Siemens 3RW4435-6BC45 Soft Starter

Order Number Coding Breakdown

3RW4435-6BC45

1. 3RW: Сименс SIRIUS soft starter series
2. 44: High-end heavy-duty full-function model (3-phase thyristors, integrated bypass, Сорт 30 heavy overload support, PTC thermistor protection, soft braking, inside-delta connection compatible)
3. 35: Код размера, rated operating current 134A
4. 6: Screw terminals for control circuit (2 = spring cage terminals); main circuit connected via copper busbars
5. BC: Core function definition

B = Integrated bypass contactor (short-circuits thyristors during operation to reduce heat loss)

C = Full 3-phase controlled thyristors (higher starting torque and balanced current compared to 2-phase BB versions)

6. 45: Control supply voltage AC 230V (44 = AC 110V, 46 = AC/DC 24V)
7. Core Electrical Rated Parameters (40°C Ambient, Сорт 10 Standard Load)
8. Номинальный ток & Matching Motor Power

2. Схема управления

Control supply: AC 230V ±10% (defined by suffix 45)

Control terminals: Screw fastening; Standard digital start/stop, fault relay, running feedback, PTC thermistor input

3. Physical Data & Масса

Вес нетто: 7.9кг

Монтаж: Vertical wall-mounted; Класс защиты IP20 (for cabinet internal installation)

Степень загрязнения 3, соответствует МЭК 60947-4-2

III. Standard Built-In Core Functions (Exclusive to High-End 3RW44 Series)

1. Integrated Bypass Contactor

Automatically short-circuits thyristors after motor startup to drastically reduce heat generation, enabling long-duration continuous operation without external bypass equipment.

2. Multi-Stage Start/Stop Modes

Dual voltage ramp soft start (initial voltage and ramp-up time independently adjustable)

Пуск с ограничением тока (suppresses inrush current, ideal for sites with limited grid capacity)

Adjustable soft stop; DC braking function (eliminates water hammer during inertial shutdown of fans and water pumps)

3. Stepwise Overload Protection

Supports Class 10/10A/20/30 trip curves:

Сорт 10: Стандартные вентиляторы, водяные насосы

Сорт 20: Тяжелые конвейеры, миксеры

Сорт 30: Extra-heavy-duty crushers, шаровые мельницы, воздушные компрессоры

4. Motor PTC Thermistor Protection

Directly connects to embedded motor temperature sensors; immediate shutdown upon overtemperature to cover blind spots of current-only protection.

5. Inside-Delta Connection Support

The soft starter is installed between star-delta motor terminals, capable of driving motors with nearly double power under the same frame size, greatly reducing cabinet footprint and procurement costs.

6. Comprehensive Fault Diagnostics: Phase loss, thyristor short circuit, перегрев, перегрузка двигателя, PTC overtemperature, start timeout; passive relay fault output.
7. Load Selection Limits (Startup Frequency Restrictions, 40°С)

1. Типичные сценарии применения
2. Водоснабжение & Дренаж: High-power centrifugal pumps, circulating water pumps (soft braking eliminates water hammer)
3. ОВК: Large centrifugal fans, вытяжные вентиляторы
4. Горное дело & Строительные материалы: Ball mills, дробилки, heavy-duty belt conveyors
5. Air Compressor Stations: Screw/piston air compressors, чиллеры
6. Химическая промышленность: Heavy-duty motors for mixing and extruders
7. Информация о поэтапном отказе & Direct Replacement Model
8. Product Status: The entire 3RW44 series is gradually phased out; Siemens’ new upgraded generation is the 3RW55 series
9. Perfect drop-in replacement with identical specifications: 3RW5535-6HA14

Identical AC230V control supply, винтовые клеммы, integrated bypass, 134Номинальный ток

Full functional coverage of 3RW44 plus optional communication interfaces (Modbus/Profinet), more compact dimensions and optimized heat dissipation

3. Примечания по замене: Control terminal definitions are largely compatible; ramp and current limit parameters can be reused directly. Cabinet mounting cutouts match, requiring no modification to internal copper busbars.

