This article describes ABB power supply solutions and communication and control system technology used in the Rio Tinto Alcan ISAL Smelter Production Upgrade project. Authors: Bjarni Jonsson (RTA), Halflidi Loftsson (Staki Automation ehf.), Max Wiestner (ABB product group Aluminium)

1. ABB’s history of powering primary aluminium plants started 45 years ago. Since
then, we have supplied complete electrification solutions and substations to more
than 60 aluminium smelters worldwide. The modernization of an existing plant to the
latest standards and production and efficiency levels – performed while it is still in
operation – requires a different set of skills and competencies than building a green-
field plant. ABB has in-depth knowledge of the aluminium production process and
the experience necessary to execute complex projects – always with the objective
to keep your production running day and night. For more information, visit us at
www.abb.com/aluminium
Keeping your production running day and night?
Certainly.
Global Product Group Aluminium
5405 Baden 5 Dättwil, Switzerland
aluminium@ch.abb.com

2. Rio Tinto Alcan ISAL Smelter in Iceland Expansion Project
Introduction
The power intensive industry, which is
characterised here as manufacturers
needing more than 7 MWh/t of their
outputproduct,ishighlydependenton
the technological development of the
manufacturing companies in the areas
of products conveying, transforming,
switching and controlling power at
medium and high voltages.
It is of mutual benefit to these
companies to cooperate for continuous
improvementsofqualityandefficiency
of their products and processes. For
Rio Tinto Alcan (RTA), HSE (Health-
Safety-Environment) aspects of their
equipment and production processes
are paramount in their evaluation
for construction and operation
potential.
The engineering and production
technique of ABB in the field of SF6
insulated switchgear, has presently
reached such a level that smelters
with high HSE-demands combined
with high demands of availability
and reliability of equipment, can
take confidence in choosing medium
voltage switchgear.
The specific properties of SF6 are
further outlined below.
Electrical Properties
The excellent dielectric properties
of SF6 are attributable to the
electronegative character of its
molecule. It has a pronounced
tendency to capture free electrons
forming heavy ions with low mobility,
making the formation of electron
avalanches very unlikely. The dielectric
strength of SF6 is about 2,5 times
higher than that of atmospheric
air under the same conditions, and
this leads to space demand of only
1/10th of conventional air insulated
switchgear. This fact is decisive for
economical considerations in many
cases for voltage levels of 33 kV and
higher.
Chemical Properties
SF6 can be heated to 500°C without
decomposition in the absence
of catalytic metals. SF6 is non-
flammable. Therefore, the risk of
ignition caused by an SF6 switchgear
malfunction is practically zero, as
well as the risk of damage caused
by an external fire is as limited as
possible. The fault current interruption
capability of SF6 is excellent. In its
pure state, SF6 is nontoxic, and this is
regularly confirmed on new gas prior
to delivery, by placing mice in a gas
mixture of 80 % SF6 and 20% oxygen
for a period of 24 hours (biological test
recommended by IEC 376).
220kV AIS Footprint

