IEC 60683:2011

IEC 60683 ®
Edition 2.0 2011-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial electroheating equipment – Test methods for submerged-arc furnaces

Chauffage électrique industriel – Méthodes d'essai des fours à arc submergé

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IEC 60683 ®
Edition 2.0 2011-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial electroheating equipment – Test methods for submerged-arc furnaces

Chauffage électrique industriel – Méthodes d'essai des fours à arc submergé

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX N
ICS 25.180.10 ISBN 978-2-88912-753-5

– 2 – 60683 © IEC:2011
CONTENTS
FOREWORD . 3
1 Scope and object . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Features of the SAF system . 8
4.1 Electrical assembly of SAF . 8
4.2 Star-delta switch . 9
4.3 Types of SAF . 9
4.4 SAF process principles . 9
4.5 Types of electrodes . 9
4.6 Electrode system . 10
4.7 Water cooling . 10
4.8 Electrical connection . 10
5 Tests and general conditions . 10
5.1 General . 10
5.2 List of tests during cold state . 11
5.3 List of tests during hot commissioning and hot state . 11
6 Technical tests . 11
6.1 Electrical insulation resistance . 11
6.1.1 General . 11
6.1.2 Electrical insulation during erection . 11
6.1.3 Electrical insulation during cold test . 11
6.1.4 Electrical insulation during hot state . 12
6.2 Cooling water system . 12
6.3 Characteristics of electrode regulation. 12
6.3.1 Speed of electrode motion . 12
6.3.2 Electrode regulator dead band . 12
6.3.3 Electrode motion response time . 12
6.3.4 Current control of semiconductor converter (if applicable) . 13
6.4 Determination of electrical characteristics during operation . 13
6.5 Determination of secondary voltage . 13
6.6 Operational parameters . 13
Bibliography . 14

60683 © IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL ELECTROHEATING EQUIPMENT –
TEST METHODS FOR SUBMERGED-ARC FURNACES

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60683 has been prepared by IEC technical committee 27:
Industrial electroheating.
This second edition cancels and replaces the previous edition published in 1980 and
constitutes a technical revision.
Significant technical changes with respect to the previous edition are as follows:
– Clause 1 (Scope and object) – the types of furnaces covered by this standard are more
clearly defined.
– Clause 2 (Normative references) and Clause 3 (Terms and definitions) have been
updated and completed.
– A new Clause 4 (Features of the SAF sytem) has been added; it mainly concentrates
on the tests necessary for high voltage/high current electrical equipment in the
installation.
– Clause 5 (Tests and general conditions) and Clause 6 (Technical tests) have been
modified according to today's requirements for safe operation of a SAF.

– 4 – 60683 © IEC:2011
The text of this standard is based on the following documents:
CDV Report on voting
27/780/CDV 27/797/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
60683 © IEC:2011 – 5 –
INDUSTRIAL ELECTROHEATING EQUIPMENT –
TEST METHODS FOR SUBMERGED-ARC FURNACES

1 Scope and object
This International Standard specifies test procedures, conditions and methods according to
which the main parameters and the main operational characteristics of a submerged-arc
furnace (SAF) with rated electrical power levels above 500 kVA are established.
This standard is applicable to SAF with one or more electrodes.
In order to determine further technical or economic assessments, additional tests may be
necessary.
Tests for some special equipment for semiconductor converter controlled furnaces, such as
controlled rectifiers or controlled a.c. converters, are covered by IEC 60146-1-1.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60398, Industrial electroheating installations – General test methods
IEC 60519-1:2010, Safety in electroheating installations – Part 1: General requirements
IEC 60519-4, Safety in electroheat installations – Part 4: Particular requirements for arc
furnace installations
3 Terms and definitions
For the purposes of this document the terms and definitions given in IEC 600519-1:2010 and
the following apply.
NOTE Refer to International Electrotechnical Vocabulary, IEC 60050, for general definitions. Terms relating to
industrial electroheat are defined in IEC 60050-841.
3.1
active power
P
mean value of the instantaneous power p (in kW) taken under periodic conditions over one
period of time T (in h):
T
P= p dt
T∫
NOTE Active power instantaneous value (r.m.s.) measured at any time, including all phases.
[IEC 60050-131:2002, 131-11-42, modified]

– 6 – 60683 © IEC:2011
3.2
apparent power
S
power rating of the transformer, energizing the SAF (in MVA)
2 2
S= UI= P + Q (for single-phase SAF)

