Siemens SIRIUS 3RW30 User manual

Soft starters
SIRIUS 3RW30 / 3RW40
Manual •01/2010
Industrial Controls
Answers for industry.

Industrial Controls
Soft starters
SIRIUS 3RW30 / 3RW40
Manual
01/2010
535 1995-02 DS01
Introduction 1
Safety information 2
Product description 3
Product combinations 4
Functions 5
Application planning 6
Installation 7
Installation / mounting 8
Connecting 9
Operation 10
Configuration 11
Commissioning 12
Technical data 13
Dimension drawings 14
Typical circuit diagrams 15
Accessories 16
Appendix A

Legal information
Warning notice system
This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent
damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert
symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are
graded according to the degree of danger.
DANGER
indicates that death or severe personal injury will result if proper precautions are not taken.
WARNING
indicates that death or severe personal injury may result if proper precautions are not taken.
CAUTION
with a safety alert symbol, indicates that minor personal injury can result if proper precautions are not taken.
CAUTION
without a safety alert symbol, indicates that property damage can result if proper precautions are not taken.
NOTICE
indicates that an unintended result or situation can occur if the corresponding information is not taken into account.
If more than one degree of danger is present, the warning notice representing the highest degree of danger will be
used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to property
damage.
Qualified Personnel
The product/system described in this documentation may be operated only by personnel qualified for the specific
task in accordance with the relevant documentation for the specific task, in particular its warning notices and safety
instructions. Qualified personnel are those who, based on their training and experience, are capable of identifying
risks and avoiding potential hazards when working with these products/systems.
Proper use of Siemens products
Note the following:
WARNING
Siemens products may only be used for the applications described in the catalog and in the relevant technical
documentation. If products and components from other manufacturers are used, these must be recommended or
approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and
maintenance are required to ensure that the products operate safely and without any problems. The permissible
ambient conditions must be adhered to. The information in the relevant documentation must be observed.
Trademarks
All names identified by ® are registered trademarks of the Siemens AG. The remaining trademarks in this
publication may be trademarks whose use by third parties for their own purposes could violate the rights of the
owner.
Disclaimer of Liability
We have reviewed the contents of this publication to ensure consistency with the hardware and software described.
Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the information in this
publication is reviewed regularly and any necessary corrections are included in subsequent editions.
Siemens AG
Industry Sector
Postfach 48 48
90026 NÜRNBERG
GERMANY
Ordernumber: 3ZX1012-0RW30-1AC1
®‹ 01.2010
Copyright © Siemens AG 2009.
Technical data subject to change

SIRIUS 3RW30 / 3RW40
Manual 01/2010, 535 1995-02 DS01 5
Table of contents
1 Introduction ............................................................................................................................................. 11
1.1 Important notes.......................................................................................................................... 11
2 Safety information .................................................................................................................................. 13
2.1 Before commencing work: Isolating the equipment from the supply system and ensuring that it
cannot be reconnected. ............................................................................................................. 13
2.2 Five safety rules for work in or on electrical systems ................................................................ 13
3 Product description ................................................................................................................................ 15
3.1 Fields of application................................................................................................................... 15
3.2 Basic physical principles of a three-phase induction motor....................................................... 15
3.2.1 Three-phase induction motor ..................................................................................................... 15
3.3 Functional principle of the SIRIUS 3RW30 and 3RW40 soft starters........................................ 17
3.3.1 Method of operation of a two-phase controlled soft starter ....................................................... 20
3.3.2 Starting current asymmetry ....................................................................................................... 21
3.3.3 Applications and use ................................................................................................................. 22
3.4 Comparison of device functions ................................................................................................ 24
4 Product combinations ............................................................................................................................ 25
4.1 SIRIUS modular system ............................................................................................................ 25
5 Functions ................................................................................................................................................. 27
5.1 Start modes ............................................................................................................................... 27
5.1.1 Voltage ramp ............................................................................................................................. 27
5.1.2 Current limiting and ramp-up detection (3RW40 only) .............................................................. 29
5.2 Stop modes ............................................................................................................................... 30
5.2.1 Stop without load (3RW30 and 3RW40) .................................................................................... 31
5.2.2 Soft stop (3RW40 only) ............................................................................................................. 31
5.3 Motor protection / intrinsic device protection (3RW40 only) ...................................................... 32
5.3.1 Motor protection function ........................................................................................................... 32
5.3.2 Intrinsic device protection (3RW40 only) ................................................................................... 35
5.4 Functions of the RESET buttons ............................................................................................... 36
5.4.1 SIRIUS 3RW40 2, 3RW40 3, and 3RW40 4 soft starters .......................................................... 36
5.4.2 SIRIUS 3RW40 5 and 3RW40 7 soft starters ............................................................................ 38
5.4.3 Other functions of the RESET button ........................................................................................ 39
5.5 Functions of the inputs .............................................................................................................. 40
5.5.1 Start input (terminal 1) on 3RW30 and 3RW40 2 to 3RW40 4 .................................................. 40
5.5.2 Start input (terminal 3) on 3RW40 5 and 3RW40 7 ................................................................... 40
5.5.3 Thermistor input / connection on 3RW40 2 to 3RW40 4 ........................................................... 41
5.6 Functions of the outputs ............................................................................................................ 41
5.6.1 3RW30: Output terminal 13 / 14 ON .......................................................................................... 41
5.6.2 3RW40: Output terminals 13 / 14 ON / RUN and 23 / 24 BYPASSED ...................................... 42