3. Operation and Maintenance
The temperature within an arc in the
interruption chamber can be 15 000
K. However, only minor decomposition
remnants are present after each
interruption. CIGRE WG 23.10 is
working on an SF6 recycling guide,
covering purity criteria for SF6 SWG.
Criteria for handling of SF6 are based
on IEC 376 Standards for safety of
personnel and environment.
These factors contribute in minimizing
emissions to the atmosphere. The
normal leakage rate of HV Switchgear
can be expected to be 0,1 % - 0,5 %
per year.
Onlyauthorisedpersonnelareentitled
to work with SF6 in Iceland and other
EEA (European Economic Area – an
outer Layer of the EU) countries, as
mandated by an EU directive. Two
electricians of our substation staff
have passed through tests after
theoretical and practical training of
SF6 Gas Treatment with ABB near
Mannheim in Germany.
RTA ISAL have acquired special
equipment which is dedicated for
the sampling, testing, emptying and
refilling purposes.
RTA ISAL keeps track of its mass of
gas by annually weighing the reserve
gas and by having SF6 gas detectors in
the switchgear room and in the cable
cellar connected to the alarm system
ofthesubstation.Thepressuregauges
of each gas compartment are read off
once a week. They are also equipped
with a warning and alarm/trip level.
Environmental Aspects
SF6 does not contribute significantly
to stratospheric ozone depletion, as
it contains no chlorine, which is the
main agent in ozone catalysis, nor to
the Greenhouse effect, because the
quantities present in the atmosphere
are very small.
SF6 has infrared absorption
characteristics and is considered a
minuscule Greenhouse gas, duetoits
very long lifetime in the atmosphere.
It's contribution to global warming
however is very small, due to the
extremely low concentration of SF6
in the atmosphere.
Assessment on Engineering:
Theexperienceofmost,ifnotall,users
of SF6 switchgear, for a wide range
of operating conditions, is that this
technology has brought advantages
in performance, size, weight, global
costs and reliability.
However, for this endeavour to be
implemented,itisnecessarytoperform
a rigid risk analysis. This is carried out
jointly by knowledgeable consultants
with experience on operation, the
operators and maintenance staff of
the owner, and the manufacturer.
The findings of such risk analysis and
an SQRA (Semi Quantitative Risk
Analysis) shall form the basis for the
engineering of the switchgear.
The modern SF6 Switchgear, as
for instance manufactured by ABB
in Germany, is an extremely safe
equipment against Arc Flash. In spite
of this, the standard policy of RTA
ISAL is to control it remotely from the
control rooms.
Switchgear Room:
The IPU project (ISAL Production
Upgrade) needed space for the
installation of 13 bays of 60 kV Circuit
Breakers on double busbar. Due to
the limited space available near
the seaside, accommodating an air
insulated switchgear would not have
been possible without costly landfill.
The gas-insulated switchgear (GIS)
technology offered a feasible solution
on the available land. It was therefore
decided to construct a concrete
building beside the two 220/60 kV,
200 MVA, bays for the Step-down
transformersfeedingeachhalfof both
60 kV busbars. The link from the
ABB’s latest development in GIS has been to reduce the overall footprint drastically
Out of the total contribution of all
agents, the contribution of SF6 (less
than one part in ten thousand, 0,1
promille) is negligible.
secondary of these Step-downs is an
SF6 insulated busbar.

4. Control System
ISAL‘s main substation is supervised
by an Allen-Bradley Control Logix
controller, SuperMaster, that monitors
the status of high voltage and auxiliary
equipment, interfaces with Landsnet,
the national grid operator, and controls
transformer cooling, filter banks
and collects usage data (energy,
water consumption, etc.). Landsnet
can enforce automatic curtailment
of plant load remotely from their
National Control Centre. The required
load reduction is divided among the
potlines and adjusted for plant power
variations by the SuperMaster.
The new high voltage (HV) equipment
transformers, 220kV air-insulated
switchgear (AIS) and 60kV gas-insulated
switchgear (GIS) are controlled and
supervised by ABB Relian protective
relays. A communication gateway,
ABB COM600, passes information
between the protective relays (status,
process values, commands, etc.) and
SuperMaster, as well as the InTouch
SCADA system. In case of failure of the
plant‘s SCADA system, the COM600
can be used for supervision and control
of the HV equipment.
Each of the potlines is controlled,
protected and supervised by its
respective potline current controller.
PL1 and PL2 are controlled by state of
the art A-B Control Logix controllers
and PL3 by an ABB Controller (PSR).
The existing diode rectifer units of PL1
and PL2 are directly controlled by their
potline controllers, but rectifier units
of potline 3 are each controlled by an
ABB PSR. In case of a potline master
controller failure, all rectifier units
can be operated manually in stand-
alone mode.
The new rectifier units are each
controlled by a specialized ABB AC
800 PEC rectifier controller. The new
units fulfill the same requirement,
as the existing ones, of being able to
provide current to their potline in the
absence of a potline controller, in a
stand-alone mode.
Communications:
As the IPU project was one of integrating
new equipment with existing
equipment, several communication
paths had to be developed.
• SuperMaster / COM600
communicate through a serial
link using the IEC 60870- 5-101
protocol. A ProSoft module for
the Control Logix platform is used
This technique demanded a high
degree of precision in the civil part
and in installation of transformers
and switchgear. Avoiding cable
connection here, offers the possibility
of undistorted condition analysis
of the transformers among other
benefits.
On the GIS, the local manoeuvring
cubicles have indicators for the
position of the respective switches.
However, for safety reasons, normally
the manoeuvring of the switches takes
place at the substation’s SCADA
system, or in one of the two new
Control Rooms constructed by IPU.
The GIS-room is fitted with an
overhead crane. This was integrated
with the installation of the
switchgear, and can be utilized in
repair of the switchgear if required.
The GIS is not particularly maintenance
demanding, but ISAL intends to
incorporate it in its switchgear
maintenance scheme, recording
the pattern of the control circuit
of the trip coils, the pattern of the
main current under the interruption
period and to record the length
of the total interruption period.