S= 3 UI (for three-phase SAF)

where
U is the voltage, r.m.s., sinusoidal value (in kV)
I is the current, r.m.s. sinusoidal value (in kA)
[IEC 60050-131:2002, 131-11-41, modified]
3.3
bottom electrode
SAFdc electrical conductive elements integrated in the SAF bottom (mainly connected as
anode)
3.4
cold state
thermal state of a furnace and its installation, when the temperature of all parts is equal to
ambient temperature
3.5
cold test
test of the entire furnace installation, including functions, connections, movements and
instrumentation, prior hot commissioning, following erection
3.6
dead band
finite range of electrical values within which a variation of the input variable does not produce
any measurable change in the output variable
[IEC 60050-351:2006, 351-24-14, modified]
3.7
electrode
part produced from conductive material to transfer the electric current to the process
NOTE For types of electrodes, see 4.5.
[IEC 60050-841:2004, 841-26-38, modified]
3.8
furnace transformer
transformer feeding the SAF with electrical energy, supplied from the high-voltage network
with suitable voltage and current ranges for operation
NOTE 1 Secondary voltage is controlled by on-load tap changer or adjusted during off-circuit.
NOTE 2 There are designs using three or more single phase transformers per furnace.
[IEC 60050-841:2004, 841-26-55, modified]

60683 © IEC:2011 – 7 –
3.9
furnace electrical losses
P
loss
losses caused by the parts of the main electrical circuit, outside the furnace vessel
NOTE Electrical losses of high voltage supply, power factor compensation (when used) or prebaking electrodes
are not included in the furnace electrical losses.
3.10
furnace
vessel which consists of bottom, shell and roof, into which the process material is charged
NOTE SAF, constructed from steel, clad with refractory, can be circular / rectangular in open, semi-closed or
closed form.
[IEC 60050-841:2004, 841-26-16, modified]
3.11
high-current line
assembly to conduct high current between transformer secondary bus bars and electrode(s),
connected in series- (and/or parallel), comprising flexible connections, bus bar system or high
current tubes, cables, electrode arms (when used) and contact clamps
3.12
hot commissioning
heating up of the furnace till a defined production is reached
3.13
hot state
thermal condition of the furnace as soon as hot commissioning is finished
3.14
main electrical circuit
electrical equipment for SAF comprising high voltage supply, power factor compensation
(when used), switchgear, transformer(s), semiconductor convertors (a.c. or d.c.) (when used),
d.c. reactor (when used), high current line, electrode systems with electrodes and burden
3.15
power factor
cos ϕ
ratio of the active power to the apparent power, measured on the primary side of the
transformer
P
cosϕ=
S
where
P is the active power (in MW)
S is the apparent power (in MVA)
NOTE In case of harmonics, power factor is determined according to IEC 60146-1-1.
[IEC 60050-131:2002, 131-11-46, modified]
3.16
reactive power
Q
total reactive electrical power (in MVAr) generated by the main electrical circuit of a SAF,
measured on all phases at the primary side of the transformer

– 8 – 60683 © IEC:2011
NOTE 1 Instantaneous value of the reactive power measured at any time, including all phases.
NOTE 2 Mean value within a time interval: i.e. generated reactive energy (in MVArh) by the power-on time (in h).
[IEC 60050-131:2002, 131-11-44, modified]
3.17
reactive power compensation
action to optimize the transmission of reactive power during operation
[IEC 60050-603:1986, 603-04-28, modified]
3.18
rectifier
device by means of which alternating current is changed into direct current for SAFdc
[IEC 60050-881:1983, 881-08-11, modified]
3.19
semiconductor converter
electronic converter for electrical power with semiconductor valve devices
NOTE SAFdc: converter to control the direct current (rectifier); SAFac: converter to control alternating current to
smooth the power input (graduator).
[IEC 60050-551:1998, 551-12-42, modified]
3.20
smoothing reactor
reactor used to reduce alternating components of a pulsating current, to minimise arc impacts
and to ensure arc stability during the process
[IEC 60050-811:1991, 811-26-21, modified]
3.21
specific electric energy consumption
quantity of electrical energy (in kWh) consumed by the SAF for the production of the final
product (in t), charging a defined mixture of specified raw materials or for the (s)melting of
charged material (in t)
3.22
submerged arc-resistance furnace
SAF
vessel in which a combined arc / resistance heating is used to melt the charged material
[IEC 60050-841:2004, 841-26-12, modified]
4 Features of the SAF system
4.1 Electrical assembly of SAF
In the electrical assembly of a SAF, the following equipment is included:
– high-voltage supply line,
– high voltage switchgear, by which the SAF can be connected/disconnected from the
electrical supply under load,
– furnace transformer(s),
– secondary bus bar system,
– semiconductor converter (a.c. or d.c.),

