Malcolm Barnes. Practical Variable Speed Drives and Power Electronics

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Glossary of common terms used with AC variable speed drives 

Digital a type of signal that has two or more definite states – a binary digital

signal is a special case, which has only two states represented by logic 1

and 0

DIN Deutches Institut fűr Normierung, the main standards organization in

Germany

DIP dual in-line package, usually a group of switches used on a PCB

DOL direct-on-line, a method of starting AC induction motors by switching

them directly to the power source via a contactor

+

EIA Electronic Industries Association, a standards organization in USA that

defines the technical details of interface connections in data

communications – it recently changed its name to TIA,

Telecommunications Industries Association

EMI electro-magnetic interference, the type of electrical interference induced

by electro-magnetic fields in the vicinity of a cable

EPROM erasable programmable read only memory, a non-volatile memory,

commonly used with microprocessors to store program data – data in the

memory can be erased, usually by ultraviolet light; data is not lost when

the power is removed

EEPROM electrically erasable programmable read only memory, a non-volatile

memory, commonly used with microprocessors to store program data –

data in the memory can be erased and updated electronically; data is not

lost when the power is removed

,

Farad unit of measurement of capacitance in the metric system

FCT field controlled thyristor, a thyristor that can be turned on and off by a

voltage applied to the gate

FDM frequency division multiplexing, a technique that divides the available

frequency bandwidth into separate narrower bands to permit several

simultaneous communication channels

Fieldbus a general term given to any standard system which defines the physical

and software requirements for connecting the field devices and process

controllers together in a control system

FIP Factory information protocol, the name given to a fieldbus standard,

which includes the protocol – it was developed by French companies

FET field effect transistor, a transistor that can be turned on and off by means

of a voltage applied to the gate terminal

FSK frequency shift keying, a technique for transferring data bits by shifting

between two or more particular frequencies

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-

G giga, metric system prefix, × 10

GTO gate turnoff thyristor, a thyristor that can be turned on and off by means

of a current applied to the gate

GTR giant transistor, also called a bipolar junction transistor (BJT), which is a

power transistor rated for high currents – it can be turned on and off by

means of a current applied to the base

.

Henry unit of measurement of inductance in the metric system

HEX hexadecimal, a counting system to base 16

Hz Hertz, unit of measurement of frequency in the metric system, where

1 Hertz = 1 cycle per second

/

IC integrated circuit, an encapsulated electronic circuit, containing

miniaturized electronic components, that is designed to perform in a

particular way

IEC International Electrotechnical Commission, an international standards

organization, which specializes in electrical standards

IEAust Institute of Engineers Australia, a professional institute for engineers in

Australia

IEE Institute of Electrical Engineers, a professional institute for electrical

engineers in UK

IEEE Institute of Electrical and Electronic Engineers, a professional institute

for electronic and electrical engineers in USA

IGBT integrated gate bipolar transistor, a voltage controlled electronic

switching device, similar to a MOSFET

Impedance a combination of resistance R and reactance X, measured in ohms, that

provides an opposition to the flow of current in an electrical circuit –

units are measured in ohms

Inductance the property of an electrical circuit that opposes a current flow, causing