VII. Operation Prohibitions & Ключевые моменты установки

1. Derating is mandatory for ambient temperatures above 40°C; только 75% rated current is allowed at 60°C. Derating is also required for altitudes above 1000m.
2. Upside-down vertical or horizontal flat mounting is forbidden; upper and lower heat dissipation air ducts must remain unobstructed.
3. A cabinet cooling fan is recommended for Class 30 heavy-duty operation to avoid overheating faults.
4. Inside-delta connection requires 6-wire motors and cannot be used with standard 3-wire motors.
5. Torque for tightening main circuit copper busbar bolts must strictly follow the manual to prevent terminal burnout from overheating.
6. The AC230V control supply must not be mistakenly connected to 380V, otherwise the control board will burn out instantly.

VIII. Differentiation of Derivative Models with Identical Frame Size (Only Suffix/Terminal Differences)

Classification of Complete Control Modes for Siemens 3RW4435-6BC45 Soft Starter

Three major external control methods are available: Local HMI panel control, hardwired digital terminal control, and fieldbus remote control. Тем временем, 6 built-in motor start-stop process control modes are integrated, explained separately below.

1. External Command Control Modes (Send Start/Reset/Mode Switch Commands)
2. Local Control via Onboard Panel (On-Site Operation)

The front panel is equipped with an LCD screen and 4 function keys for direct on-site operation without external wiring:

Функции: Local start, local stop, fault reset, parameter modification, switching between 3 motor parameter sets, real-time monitoring of operating current and fault codes

Приложения: On-cabinet commissioning, manual single-machine startup/shutdown, maintenance mode

Access Permission: Local/remote switch can be configured via terminals or bus communication; panel and remote control are interlocked, with only one control source active at a time.

2. Hardwired Digital Input Terminal Control (Самый распространенный, for PLC/Button Relays)

Secondary control terminals: Л+ (24VDC common positive), 4 programmable digital inputs IN1/IN2/IN3/IN4 with screw terminals (standard for model 6BC45) for freely assignable functions:

Factory Default Terminal Assignment

IN1: Forward start (Parameter Set 1)

IN2: Reverse start (Parameter Set 1)

IN3: Low-speed mode

IN4: Fault reset

Customizable Terminal Functions (Configurable as Required)

Local manual mode, emergency start, quick stop, switching of 3 independent motor parameter sets, аварийная остановка, interlock reset triggered by external faults, и т. д..

Typical Wiring Scenarios

1. Cabinet-mounted start/stop pushbuttons: IN1 connected to normally-open start contact, IN4 connected to reset contact
2. PLC digital output control: PLC DO channels drive IN1/IN2 for startup and shutdown
3. Multi-motor switching: IN1~IN4 toggle 3 distinct motor startup curves
4. On-site emergency stop and interlocked shutdown via external thermal relays
5. PROFIBUS-DP Fieldbus Remote Control (Optional Communication Module Required)

A PROFIBUS communication card can be fitted to the 3RW44 series for remote control via Siemens PLCs (S7-200 SMART/1200/1500/300/400):

1. Remote Commands: Начинать, останавливаться, reset and parameter set switching transmitted via bus
2. Data Exchange: Real-time upload of operating current, equipment status, fault codes and load percentage
3. Process Adaptation: Centralized upper computer monitoring of multiple soft starters, DCS system interlocking, unattended pump houses and fan rooms
4. Priority Setting: Permission switching between bus control and local terminals/panel; remote control automatically takes priority.

> Дополнительное примечание: The 3RW44 series has no native Profinet interface; the upgraded replacement 3RW55 series supports Profinet. Only DP communication is optional for the 3RW44 series.