60683 © IEC:2011 – 9 –
– equipment for reactive power compensation and/or voltage stabilization (if supplied),
– automatic power regulation system,
– boards, panels and desks,
– control, measuring and signalling devices.
4.2 Star-delta switch
Star-delta switch(es) is/are arranged on transformer(s) HV side. It connects the transformer
HV windings to wye – or delta connection in order to modify the transformer(s) secondary
voltage range by √3. Any star-delta switch can be operated in off-circuit condition only.
NOTE When three single-phase transformers are used, the star-delta switch is installed normally inside the
transformer vessel. On single-phase transformers, the star-delta switches are installed at the high voltage
switchgear.
4.3 Types of SAF
In general the SAF is operated using the a.c. or d.c. technology.
In the SAFac, the electrical energy is conducted to the process via 3 to 6 electrodes. In some
SAFac applications (e.g. FeNi furnaces) semiconductor convertors are used for alternating
current control.
In the SAFdc, electrical energy is conducted via the anode in the bottom of the furnace
through the charge material to the cathode (electrode).
Electrical energy normally forms arcs between the electrode and the charge material or heats
up the charge material by the resistance heating (Joule effect).
4.4 SAF process principles
Processing of nonferrous metal, iron alloys, waste recycling, slag and cleaning of slag is
possible in the SAF.
It shall be differentiated between the following modes using the SAF for production:
a) 100 % burden resistance mode (electrodes submerged in the burden), e.g. for the
production of FeCr, FeSi;
b) mix of burden and slag resistance mode (electrodes submerged in burden and slag), e.g.
for slag cleaning and settling furnaces for Cu, Pb, Zn;
c) shielded arc mode (arc below electrode tip is shielded with burden and is in touch with the
slag), e.g. producing FeNi;
d) open arc mode (arc below electrode tip in direct contact with the slag), e.g. in the
TiO -slag production and waste recycling.
4.5 Types of electrodes
There are different types of electrodes, i.e.:
a) prebaked electrodes,
b) self-baking electrodes (Soederberg electrodes),
c) extrusion/composite electrodes, which are a combination of Soederberg electrodes with a
prebaked electrode as a core,
d) hollow electrode system, which allow charging of fines via the centre hole (prebaked, self-
baking).
The selection of the type of electrode depends mainly on:

– 10 – 60683 © IEC:2011
– size of the electrode,
– produced material/metallurgy,
– economic aspects such as operational costs.
4.6 Electrode system
The electrode system consists of different options as follows:
a) an upper electrode part (for slipping and holding) and a lower electrode part, which is
connected with the secondary bus bar system to conduct the electrical current to the
electrode;
b) a single electrode arm with electrode clamp which holds the electrode and conducts the
electrical energy.
NOTE 1 Occasionally the lower clamp can hold the electrode.
NOTE 2 The electrode port in the roof can be sealed by a gland.
4.7 Water cooling
Electrical equipment of the SAF can be cooled by water. Water circuits can be closed or open.
It shall be differentiated between the following water circuits:
a) furnace transformer, cooled by oil which is indirectly cooled by water,
b) secondary bus bar system including clamps,
c) electrode glands,
d) semiconductor converter for a.c. or d.c. cooled by special treated water which is indirectly
cooled by water,
e) auxiliaries,
f) d.c. reactor.
4.8 Electrical connection
High current lines of the SAFac with 3 electrodes are mostly arranged in Knapsack
connection. The furnace transformer(s) secondary windings are connected in delta at the
electrode clamps. Electrodes are connected in star with the burden or slag.
NOTE In SAFac applications with low power, the delta can be closed directly at the transformer.
5 Tests and general conditions
5.1 General
Tests shall be in accordance with the specifications given in IEC 60398 and in agreement with
IEC 60519-1 and IEC 60519-4.
Fluctuations in power supply shall be minimal and symmetry of the three phases shall be
maximized. In case it is not feasible to switch-off reactive power compensation and/or voltage
stabilization during testing, requirements are stated in this standard.
Test procedures and all measurement points are to be agreed upon between the supplier and
user.
The type of measurement equipment as well as the layout and arrangement of the
measurement points shall be shown in the test report, as far as relevant for the test.