the current peak to lag behind the voltage peak by 90

– units are

measured in henrys

Interface a common electrical boundary between two separate devices, over which

data or other electrical signals can pass between them

I/O inputs and outputs, the connections into and out of a control device such

as a PLC, DCS, RTU, etc

ISA Instrument Society of America

Glossary of common terms used with AC variable speed drives 

ISO International Standards Organization, an organization that coordinates

standards internationally

ISP interoperable systems project, the name given to a project that is aimed at

reaching finality on a standard fieldbus system, being a compromise

between Profibus and IEC-SP50, where data communicating devices

from several manufacturers can communicate interoperably on the same

network

1

k kilo, metric system prefix, 10

kVA kilovolt-amperes, measurement of, volt × amp × 10

kW kilowatt, measurement of, watt × 10

2

LAN local area network, a data communications system, connecting several

communicating nodes, where the communication cables are shared – it is

usually restricted to a small geographic area

LCD liquid crystal display, a visual display system for operators, using liquid

crystals

LCI load commutated inverter, an inverter in which the thyristors are turned

off by the electrical behavior of the load device

LED light emitting diode, a diode that emits light when current is passing

through it

3

m meter, the unit of length in the metric system

M mega, metric system prefix, × 10

mho unit of measurement of conductance in the metric system

min minute, measurement of time = 60 sec

MODEM MOdulator-DEModulator, a device that converts digital voltage data to

frequencies suitable for transmission over an analog communications

system, such as a telephone or radio channel

MOS metal oxide semiconductor, a semiconductor device, using a specific type

of construction

MOSFET metal oxide semiconductor field effect transistor, an FET using the MOS

construction – it is a voltage controlled electronic switching device

MOV metal oxide varistor, a non-linear semiconductor device used for over-

voltage protection

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µP microprocessor, an ‘intelligent’, miniature, encapsulated processor, used

for controlling digital circuit

MTBF mean time between failures, a statistical measure of the average period

between failures of any component of a device

MTTR mean time to repair, a statistical measure of the average downtime, after a

device has failed, before it can effectively be put back into service

Multidrop network a communication network, where three or more similar devices are

connected, or ‘multidropped’, onto one network

4

NVPROM non-volatile programmable read only memory, a non-volatile

microprocessor memory, with relatively fast access, commonly used with

microprocessors to store program data – the data in the memory can be

erased and updated electronically and is not lost when the power is

removed

Nm Newton meters, the measurement of torque in the metric system

NEMA National Electrical Manufacturing Association, an association that

publishes standards for electric power, construction and testing codes in

USA

Network a communications system where several devices share the same

communications channel

Node the point where a communicating device is connected into a network

Noise the undesirable electrical signals that are induced into a communications

network from other neighboring electrical equipment carrying high

voltages or high currents – noise often results in distortion of the signal or

data errors

5

Ohm unit of measurement of resistance & impedance in metric system

Optical isolation a technique for galvanically isolating two electronic circuits by means of

a light path – the signal is transferred over the isolating barrier by using a

light-emitting source, such as an LED, and a light sensitive receiver, such

as a transistor

6

PAM pulse amplitude modulation, a modulation technique commonly used in

the inverter of older generations of AC variable speed drives to control

the amplitude of the output AC voltage

Parity an error checking system on the bits that make up a character – even

parity: parity bit is set so that the number of 1 bits are even – odd parity:

parity bit is set so that the number of 1 bits are odd

Glossary of common terms used with AC variable speed drives 

PC personal computer, a microprocessor based computer designed for

personal, office and industrial use, such as a PC-AT with 286, 386 or 486

microprocessor

PC programmable controller, a computer for use in industrial control and

which can be programmed by the user to carry out a particular control

sequence

PCB printed circuit board, a flat piece of insulation material that supports a

number of electronic components and onto which an electrical circuit has

been etched by photographic means

PLC programmable logic controller, a computer, originally designed for digital

sequence control in industrial applications – modern PLCs can also do

calculations and monitor analog inputs or control analog outputs – they

can be programmed by the user to carry out a particular control sequence

Port the terminals on a communicating device, used for input and output of

digital or analog signals

Profibus process fieldbus, the name given to a standardized field network system,

including the protocol, developed by mainly German and other European

companies

PROM programmable read only memory, a non-volatile microprocessor

memory, with relatively slow access, which usually holds a program to

control the sequence of the control device – the program stored in the

memory can be programmed once by the user but cannot be changed

thereafter; it is not lost during power down

Protocol a formal set of rules that specify all the software, flow control, error

detection and timing requirements for the exchange of messages between

two communicating devices on a network

PWM pulse width modulation, a modulation technique used in the Inverter of

many modern AC variable speed drives to control the amplitude of the

output AC voltage and to improve the shape of the current waveform

7

QA quality assurance, a management and documentation procedure aimed at

the close supervision of all aspects of design, manufacture, testing and

installation of any device or plant

QC quality control, the supervision procedures of quality assurance

8

RAM random access memory, a read/write volatile memory with fast access

to/from a microprocessor – it is used for holding temporary data during

calculation and/or implementation – data in the RAM is lost during power

down, unless battery backup is provided

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Reactance the opposition to the flow of current when an alternating voltage is

applied to an electrical circuit, due to the inductance of the circuit (X

jωL ohms) or the capacitance of the circuit (X

= 1/jωC ohms)

