anti-static wrist strap or otherwise avoid any possibility
of damage to the unit by static electricity.
2132, 3216, 3508 etc. Ease apart the two lugs at the side; grip the instrument and withdraw it from
its sleeve; push in the replacement.
5.4 Solid-state Relay Replacement
Disconnect the furnace from the supply and remove the back panel from the base or control box..
Make a note of how the wires are connected to the solid state relay, and disconnect them.
Remove the solid state relay from the base panel or 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.
Replace the removed panel.
5.5 Thermocouple Replacement
The coverings and guards which must be removed to gain access to the thermocouples depend on
the model, and any mounting options or fittings. Study the furnace layout and ask if in doubt.
Disconnect the furnace from the supply, and remove covers and guards as necessary.

HZS, TVS
10 MF24 –3.44
Make a note of the thermocouple connections Type N colour codings are: negative = white,
positive = pink (old models: negative = blue, positive = orange).
Disconnect the thermocouple from its terminal block and withdraw it from its sheath (the narrow-
bore built-in tube) and remove any broken bits of thermocouple.
Bend the new thermocouple carefully to match the shape of the original (working from the
terminal end). Should the overall length differ from that of the original provided, ensure that the
tip ends up the same distance from the end as it did in the original.
Insert the new thermocouple into position, restoring any removed porcelain spacers, and ensuring
correct polarity.
Re-assemble the furnace.
5.6 Fuse Replacement
Fuses are marked on the circuit diagram (section 0) with type codes, e.g. F1, F2. A list of the
correct fuses is given in section 8.1. The fuses fitted depend on model and voltage.
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, with access by removal of the control box back panel.
5.7 Element Replacement
Please see safety note 5.2 - please wear a face mask.
HZS and TVS with far hinge: Remove the three screws from each end and lift out the half-circular
insulation assembly. Make a plan of all the cable connections and disconnect the cables.
Remove the thermocouples by withdrawing them from the sheaths built into the elements. Remove
the plates through which the element tails are located. Remove the keep plates from each side of
the insulation assembly. Lift out the element to be replaced; save any insulation sleeves for
possible reuse.
Bend or cut the new element tails as necessary, and fit any insulation sleeves; feed the tails through
and fit the element into place.
Refit the keep plates on each side. Refit the tail termination plates, ensuring that the element tails
do not touch any metal parts. Refit the thermocouples and cnnect all the wiring according to the
plan previously made to complete the reassembly.
Check that the furnace is controlling properly to rule out the possibility that the element failed
because of a fault in the control system.
HZS & TVS Elements each element is a half-cylinder
HZS & TVS 12/600
200-240V
4 pairs in parallel,
each pair 2 in series
100-120V
8 elements in parallel
HZS & TVS 12/600E
(equal zones)
200-240V
3 pairs in parallel,
each pair 2 in series
100-120V
6 elements in parallel
HZS & TVS 12/900
200-240V
5 pairs in parallel,
each pair 2 in series
100-120V
10 elements in parallel
HZS & TVS 12/900E
(equal zones)
200-240V
6 pairs in parallel,
each pair 2 in series
100-120V
12 elements in parallel
12/600 has 4 pairs of 150mm length; 12/600E has 3 pairs of 200mm length
12/900 has 2 pairs of 150mm (ends) and 3 pairs of 200mm (centre)
12/900E has 6 pairs of 150mm elements;
Where both 200mm and 150mm are fitted, the 150mm elements are at the ends.