60683 © IEC:2011 – 11 –
5.2 List of tests during cold state
The following tests shall be conducted prior hot commissioning, at regular intervals and after
repair or any modification:
a) verification of electrical insulation resistance (see 6.1);
b) check of cooling-water system (see 6.2);
c) check of electrode motion regulation system and characteristics (see 6.3);
d) measurement of secondary voltage, after transformer is connected to the electrical supply
(see 6.5).
5.3 List of tests during hot commissioning and hot state
The following tests shall be conducted following the cold test(s) during hot commissioning:
a) tuning of electrode motion regulation system and characteristics (see 6.3.1);
b) measurement of furnace electrical characteristics (see 6.1);
c) check of cooling water system (see 6.2);
d) other main operational parameters (see 6.6):
– specific electrical energy consumption;
– production rate;
– net power-on time;
– specific electrode wear.
6 Technical tests
6.1 Electrical insulation resistance
6.1.1 General
Electrical insulation of secondary low voltage circuits of SAF shall be tested in three
conditions:
a) during erection (according to IEC 60398),
b) during cold test: with electrodes mounted without charge material,
c) during hot commissioning: including charge material.
NOTE 1 Cold and hot test with water cooling in operation.
NOTE 2 Insulation tests according to the commissioning or operation manual.
6.1.2 Electrical insulation during erection
Following the erection of each individual insulated part, insulation shall be proven.
6.1.3 Electrical insulation during cold test
Following erection, electrical insulation is measured between all phases and earthing system.
In case of SAFdc, the electrical insulation measurements shall be carried out between
electrode (cathode) and earthing system, bottom electrode (anode) and earthing system and
between electrode and bottom electrode.
In case the SAF is water cooled, water shall be circulated in all cooled parts during the test.

– 12 – 60683 © IEC:2011
6.1.4 Electrical insulation during hot state
Following hot commissioning, measurements shall be carried out between all phases and the
earthing system. In case of SAFdc measurement shall be carried out between electrode
(cathode) and earthing system, bottom electrode (anode) and earthing system and between
electrode and bottom electrode.
In case the SAF is water cooled, water shall be circulated in all cooled parts during the test.
The transformer(s) shall not be energized for these tests.
Following maintenance on high current line, measurements shall be carried out between all
phases and the earthing system. In case of SAFdc measurement shall be carried out between
electrode (cathode) and earthing system, bottom electrode (anode) and earthing system and
between electrode and bottom electrode.
6.2 Cooling water system
Tests shall be carried out during normal production and SAF in hot state.
Specific information of the cooling water for the electrical parts (according to supplier’s
recommendations) shall include:
– flow rates (in m /h),
– inlet and outlet pressure (in bar),
– maximum inlet and outlet temperature (in °C),
– quality (i.e. hardness, conductivity, etc.).
Cooling water flow rate q is calculated (in m /h) using the following formula:
Q
m
q=
t
where
Q is the measured quantity of water (in m );

m
t is the time required for the test (in h).
6.3 Characteristics of electrode regulation
6.3.1 Speed of electrode motion
Electrode motion shall be measured for each electrode separately in two directions, up and
down, by means of a stop watch for a defined distance.
In case proportional valves are used, the speed shall be measured with different set points.
Measurements are made during cold test without any material charged into the furnace.
6.3.2 Electrode regulator dead band
Regulator dead band shall be adjusted during normal operation to suit smooth furnace
operations according to supplier’s recommendations.
6.3.3 Electrode motion response time
Motion response time shall be adjusted for smooth furnace operation according to supplier’s
recommendations.
NOTE Measurement is also possible using an electric control signal.

60683 © IEC:2011 – 13 –
6.3.4 Current control of semiconductor converter (if applicable)
The regulating behaviour of the current control shall be verified according to specifications of
the supplier.
6.4 Determination of electrical characteristics during operation
Primary voltage, primary current, active power, reactive power, as well as the power factor
shall be measured during operation on the primary side of the furnace transformer. In
addition, active energy and electrode current shall be measured.
Impedance Z, resistance R, reactance X can be calculated during operation on the basis of
the electrical measurements on the primary side of the furnace transformer.
6.5 Determination of secondary voltage
Following the installation of the transformer the correct function of the transformer and tap
changer shall be checked prior to hot commissioning. Therefore, the transformer shall be
energised and the secondary voltage shall be measured using all taps with primary windings
connected in star and delta, as far as applicable. Measured values shall comply with rated
values of the transformer test report.
6.6 Operational parameters
The following operational parameters shall be measured and/or calculated:
a) specific electrical energy consumption (in kWh/t) (according to supplier’s specifications),
b) production rate (in t/h) (according to supplier’s specifications),
c) net power-on time (in h),
d) electrode consumption (in kg/t).

– 14 – 60683 © IEC:2011
Bibliography
[1] IEC 60050 (all parts), International Electrotechnical
...