Download glossary of technical terms

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GLOSSARY OF TECHNICAL TERMS
This glossary contains definitions of certain terms used in this document in connection with our
Company and our business. Some of these terms may not correspond to standard industry definitions.
“AC”
alternating current, an electric current whose direction reverses
cyclically
“anode saturable reactor”
an essential protective component integrated in HVDC convertor
valves, used to limit the high rise rate of currents and protect
against current surges, and to prevent an off-line convertor thyristor
from opening in error which can be caused by a voltage surge
“capacitor”
a passive electronic component consisting of a pair of conductors
separated by an insulator. When a potential difference in voltage
exists across the conductors, an electric field is present in the
insulator. This field stores energy and produces a mechanical force
between the conductors. Capacitors are used in electronic circuits to
block the flow of DC while allowing AC to pass, to filter out
interference, to smooth the output of power suppliers, and for other
purposes
“capacitor bank”
a system comprising several capacitor units and other electric
components mounted on a frame
“carrier”
a particle that carries electric charge in a semiconductor. There are
two types of carriers: (i) electrons, which carry a negative charge;
and (ii) holes, which are travelling vacancies in the electron
population of the semiconductor and carry a positive charge
“convertor”
an electric device which converts electric power from the form it is
supplied to the form it is needed. The device that converts from AC
to DC is called rectifier, while the device that converts DC to AC
is called inverter
“convertor valve”
the key part of HVDC project, generating DC voltage through
connecting the 3-phase AC voltage to DC terminal and realising the
control of power
“current/voltage sensor”
a device that measures current and voltage, respectively, at
specified points in a power electronic system. A current/voltage
sensor is required for the control and protection of a power
electronic system, and used in many applications like wind energy,
solar energy, electric railway and other industrial applications
“DC”
direct current, an electric current whose direction is constant
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THIS WEB PROOF INFORMATION PACK IS IN DRAFT FORM. The information contained herein is incomplete and subject to change. This
Web Proof Information Pack must be read in conjunction with the section headed “Warning” on the cover of this Web Proof Information Pack.
GLOSSARY OF TECHNICAL TERMS
“deionised water cooling system”
a system that uses deionised water as cooling media. The cooling
system dissipates heat from the heat sink to the heat exchanger,
where the media is cooled down by dissipating heat to the outside
environment or a secondary cooling circuit. Depending on the
requirements regarding purity of the cooling media, a water
treatment circuit is added to the system
“electric locomotive”
a locomotive powered by electricity drawn from a power grid
“electrified railway”
railway with locomotives and MUs powered by electricity drawn
from a power grid
“EMU” or “electric multiple unit”
an electrically driven train consisting of more than one passenger
carriage. Instead of using a locomotive, the driving power is
distributed to several passenger carriages equipped with motors to
achieve greater traction and flexible grouping
“film”
the main material used for the insulation between the electrodes of
a capacitor
“freight wagon”
a rail vehicle primarily used for carrying goods
“fuse”
an electric device which protects other electric equipment from
over-current
“GTO”
gate turn-off thyristor, a special type of thyristor and a high-power
semiconductor device. GTOs are fully controllable switches which
can be turned on and off by their third lead, the GATE lead
“heat sink”
a semiconductor device, which dissipates heat generated by a
semiconductor device. In many applications the heat sinks are water
cooled, and therefore connected to the water circuit of the cooling
system
“high power”
power in the range from 0.5MVA to 36MVA
“high-speed train”
a train with an operating speed exceeding 200 km per hour
“HVDC” or “high-voltage,
direct current”
a HVDC electric power transmission system using direct current for
the bulk transmission of electrical power. For long-distance
distribution, HVDC systems are less expensive and suffer lower
electrical losses
“HV power capacitor”
a capacitor with a rated voltage of 1 kilovolt or higher
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THIS WEB PROOF INFORMATION PACK IS IN DRAFT FORM. The information contained herein is incomplete and subject to change. This
Web Proof Information Pack must be read in conjunction with the section headed “Warning” on the cover of this Web Proof Information Pack.