Table of contents
SIRIUS 3RW30 / 3RW40
6Manual, 01/2010, 535 1995-02 DS01
5.6.3 3RW40: Group fault output at terminal 95 / 96 / 98 OVERLOAD / FAILURE ............................ 43
5.7 Diagnostics and fault signals ..................................................................................................... 44
5.7.1 3RW30: LEDs and troubleshooting ...........................................................................................44
5.7.2 3RW40: LEDs and troubleshooting ...........................................................................................46
6 Application planning .............................................................................................................................. 51
6.1 Application examples................................................................................................................. 51
6.1.1 Roller conveyor application ........................................................................................................ 51
6.1.2 Hydraulic pump application ........................................................................................................ 52
7 Installation ............................................................................................................................................... 53
7.1 Installing the soft starter............................................................................................................. 53
7.1.1 Unpacking .................................................................................................................................. 53
7.1.2 Permissible mounting position ................................................................................................... 53
7.1.3 Mounting dimensions, clearances, and assembly type ............................................................. 54
7.1.4 Assembly type: Standalone assembly, side-by-side assembly, direct mounting ....................... 55
7.1.5 Installation requirements ............................................................................................................ 56
8 Installation / mounting ............................................................................................................................ 57
8.1 General information ................................................................................................................... 57
8.2 Five safety rules for work in or on electrical systems ................................................................ 58
8.3 General feeder assembly (type of coordination 1)..................................................................... 59
8.4 Soft starter with line contactor (type of coordination 1).............................................................. 60
8.5 Soft starter assembly with type of coordination 2 ...................................................................... 61
8.6 Capacitors to improve the power factor ..................................................................................... 62
8.7 Maximum cable length............................................................................................................... 63
9 Connecting .............................................................................................................................................. 65
9.1 Electrical connection.................................................................................................................. 65
9.1.1 Control and auxiliary terminals .................................................................................................. 65
9.1.2 Main circuit connection .............................................................................................................. 65
10 Operation ................................................................................................................................................. 69
10.1 Operator controls, displays, and connections on the 3RW30.................................................... 69
10.2 Operator controls, displays, and connections on the 3RW40.................................................... 70
11 Configuration .......................................................................................................................................... 73
11.1 Configuration in general............................................................................................................. 73
11.1.1 Configuration procedure ............................................................................................................ 73
11.1.2 Selecting the optimum soft starter ............................................................................................. 74
11.2 Startup class.............................................................................................................................. 76
11.2.1 Application examples for normal starting (CLASS 10) with 3RW30 and 3RW40 ...................... 77
11.2.2 Application examples for heavy-duty starting (CLASS 20): 3RW40 only .................................. 78
11.3 ON time and switching frequency .............................................................................................. 79
11.4 Reducing the rated data ............................................................................................................ 80
11.5 Installation altitude and ambient temperature............................................................................ 80