1. Built-In Motor Start-Stop Process Control Modes (Motor Voltage Regulation Algorithms, Core Operation Logic)

Selectable via panel, terminals or bus communication to match diverse loads including pumps, фанаты, crushers and conveyors; 4 standard start modes plus 3 stop modes are integrated:

(1) Four Soft Start Control Modes

1. Voltage Ramp Start (Standard Mode for Fans & Насосы)

Linear voltage rise from a preset initial voltage to rated voltage for smooth torque build-up without current spikes; ramp time adjustable from 0.1 к 60 секунды.

2. Current-Limited Start (For Sites with Insufficient Grid Capacity)

Maximum inrush startup current is capped (adjustable between 150%~600% Ie) во избежание перегрузки сети, suitable for simultaneous startup of multiple motors or undersized transformers.

3. Kick Voltage Start (High Static Friction Loads: Screw Conveyors, Crushers, Ball Mills)

Short-duration high voltage output at startup instantaneously breaks static friction, then switches to ramp current limiting to prevent failed startup due to locked rotor.

4. Dual-Ramp Start (Heavy-Duty Air Compressors, Centrifuges)

Two-stage voltage rise curve: slow ramp at low speed followed by fast ramp at high speed, balancing low inrush and fast acceleration.

(2) Three Stop Control Modes

1. Soft Stop (Voltage Ramp Stop, Standard for Pumps to Prevent Water Hammer)

Voltage decreases gradually for smooth motor deceleration, eliminating pipeline water hammer and inertial fan impact; stop time adjustable from 0.1 к 60 секунды.

2. DC Braking Stop (Фанаты & High-Inertia Loads)

DC current injected into stator after cutting off 3-phase AC supply for rapid braking to shorten coasting time; DC braking is disabled for inside-delta connection.

3. Coasting Stop

Thyristor output cut off directly; motor freewheels to rest by inertia, applicable to general conveyors with no shock control requirements.

III. Auxiliary Supporting Control Functions

1. 3 Independent Motor Parameter Set Switching Control

IN1~IN4 terminals or fieldbus switch 3 complete sets of motor parameters (номинальный ток, ramp time, current limit value, класс поездки), enabling one soft starter to serve alternating motors of different power ratings.

2. PTC Motor Thermistor Temperature Control

Embedded motor temperature sensors connected to terminals T1/T2 trigger automatic shutdown on overtemperature, forming closed-loop temperature protection.

3. Stepwise Overload Protection Control

Four trip curves Class10/10A/20/30 with software closed-loop current monitoring for automatic tripping under overload conditions.

4. Automatic Bypass Control (Model Equipped with BC Integrated Bypass Contactor)

Bypass contactor closes automatically once startup completes and rated speed is reached to deactivate thyristors; the bypass opens automatically upon fault or stop command.

1. Сравнение & Selection Guide for the Three External Control Methods

Supplementary Model-Specific Explanations (3RW4435-6BC45)

1. BC stands for full 3-phase controlled thyristors with independent 3-phase voltage regulation, delivering superior torque balance compared to 2-phase BB variants.
2. Control supply AC230V; terminal L+ outputs 24VDC to directly drive passive on-site pushbuttons without auxiliary power supplies.
3. Three passive relay feedback outputs (Бег, Bypass Closed, General Fault) available for connection to indicator lamps and alarm circuits.

Six Official Standard Start-Stop Process Modes for Siemens 3RW4435-6BC45 (Combination of 4 Start Modes + 2 Main Stop Logic Types; 6 Complete Process Combinations Defined in Official Manual)

1. Four Standard Start Control Modes (Core Voltage Regulation Algorithms)
2. Voltage Ramp Start (Factory Default)

Basic linear voltage ramp logic with uniform rise from preset initial voltage to rated voltage without harsh current surges; ramp time adjustable 0.1~60s.

Приложения: Centrifugal pumps, standard centrifugal fans, light-duty conveyors; sites with sufficient grid capacity and no kick start demand.

Optional auxiliary Kick Start Pulse: Short-duration output of approx. 80% rated voltage prior to startup to overcome static friction for lightly seized loads.