GLOSSARY OF TECHNICAL TERMS
“IGBT” or “insulated gate bipolar
transistor”
a power semiconductor device or module used to switch electric
power in electrical appliances. IGBTs are noted for their high
efficiency and fast switching and are used in electric traction,
windmills, power transmission systems and other convertor
applications
“IGBT driver” or “gate driver”
the controlling device of an IGBT
“IGBT power module”
a device comprising IGBT and other electric components and
applied in a convertor
“IGCT”
integrated gate-commutated thyristor, a power semiconductor
electronic device which is used for switching electric current in
industrial equipment and related to the gate turn-off (GTO)
thyristor
“inductance”
the ability of a reactor to store magnetic energy and measured by its
inductance, in units of henries (H)
“km”
kilometer
“kV”
kilovolt
“kw”
kilowatt
“kwh”
kilowatt hour
“locomotive”
a driving vehicle that mobilises passenger carriages and freight
wagons but does not carry passengers or freight (also known as the
head of a train)
“MW”
megawatt
“MU”
a fixed arrangement of cars which are equipped with driving
carriages, non-powered trailers and occasionally, controlling
carriages
“osmosis”
diffusion of water through a semi-permeable membrane. More
specifically, it is the movement of water across a semi-permeable
membrane from an area of high water potential (low solute
concentration) to an area of low water potential (high solute
concentration). It is a physical process in which a solvent moves,
without input of energy, across a semi-permeable membrane
(permeable to the solvent, but not the solute) separating two
solutions of different concentrations
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THIS WEB PROOF INFORMATION PACK IS IN DRAFT FORM. The information contained herein is incomplete and subject to change. This
Web Proof Information Pack must be read in conjunction with the section headed “Warning” on the cover of this Web Proof Information Pack.
GLOSSARY OF TECHNICAL TERMS
“passenger carriage”
a car designed for the conveyance of passengers by rail and the
provision of service, which is primarily used by a passenger train
“power industry”
comprises power generation and power transmission and
distribution. Power generation refers to the process of creating
electricity from other forms of energy. Power transmission and
distribution refer to the movement of energy from the place of
generation to the place of application
“rail vehicles”
refers to locomotives, passenger carriages, freight wagons, MUs
and large railway maintenance vehicles
“rapid transit system”
urban mass rapid transit system, including subways and light rails
“reactor”
a passive electrical component, also called inductor, which stores
energy in a magnetic field created by the electric current passing
through it. The main part of a reactor is the conducting element
shaped as a coil with loops helping create a strong magnetic field
inside the coil. In electrical transmission systems, inductors are
used to depress voltages from lightning strikes and to limit
switching currents and fault currents. Two or more inductors which
have coupled magnetic flux form a transformer, which is a
fundamental component of every electric utility power grid
“rectifier”
an electrical device that converts AC to DC in a process known as
rectification
“rolling stock”
refers to all types of rail vehicles and rapid transit vehicles
including locomotives, passenger carriages, freight wagons, MUs,
light rail cars and metro cars
“semiconductor”
a material having an electrical conductivity between that of a
conductor and an insulator. Devices made from semiconductor
materials are the foundation of modern electronics including radio,
computers, telephones, and many other devices. In semiconductors,
current can be carried either by the flow of electrons or by the flow
of positively-charged holes in the electron structure of the material
“SVC”
an electrical device used for providing fast-acting reactive power
on high-voltage electricity transmission networks, regulating
voltage and stabilising the system
“surge current”
refers to the instantaneous rise of an electric current
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THIS WEB PROOF INFORMATION PACK IS IN DRAFT FORM. The information contained herein is incomplete and subject to change. This
Web Proof Information Pack must be read in conjunction with the section headed “Warning” on the cover of this Web Proof Information Pack.
GLOSSARY OF TECHNICAL TERMS
“thyristor”
a solid-state semiconductor device with four layers of alternating N
and P-type material and acts as a bistable switch, which conducts
when the gate receives a current pulse and continues to conduct for
as long as it is forward biased
“urban metro”
a single train unit that can be arranged into a subway train and
operated on subway lines, including powered vehicles and nonpowered trailers
“var” or “VAR”
volt-ampere reactive (var) is a unit used to measure reactive power
in an AC electric power system in alternating current power
transmission and distribution
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