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Manual, 01/2010, 535 1995-02 DS01 7
Table of contents
11.6 Calculating the permissible switching frequency....................................................................... 81
11.6.1 Table of permissible assembly combinations with switching frequency factors ........................ 81
11.6.2 Calculating the switching frequency (example) ......................................................................... 84
11.7 Configuration aids...................................................................................................................... 86
11.7.1 Online configurator .................................................................................................................... 86
11.7.2 Win-Soft Starter selection and simulation software ................................................................... 86
11.7.3 Technical Assistance ................................................................................................................. 86
11.7.4 SIRIUS soft starter training course (SD-SIRIUSO) .................................................................... 87
11.8 Order number system for the 3RW30........................................................................................ 88
11.9 Order number system for the 3RW40........................................................................................ 89
12 Commissioning ....................................................................................................................................... 91
12.1 Before commencing work: Isolating the equipment from the supply system and ensuring that it
cannot be reconnected. ............................................................................................................. 91
12.2 Commissioning the 3RW30 ....................................................................................................... 92
12.2.1 Commissioning procedure ......................................................................................................... 92
12.2.2 Quick commissioning of the 3RW30 and optimization of the parameters ................................. 93
12.2.3 Setting the soft start function ..................................................................................................... 94
12.2.4 Setting the starting voltage ........................................................................................................ 95
12.2.5 Setting the ramp time ................................................................................................................ 95
12.2.6 ON output .................................................................................................................................. 96
12.3 3RW30: LEDs and troubleshooting ........................................................................................... 97
12.4 Commissioning the 3RW40 ....................................................................................................... 98
12.4.1 Commissioning procedure ......................................................................................................... 99
12.4.2 Quick commissioning of the 3RW40 and optimization of the parameters ............................... 100
12.4.3 Setting the soft start function ................................................................................................... 101
12.4.4 Setting the starting voltage ...................................................................................................... 102
12.4.5 Setting the ramp time .............................................................................................................. 102
12.4.6 Current limiting in conjunction with a starting voltage ramp and ramp-up detection ............... 103
12.4.7 Setting the motor current ......................................................................................................... 103
12.4.8 Setting the current limiting value ............................................................................................. 104
12.4.9 Ramp-up detection .................................................................................................................. 104
12.5 Setting the soft stop function ................................................................................................... 105
12.5.1 Setting the ramp-down time ..................................................................................................... 105
12.6 Setting the motor protection function....................................................................................... 105
12.6.1 Setting the electronic motor overload protection ..................................................................... 106
12.6.2 Motor current settings .............................................................................................................. 107
12.6.3 Motor protection acc. to ATEX ................................................................................................. 107
12.7 Thermistor motor protection .................................................................................................... 108
12.8 Motor protection trip test.......................................................................................................... 108
12.9 Functions of the outputs .......................................................................................................... 109
12.9.1 Functions of the BYPASSED and ON / RUN outputs .............................................................. 109
12.9.2 Parameterizing the 3RW40 outputs .........................................................................................110
12.9.3 Function of the FAILURE / OVERLOAD output ....................................................................... 112
12.10 RESET MODE and functions of the RESET / TEST button .................................................... 113
12.10.1 SIRIUS 3RW40 2. to 3RW40 4. soft starters ........................................................................... 113