2. Voltage Ramp + Current Limiting Start

Maximum startup current locked throughout the entire voltage ramp phase (adjustable 150%~600% Ie) to balance smooth acceleration and grid protection.

Приложения: Undersized transformers, simultaneous multi-motor startup, factory sites sensitive to grid voltage drop.

3. Torque Ramp Start

Linear regulation of motor output torque (instead of pure voltage adjustment) for smooth torque curves, minimal startup jitter and precise torque control.

Приложения: Precision conveyors, центрифуги, mixing equipment, loads with strict anti-vibration startup requirements.

4. Torque Ramp + Current Limiting Start

Closed-loop torque control paired with full-range dual current limitation to prevent locked rotor and suppress inrush current under heavy-duty operation.

Приложения: Class20/30 extra-heavy-duty equipment including ball mills, дробилки, heavy screw conveyors and air compressors.

Two Supplementary Special Start Modes (Independent Menu Selections, Not Used for Standard Processes)

1) Прямой онлайн (DOL) Full-Voltage Start: Thyristors fully conductive to replicate direct contactor startup, only for maintenance testing.

2) Motor Heating Mode: Continuous low-frequency low-voltage micro-current output for anti-freezing and moisture prevention of idle motors in cold winter; no load startup capability.

1. Matching Stop Control Modes (3 Stop Algorithms, Freely Combinable with Any of the 4 Start Modes to Form 6 Complete Start-Stop Processes)

Stop Mode Classification

1. Coasting Stop

Thyristor output cut off; motor freewheels to rest by inertia with zero braking torque.

Matching Loads: General belt conveyors with no shock mitigation requirements.

2. Torque Soft Stop / Pump Stop

Gradually declining voltage/torque output after stop command for slow deceleration; pump stop mode features optimized dedicated curves exclusively designed to eliminate pipeline water hammer.

Matching Loads: Water supply & drainage pumps, большие поклонники, prevents water hammer and material spillage.

3. DC Braking Stop / Combined Braking

3-phase AC supply disconnected; DC current injected into stator windings to generate braking magnetic field for fast halting of high-inertia loads; DC braking is unavailable for inside-delta connection.

Matching Loads: Exhaust fans, large centrifugal units to shorten coasting duration.

III. Six Complete Start-Stop Process Combinations Defined in Official Manual (Industry-Wide Term: Six Start-Stop Process Modes)

1. Voltage Ramp Start + Coasting Stop

Universal standard process for light-duty fans and general conveying equipment.

2. Voltage Ramp Start + Pump Soft Stop

Standard factory preset process for centrifugal water pumps to eliminate water hammer.

3. Voltage Ramp + Current-Limited Start + Coasting Stop

For medium/small fans and pumps installed at sites with insufficient grid capacity.

4. Torque Ramp Start + Torque Soft Stop

Low-vibration start and stop for precision conveyors, mixing equipment and centrifuges.

5. Torque Ramp + Current-Limited Start + Coasting Stop

For heavy-duty crushers, ball mills and screw air compressors.

6. Torque Ramp Start + DC Braking Stop

Fast braking process for high-inertia exhaust fans and centrifugal units.

1. Adjustable Key Parameters for Each Mode
2. Voltage Ramp: Initial voltage, ramp-up time, kick start voltage/kick duration
3. Current Limiting Mode: Maximum startup current percentage
4. Torque Control Mode: Initial startup torque, final torque, acceleration duration
5. Soft Stop: Deceleration time, minimum stop torque
6. DC Braking: Braking current, braking duration
7. Key Operation Restrictions
8. DC braking only supports standard 3-wire external motor connection and cannot be activated for 6-wire inside-delta motor wiring.
9. Kick start pulse cannot be enabled for extended periods; limited to 0~1s short output to avoid grid impact.
10. Torque ramp + current-limited start is the preferred selection for Class30 extra-heavy-duty loads to reduce locked rotor fault probability.