5. This article was originally published in Aluminium World Journal, produced by Global Media Communication Ltd.
and software was developed to
pass information and commands
back and forth.
• InTouch SCADA / COM600 as well
as Relian / COM600
communicate over Ethernet using
the IEC 61850-8-1 protocol.
Paths 1) and 2) are completely
independent, allowing the
SuperMaster to supervise
operation and to generate
redundant alarms/ warnings in
case of break down of COM600 /
SCADA communications.
• SuperMaster / PML power
monitoring devices ION 7600
communicate through an RS-485
link using the Modbus RTU
protocol. A ProSoft module for
the Control Logix platform is
used and software was developed
to collect data from the intelligent
power meters. Supervision and
redundant control of plant power
transformer OLTC voltage
regulators (21 kV) is also
done via a Modbus link.
• InTouch SCADA / PML power
monitoring devices communicate
over Ethernet. A proprietary
Schneider Electric (ex. Power
Measurement Limited of Canada)
ION Enterprise system collects
detailed data from the ION 7600
meters, transients, sag/swell,
power quality and historical data
into a MS SQL database.
• Potline Controllers PL1 and PL2
/ AC 800 PEC rectifier controllers
communicate over Ethernet using
the EtherNet/IP protocol. The
interface on the PEC side is an
Anybus module developed by
HMS Industrial Networks. As the
EtherNet/IP Anybus module‘s
implementation allows only point
to point communication, gateways
were required for the swing units
S1 and S2, as they can be
connected to any potline and
therefore have to be able to
communicate with all the potline
controllers. The seamless
integration of the PEC controllers
of the rectifier units makes them
appear as Allen-Bradley
equipment to the rest of the world
(SCADA, MES, potline controllers,
etc.)
• Potline Controller PL3 PSR / AC
800 PEC rectifier controllers S1
and S2 communicate over an ABB
proprietary PowerLink using an
ABB PSR-PSR protocol.
• The four AC 800 PEC controllers
communicate with each other
through a dedicated redundant
PowerLink.
In Conclusion
As demonstrated by the Rio Tinto
Alcan Isal Smelter Production Upgrade
project, GIS can be integrated into
existing facilities to support expansion
and power supply for smelters
with high energy and health and
safety requirements. SF6 insulated
switchgear is an environmentally
friendly and safe technology, with
excellent operational capacities.
An upgrade can be fully tailored
through engineering solutions to work
with, and around, existing technologies,
even where space restrictions may
need to be considered.
Furthermore, the communication
and control systems are designed to
integrate seamlessly with existing ones,
to provide flexibility and economical
advantages, while securing optimal
performance.
Authors:
Bjarni Jonsson, RTA ISAL, Leader of
Electrical Services,
Haflidi Loftsson, Staki ehf, Chief
Engineer and Max Wiestner, Head of the
Aluminium business within ABB.
For more information Contact:
ABB Switzerland Ltd.
Aluminium, BU- Industrial Solutions
Max Wiestner,
Phone: +41 58 586 85
Email: max.wiestner@ch.abb.com
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