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SIRIUS 3RW30 / 3RW40
8Manual, 01/2010, 535 1995-02 DS01
12.10.2 SIRIUS 3RW40 5. to 3RW40 7. soft starters ........................................................................... 115
12.11 3RW40: LEDs and troubleshooting ......................................................................................... 117
13 Technical data ....................................................................................................................................... 121
13.1 3RW30..................................................................................................................................... 121
13.1.1 Overview .................................................................................................................................. 121
13.1.2 Selection and ordering data for standard applications and normal starting ............................. 122
13.1.3 3RW30..-.BB.. control electronics ............................................................................................ 123
13.1.4 3RW30..-.BB.. control times and parameters .......................................................................... 123
13.1.5 3RW30..-.BB.. power electronics ............................................................................................. 124
13.1.6 3RW30 13, 14, 16, 17, 18-.BB.. power electronics .................................................................. 124
13.1.7 3RW30 26, 27, 28-.BB.. power electronics .............................................................................. 125
13.1.8 3RW30 36, 37, 38, 46, 47-.BB.. power electronics .................................................................. 125
13.1.9 3RW30 main conductor cross-sections ................................................................................... 126
13.1.10 3RW30 auxiliary conductor cross-sections .............................................................................. 127
13.1.11 Electromagnetic compatibility according to EN 60947-4-2 ...................................................... 127
13.1.12 Recommended filters ............................................................................................................... 128
13.1.13 Types of coordination .............................................................................................................. 128
13.1.14 Fuseless version ...................................................................................................................... 129
13.1.15 Fused version (line protection only) ......................................................................................... 130
13.1.16 Fused version with SITOR 3NE1 fuses ................................................................................... 131
13.1.17 Fused version with SITOR 3NE3/4/8 fuses ............................................................................. 132
13.2 3RW40..................................................................................................................................... 134
13.2.1 Overview .................................................................................................................................. 134
13.2.2 Selection and ordering data for standard applications and normal starting (CLASS 10) ......... 135
13.2.3 Selection and ordering data for standard applications and normal starting (CLASS 10) (with
thermistor motor protection evaluation) ................................................................................... 137
13.2.4 Selection and ordering data for standard applications and normal starting (CLASS 10) ......... 139
13.2.5 Selection and ordering data for standard applications and heavy-duty starting (CLASS 20) .. 141
13.2.6 Selection and ordering data for standard applications and heavy-duty starting (CLASS 20) .. 143
13.2.7 3RW40 2., 3., 4. control electronics ......................................................................................... 145
13.2.8 3RW40 5., 7. control electronics .............................................................................................. 145
13.2.9 3RW40 2., 3., 4. control electronics ......................................................................................... 146
13.2.10 3RW40 5., 7. control electronics .............................................................................................. 146
13.2.11 3RW40 protection functions ..................................................................................................... 147
13.2.12 3RW40 control times and parameters ..................................................................................... 147
13.2.13 3RW40 2. to 7. power electronics ............................................................................................ 148
13.2.14 3RW40 24, 26, 27, 28 power electronics ................................................................................. 149
13.2.15 3RW40 36, 37, 38, 46, 47 power electronics ........................................................................... 150
13.2.16 3RW40 55, 56, 73, 74, 75, 76 power electronics ..................................................................... 151
13.2.17 3RW40 2., 3., 4. main conductor cross-sections ..................................................................... 152
13.2.18 3RW40 5., 7. main conductor cross-sections .......................................................................... 153
13.2.19 3RW40 .. auxiliary conductor cross-sections ........................................................................... 154
13.2.20 Electromagnetic compatibility according to EN 60947-4-2 ...................................................... 154
13.2.21 Recommended filters ............................................................................................................... 155
13.2.22 Types of coordination .............................................................................................................. 155
13.2.23 Fuseless version ...................................................................................................................... 156
13.2.24 Fused version (line protection only) ......................................................................................... 157
13.2.25 Fused version with SITOR 3NE1 fuses ................................................................................... 158
13.2.26 Fused version with SITOR 3NE3/4/8 fuses ............................................................................. 159
13.2.27 Motor protection tripping characteristics for 3RW40 (with symmetry) ..................................... 161