Resistance the opposition to the flow of current when a voltage is applied to an

electrical circuit, measured in ohms – resistance = voltage/current

RF radio frequency, which refers to high frequency waveforms above the

audible range

RFI radio frequency interference, noise whose frequencies are in the radio

frequency range

ROM read only memory, a non-volatile microprocessor memory, with

relatively slow access, which holds a program to control the sequence of

a control device – the program is stored in the ROM during manufacture,

cannot be changed by the user, and is not lost during power down

RS-232 now also called EIA-232 or TIA-232 – it is a standard that defines the

electrical and mechanical details of the physical interface between two

devices, designated DTE and DCE, employing serial binary data

interchange, over an unbalanced copper wire interface

RS-422 now also called EIA-422 or TIA-422 – it is a standard that defines the

electrical details of the physical interface between two or more devices,

employing serial binary data interchange, over a balanced differential

copper wire interface

RS-485 now also called EIA-485 or TIA-485 – it is a standard which defines the

electrical details of the physical interface between two or more devices,

employing serial binary data interchange, over a balanced differential

copper wire interface – it defines transmitters with tri-state facilities

suitable for multidropping, allowing up to 32 transmitters and 32

receivers on a network

RTD resistance temperature device, a type of thermometer sensor where the

temperature is directly proportional to the resistance

RTU remote terminal unit, an input/output terminal device that can be mounted

remotely (far away) from a programmable controller – communication

between them can take place via a wire, fiber, radio, modem, carrier or

any other suitable medium

9

SAA Standards Association of Australia, the main standards organization in

Australia

SCIM squirrel cage induction motor, a design of induction motor that is very

commonly used in industry

SCR silicon controlled rectifier, an alternative name for a thyristor

SEC State Energy Commission, name of the corporation that operates the

power supply systems in Australia

Glossary of common terms used with AC variable speed drives 

sec second, a measurement of time

Serial comms a data communications transmission mode, where the bits are transferred

sequentially on a single data channel

SI Systemes Internationale, the international system of units – SI was

adopted in 1969 as ISO Recommendation R1000

SMT surface mount technology, a technique for mounting the electronic

components on the surface of a PC board

STP shielded twisted air, usually comprising an insulated pair of copper wires,

twisted together to reduce the effect of induced noise – a conductive

shield around the twisted pair, earthed at one end only, provides

screening against capacitively coupled noise – STP can be used for data

transmission with speeds of up to 20 Mbps

:

TDM time division multiplexing, a technique which divides the available

transmission time into narrow time blocks to permit several communication

channels to use the same link – a demultiplexer is used at the receiving end

to separate the different messages

Thyristor a thyristor is a semiconductor ‘switch’ with 3 terminals, being the anode,

cathode and gate – with a forward voltage across the anode–cathode

terminals and a current applied to the gate (G), current will flow into the

anode (A) and out of the cathode (K) – the thyristor is switched off when

the anode current is reduced ≤ zero

TEFC totally enclosed fan cooled, an electric motor cooling method

TO/L thermal overload (relay), a device that monitors current and uses a bimetal

strip to simulate the thermal characteristics of an electrical load, such as an

electric motor

TPR thermistor protection relay, an electronic device that monitors the

resistance of a thermistor and closes a relay contact when the resistance

exceeds a preset level

TPU thermistor protection unit, another name for a thermistor protection relay

(see above).

TTL transistor–transistor logic, which uses positive DC logic with +5 volt =

logic 1 and 0 volt = logic 0

;

UTP unshielded twisted pair, usually comprising an insulated pair of copper

wires, twisted together to reduce the effect of induced noise – no

conductive screen is provided and it can be used for data transmission with

speeds of up to 20 Mbps

Practical Variable Speed Drives and Power Electronics

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UL Underwriters Laboratory Inc, a public testing Institute in USA

<

VDE Verband Deutcher Elektrotechniker, German Standards by DIN, which are

generally in harmony with the equivalent IEC standards

VSD variable speed drive, controls the speed of a motor, or the mechanical

device coupled to it, either mechanically or via an electronic control circuit

VSI voltage source inverter, a configuration of frequency converter where rate

of change of voltage (dv/dt) behind the inverter is limited by a large

capacitor connected in parallel across the DC link

VVVF variable voltage variable frequency (converter), where both the voltage and

the frequency output of the converter are controlled to control the speed

and limit the flux in the AC motor

=

WAN wide area network, a data communications system, connecting several

intelligent devices, where the communication channels are shared – it is

usually used over a large geographic area

Index

AC:

drives 124, 172, 214, 217

start/stop control 214

Acceleration:

linear acceleration 3

motor acceleration 48

acceleration time 48, 66

inertia load 48

maximum starting time 48

standstill 48

torque curve 48

rotational acceleration 3, 4

Ambient temperature 52–3, 66, 210

Amplifier 68, 105

linear amplifiers 68

operational amplifiers 105

Analog:

input (AI) 222

output (AO) 222

Anode (A) 71, 73, 75

ANSI 73

Anti-condensation heaters 65

flat glass-fiber tape 65

insulation see Insulation

winding impregnation 65

Asynchronous 41

Bridge:

12-pulse bridges 21

3-phase bridge 81

AC fed rectifier bridge 80, 84

diode rectifier bridge 81

blocking voltage 84

bridge connection 81

commutation period 83, 86

diode bridge 81, 88

line voltages 81

phase-to-neutral voltages 82

phase-to-phase voltage 82, 90, 99, 101

switches see Switch

full-wave 6-pulse bridge 21

half-wave 3-pulse bridge 21

inverter bridge 32, 106

rectifier see Rectifier

thyristor rectifier bridge 85

3-phase supply 90

6-pulse rectifier bridge 80–1, 89

commutation time 87–8

converter bridge 93

DC motor drive 92–4

delay angle 86–7, 90–4

diode bridge 88

displacement factor 88

excitation current 94

field magnetizing current 92

forward voltage 85–6

phase current 88–9

positive pulse 85

power factor 88

resistive-inductive load 88

sinusoidal peak 87

thyristor firing 94

triggering pulse 85

uncontrolled diode rectifier bridge 85

voltage notching 91

zero delay angle 85

Cable:

Australian standard 212

common cabling 214

communication cable 136

control cables 213

earth conductor 212

earth return cable 138

EM fields 212–3

motor cables 132, 135–6

PE terminal 213–4

power cables 114, 138

PWM voltage 213

shielded motor cables 132

shunt capacitance 131–2, 136, 138

steel wire armor (SWA) 212–3

unshielded cable 132

Cathode (K) 71, 73

auxiliary cathode 73

Centrifugal 1, 8, 10, 33, 125

fan 125

pumps 1, 8, 10, 33

Collector (C) 105, 107, 110

Commutation 76–7, 79–81, 83, 9–1

electrical stress 76

idealized commutation 80

thermal stress 76

thyristor commutation 94

transfers 80, 83

line commutated 81, 85

278 Index

self-commutated 81

gate commutated 81, 94

turn-on and turn-off periods 76

Components 68

active components 68

passive components 68

power circuit 68, 76

Converter 68–9, 80, 85–6, 89, 93–4, 105,

121–3, 125–8, 130–1, 135–6, 158, 161, 164,

211–7

6-pulse thyristor converter 85

constant power region 182–3

DC converter 69, 93–4, 126

dynamic braking 198

braking resistor 198

field weakening region 183

frequency converter 69, 77, 103, 130

IGBT converters 136

injection braking 197–8

principle 197

rotor bars 198

loadability curve 181

machine load 184

advantage 197

constant torque machine load 187

current-source inverters (CSI) 197

DC braking 197

electrical braking 196–7

flux braking 197

for starting 194

for stopping 196

generating mode 197

loadability curve 188

mechanical braking 196

problems 188

requirement 184, 194

standard TEFC 184

torque loads 188

water hammer 189

margin of safety 180

matrix converter 230

semiconductor power switches 230

universal switch 230

motor over-flux braking 198

over-voltage protection 142–3

capacitor bank 142

current limit control system 145

current overshoot 145

earth fault protection 146

heat-sink 147

junction temperature sensors 147

over-current protection 144

over-temperature protection 147

power semiconductor switching drives

143

propagation delay 145

protection trip level 147

power-speed curve 183

protection circuit 140

distribution board (DB) 140, 211

high rupturing capacity (HRC) 140

motor control center see Motor

moulded case circuit breakers (MCCB)

140

protection features 141

short-circuit protection 211

PWM converter 125–6, 128, 131, 135, 216

regenerative braking 6, 197, 201

alternative method 202

load capacity 208

nomogram 203, 206

selection principle 204

square-law 206

thyristor rectifier bridge 202

selection 178, 179

single converter 93

squirrel cage motor 180