SIRIUS 3RW30 / 3RW40
Manual, 01/2010, 535 1995-02 DS01 9
Table of contents
13.2.28 Motor protection tripping characteristics for 3RW40 (with asymmetry) ................................... 161
13.3 Win-Soft Starter selection and simulation software ................................................................. 162
14 Dimension drawings ............................................................................................................................. 163
14.1 3RW30 for standard applications ............................................................................................ 163
14.2 3RW40 for standard applications ............................................................................................ 164
15 Typical circuit diagrams ....................................................................................................................... 167
15.1 Typical circuit for the optional thermistor motor protection evaluation..................................... 167
15.2 Control by pushbutton ............................................................................................................. 168
15.2.1 Control of the 3RW30 by pushbutton ...................................................................................... 168
15.2.2 Control of the 3RW40 by pushbutton ...................................................................................... 169
15.3 Control by switch ..................................................................................................................... 170
15.3.1 Control of the 3RW30 by switch .............................................................................................. 170
15.3.2 Control of the 3RW40 by switch .............................................................................................. 171
15.4 Control in automatic mode....................................................................................................... 172
15.4.1 Control of the 3RW30 in automatic mode ................................................................................ 172
15.4.2 Control of the 3RW40 in automatic mode ................................................................................ 173
15.5 Control by PLC ........................................................................................................................ 175
15.5.1 Control of the 3RW30 with 24 V DC by PLC ........................................................................... 175
15.5.2 Control of the 3RW40 by PLC ................................................................................................. 176
15.6 Control with an optional main / line contactor.......................................................................... 177
15.6.1 Control of the 3RW30 with a main contactor ........................................................................... 177
15.6.2 Control of the 3RW40 with a main contactor ........................................................................... 178
15.7 Reversing circuit ...................................................................................................................... 180
15.7.1 3RW30 reversing circuit .......................................................................................................... 180
15.7.2 3RW40 reversing circuit .......................................................................................................... 181
15.8 Control of a magnetic parking brake........................................................................................ 183
15.8.1 3RW30 motor with magnetic parking brake ............................................................................. 183
15.8.2 3RW40 2 to 3RW40 4, control of a motor with a magnetic parking brake ............................... 184
15.8.3 3RW40 5 to 3RW40 7, control of a motor with a magnetic parking brake ............................... 185
15.9 Emergency stop....................................................................................................................... 186
15.9.1 3RW30 emergency stop and 3TK2823 safety relay ................................................................ 186
15.9.2 3RW40 2 to 3RW40 4 emergency stop and 3TK2823 safety relay ......................................... 187
15.9.3 3RW40 5 to 3RW40 7 emergency stop and 3TK2823 safety relay ......................................... 189
15.10 3RW and contactor for emergency starting ............................................................................. 191
15.10.1 3RW30 and contactor for emergency starting ......................................................................... 191
15.10.2 3RW40 and contactor for emergency starting ......................................................................... 192
15.11 Dahlander / multispeed motor ................................................................................................. 194
15.11.1 3RW30 and Dahlander motor starting ..................................................................................... 194
15.11.2 3RW40 2 to 3RW40 4 and Dahlander motor starting .............................................................. 195
15.11.3 3RW40 5 to 3RW40 7 and Dahlander motor starting .............................................................. 197
16 Accessories ........................................................................................................................................... 199
16.1 Box terminal blocks for soft starters ........................................................................................ 199
16.2 Auxiliary conductor terminals................................................................................................... 199

Table of contents
SIRIUS 3RW30 / 3RW40
10 Manual, 01/2010, 535 1995-02 DS01
16.3 Covers for soft starters ............................................................................................................ 199
16.4 Modules for RESET................................................................................................................. 200
16.5 Link modules to 3RV10 motor starter protectors ..................................................................... 201
16.6 Link modules to 3RV20 motor starter protectors ..................................................................... 201
16.7 Optional fan to increase the switching frequency (3RW40 2. to 3RW40 4.)............................ 202
16.8 Spare parts for fans (3RW40 5., 3RW40 7.)............................................................................ 202
16.9 Operating instructions.............................................................................................................. 202
A Appendix ................................................................................................................................................ 203
A.1 Configuration data ................................................................................................................... 203
A.2 Table of parameters used........................................................................................................ 205
A.3 Correction sheet ...................................................................................................................... 206

SIRIUS 3RW30 / 3RW40
Manual 01/2010, 535 1995-02 DS01 11
1
Introduction
1.1 Important notes
Purpose of the manual
This manual contains fundamental information and practical tips for using SIRIUS soft
starters. The SIRIUS 3RW30 and 3RW40 soft starters are electronic motor control devices
that facilitate optimal starting and stopping three-phase induction motors.
The manual describes all of the functions of the SIRIUS 3RW30 and 3RW40 soft starters.
Target group
This manual is intended for any user involved in
• Commissioning
• Servicing and maintaining
• Planning and configuring systems
Basic knowledge required
A general knowledge of the field of electrical engineering is required to understand this
manual.
Scope of validity
The manual is valid for the SIRIUS 3RW30 and 3RW40 soft starters. It describes the
components that are valid at the time of publication. SIEMENS reserves the right to include a
Product Information for each new component, and for each component of a later version.
Standards and approvals
The SIRIUS 3RW30 and 3RW40 soft starters are based on the IEC/EN 60947-4-2 standard.
Disclaimer of liability
It is the responsibility of the manufacturer to ensure that a system or machine is functioning
properly as a whole. SIEMENS AG, its regional offices, and associated companies
(hereinafter referred to as "SIEMENS") cannot guarantee all the properties of a whole plant
system or machine that has not been designed by SIEMENS.
Similarly, SIEMENS can assume no liability for recommendations that appear or are implied
in the following description. No new guarantee, warranty, or liability claims beyond the scope
of the SIEMENS general terms of supply are to be derived or inferred from the following
description.

Introduction
1.1 Important notes
SIRIUS 3RW30 / 3RW40
12 Manual, 01/2010, 535 1995-02 DS01
Orientation aids
The manual contains various features supporting quick access to specific information:
• At the beginning of the manual you will find a table of contents.
• A comprehensive index at the end of the manual allows quick access to information on
specific subjects.
Continuously updated information
Your regional contact for low-voltage switchgear with communications capability will be happy
to help you with any queries you have regarding the soft starters. A list of contacts and the
latest version of the manual are available on the Internet at (www.siemens.com/softstarter):
For all technical queries, please contact:
Correction sheet
A correction sheet is included at the end of the manual. Please use it to record your
suggestions for improvements, additions, and corrections, and return the sheet to us. This will
help us to improve the next edition of the manual.
Technical Assistance: Phone: [phone] (8°° - 17°° CET) Fax: [phone]
e-mail: (mailto:[email protected])
Internet: (www.siemens.com/lowvoltage/technical-assistance)

DANGER
• Disconnect the system and all devices from the power supply before starting work.
• Secure against switching on again.
• Verify that the equipment is not live.
• Ground and short-circuit.
• Erect barriers around or cover adjacent live parts.
DANGER
SIRIUS 3RW30 / 3RW40
Manual 01/2010, 535 1995-02 DS01 13
2
Safety information
2.1 Before commencing work: Isolating the equipment from the supply
system and ensuring that it cannot be reconnected.
2.2 Five safety rules for work in or on electrical systems
A set of rules, which are summarized in DIN VDE 0105 as the "five safety rules", are defined
for work in or on electrical systems as a preventative measure against electrical accidents:
1. Isolate
2. Secure against switching on again
3. Verify that the equipment is not live
4. Ground and short-circuit
5. Erect barriers around or cover adjacent live parts
These five safety rules must be applied in the above order prior to starting work on an
electrical system. After completing the work, proceed in the reverse order.
It is assumed that every electrician is familiar with these rules.
Hazardous voltage Will cause death or serious injury.
Hazardous voltage Will cause death or serious injury.
Qualified Personnel.
The equipment / system may only be commissioned and operated by qualified personnel.
For the purpose of the safety information in these Operating Instructions, a "qualified person"
is someone who is authorized to energize, ground, and tag equipment, systems, and circuits
in accordance with established safety procedures.

Safety information
2.2 Five safety rules for work in or on electrical systems
SIRIUS 3RW30 / 3RW40
14 Manual, 01/2010, 535 1995-02 DS01
Explanations
1. The isolating distances between live and deenergized parts of the system must vary
according to the operating voltage that is applied.
"Isolate" refers to the all-pole disconnection of live parts.
All-pole disconnection can be achieved, e.g. by.:
- Switching off the miniature circuit breaker
- Switching off the motor circuit breaker
- Unscrewing fusible links
- Removing LV HRC fuses
2. The feeder must be secured against inadvertent restarting to ensure that it remains
isolated for the duration of the work. This can be achieved, for instance, by securing the
motor and miniature circuit breakers with lockable blocking elements in the disconnected
state, either using a lock or by unscrewing the fuses.
3. The deenergized state of the equipment should be verified using suitable test equipment,
e.g. a two-pole voltmeter. Single-pole test pins are not suitable for this purpose. The
absence of power must be established for all poles, phase to phase, and phase to N/PE.
4. Grounding and short-circuiting are only mandatory if the system has a nominal voltage
greater than 1 kV. In this case, the system should always be grounded first and then
connected to the live parts to be short-circuited.
5. These parts should be covered, or barriers erected around them, to avoid accidental
contact during the work with adjacent parts that are still live.

SIRIUS 3RW30 / 3RW40
Manual 01/2010, 535 1995-02 DS01 15
3
Product description
3.1 Fields of application
Soft starters are used to start three-phase induction motors with reduced torque and reduced
starting current.
SIRIUS soft starter family
The SIEMENS SIRIUS soft starter family comprises three different versions with different
functionalities and prices.
3RW30 and 3RW40
Simple or standard applications are covered by the SIRIUS 3RW30 and 3RW40 soft starters
and are described in this manual.
3RW44
The SIRIUS 3RW44 soft starter is used if higher functionality is specified, e.g. communication
over PROFIBUS or the availability of measuring and monitoring values, as well as for ultra-
heavy-duty starting. The SIRIUS 3RW44 soft starter is described in a separate system
manual.
Download from 3RW44 manual (http://support.automation.siemens.com/WW/
llisapi.dll?func=cslib.csinfo&lang=de&objid=21772518&caller=view).
3.2 Basic physical principles of a three-phase induction motor
SIRIUS soft starters are used to reduce the current and torque of a three-phase induction
motor during the startup process.
3.2.1 Three-phase induction motor
Fields of application
Three-phase induction motors are used in a wide range of applications in commerce, industry,
and trade owing to their simple, robust design and their minimal maintenance.
Problem
If a three-phase induction motor is started directly, its typical current and torque
characteristics can cause disturbances in the supply system and the load machine.

Product description
3.2 Basic physical principles of a three-phase induction motor
SIRIUS 3RW30 / 3RW40
16 Manual, 01/2010, 535 1995-02 DS01
Starting current
Three-phase induction motors have a high direct starting current Istarting. Depending on the
motor type, this current can be between three and fifteen times as high as the rated
operational current. Seven or eight times the motor's rated current can be assumed as a
typical value.
Disadvantage
This results in the following disadvantage:
• Higher load on the electrical supply system. The supply system must therefore be
dimensioned for this higher power during the motor startup.
Figure 3-1 Typical starting current characteristic of a three-phase induction motor
Starting torque
The starting torque and the breakdown torque can usually be assumed to be between two
and four times the rated torque. From the point of view of the load machine, this means that
the starting and acceleration forces exert a higher mechanical load on the machine and the
product being conveyed compared to nominal operation.
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Product description
3.3 Functional principle of the SIRIUS 3RW30 and 3RW40 soft
SIRIUS 3RW30 / 3RW40
Manual, 01/2010, 535 1995-02 DS01 17
Disadvantages
This results in the following disadvantages
• A higher load is placed on the machine's mechanical components
• The costs for replacing worn parts and maintaining the application are higher
Figure 3-2 Typical starting torque characteristic of a three-phase induction motor
Remedy
The SIRIUS 3RW30 and 3RW40 electronic soft starters allow the current and torque
characteristics during starting to be optimally adapted to the requirements of each application.
3.3 Functional principle of the SIRIUS 3RW30 and 3RW40 soft starters
The SIRIUS 3RW30 and 3RW40 soft starters have two antiparallel thyristors in two out of the
three phases. One thyristor for the positive half-wave and one for the negative half-wave is
provided in each phase (refer to Fig. "Phase angle control and schematic diagram of a two-
phase controlled soft starter with integral bypass contacts"). The current in the third,
uncontrolled phase is the sum of the currents in the controlled phases.
The rms value of the motor voltage is increased (from a settable starting voltage) to the rated
motor voltage within a definable ramp-up time by means of the phase angle control.
The motor current changes in proportion to the voltage applied to the motor. As a result, the
starting current is reduced by the factor of this voltage.
There is a quadratic relationship between the torque and the voltage applied to the motor. As
a result, the starting torque is reduced quadratically in relation to this voltage.
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Product description
3.3 Functional principle of the SIRIUS 3RW30 and 3RW40 soft starters
SIRIUS 3RW30 / 3RW40
18 Manual, 01/2010, 535 1995-02 DS01
Example
The diagrams below show the starting current and torque characteristics for a three-phase
induction motor in combination with a soft starter:
Figure 3-3 Reduced current characteristic of a three-phase induction motor during starting with a
SIRIUS 3RW30 or 3RW40 soft starter
SIEMENS 1LG4253AA motor (55 kW)
Rated data at 400 V
Pe: 55 kW
Ie: 100 A
Idirect starting: Approx. 700 A
Me:355 Nm ; e.g.: Me= 9.55 x 55 kW x
ne: 1480 rpm
Mdirect starting: Approx. 700 Nm
Set starting voltage: 50 % (½ of mains voltage)
=> Istarting ½ of direct starting current (approx. 350 A)
=> Mstarting ¼ of direct starting torque (approx. 175 Nm)
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Product description
3.3 Functional principle of the SIRIUS 3RW30 and 3RW40 soft
SIRIUS 3RW30 / 3RW40
Manual, 01/2010, 535 1995-02 DS01 19
Figure 3-4 Reduced torque characteristic of a three-phase induction motor during starting with a
SIRIUS 3RW30 or 3RW40 soft starter
Soft start /soft stop
This means that, since the motor voltage is controlled by the electronic soft starter during the
startup process, the consumed starting current and the starting torque generated in the motor
are also controlled.
The same principle is applied during the stop process. This ensures that the torque generated
in the motor is gradually reduced, so that the application can stop smoothly (the soft stop
function is only supported by the 3RW40).
The frequency remains constant during this process and corresponds to the mains frequency,
in contrast to frequency controlled starting and stopping of a frequency converter.
Bypass mode
Once the motor has been started up correctly, the thyristors are subject to fully advanced
control, meaning that the whole mains voltage is applied to the motor terminals. As the motor
voltage does not have to be controlled during operation, the thyristors are bridged by integral
bypass contacts that are rated for AC1 current. This minimizes the waste heat generated
during uninterrupted duty (which is caused by the thyristor's power loss), and minimizes
heating up of the switching device's environment.
The bypass contacts are protected by an integrated, electronic arc quenching system during
operation. If they are opened in the event of a fault, e.g. if the control voltage is temporarily
interrupted, mechanical vibrations occur, or the coil operating mechanism or the main contact
spring has reached the end of its service life and is defective, the equipment is not damaged.
The diagram below shows the method of operation of the SIRIUS 3RW30 and 3RW40 soft
starters:
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Product description
3.3 Functional principle of the SIRIUS 3RW30 and 3RW40 soft starters
SIRIUS 3RW30 / 3RW40
20 Manual, 01/2010, 535 1995-02 DS01
Figure 3-5 Phase angle control and schematic diagram of a two-phase controlled soft starter with integral bypass
contacts
3.3.1 Method of operation of a two-phase controlled soft starter
A special method of operation is used for the SIRIUS 3RW30 and 3RW40 two-phase
controlled soft starters based on SIEMENS' patented "polarity balancing" control principle.
Two-phase control
The SIRIUS 3RW30 and 3RW40 soft starters are two-phase controlled soft starters, in other
words they are designed with two antiparallel thyristors in each of phases L1 and L3. Phase 2
is an uncontrolled phase, which is merely guided through the starter by a copper connection.
In a two-phase controlled soft starter, the current that results from the superimposition of the
two controlled phases flows in the uncontrolled phase. The main advantages of two-phase
control include the more compact size compared to a three-phase version and the lower
hardware costs.
The occurrence of DC components, caused by the phase angle and the overlapping phase
currents, is a negative physical effect of two-phase control during the startup process that can
mean a louder noise is produced by the motor. The "polarity balancing" control principle was
developed and patented by SIEMENS to prevent these DC components during starting.
Figure 3-6 Current characteristic and occurrence of DC components in the three phases without "polarity
balancing"
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