Siemens 3RW4443-6BC44 Soft Starter

MLFB Order Code Breakdown

3RW 44 43 6 B C 4 4

1. 3RW: SIRIUS soft starter product series
2. 44: High-performance built-in bypass 3-phase fully controlled soft starter (independent thyristor regulation per phase, integrated bypass contactor as standard)
3. 43: Size code, rated current 203 A at 40 °C for standard loads
4. 6: Control circuit terminal type = screw terminals; main circuit connected via copper busbars
5. B: Integrated bypass contactor (2/3-phase bypass for zero loss during steady-state operation)
6. C: Independent 3-phase thyristor control (full 3-phase control to balance 3-phase currents)
7. 4: Control supply voltage Us = AC 230 V
8. 4: Main circuit operating voltage Ue = AC 200～460 V
9. Core Electrical Parameters (40 °C, Class 10 Standard Load)

III. Load Matching & Selection Limits

1. Applicable Loads

Water pumps, fans, belt conveyors, air compressors, chillers, centrifugal equipment (fixed speed, only smooth start/stop required)

2. Derating Reference for Heavy-Duty Operation (40 °C)

Class 20 heavy duty (frequent starts, high starting torque): permissible current 170 A, matched motor 90 kW

Class 30 extra heavy duty (ball mills, crushers): permissible current 145 A, matched motor 75 kW

3. Prohibited Operating Conditions

Continuous speed regulation, frequent forward/reverse switching, high-frequency jogging (≥30 times per hour)

1. Hardware Structure & Wiring Description
2. Main Circuit: Copper busbar terminals; L1/L2/L3 line side input, T1/T2/T3 motor side output; supports standard wiring and inside-delta wiring
3. Control Circuit: Screw terminals for start/stop signals, fault outputs, reset, external thermistor input
4. Operator Panel: Built-in LCD display for setting start ramp, initial voltage, soft stop, current limit and protection thresholds
5. Installation: Vertical wall mounting; minimum 150 mm top/bottom clearance for heat dissipation; ambient temperature 0～40 °C (derate for temperatures above 40 °C)
6. Product Lifecycle & Replacement Models
7. Status: 3RW44 series discontinued (PLM: PM490 end-of-support phase); original manufacturer stops mass production, only stock spare parts available
8. Direct OEM Replacement Model (Recommended for New Projects)

3RW5543-6HA14 (new-generation 3RW55 series, same 203 A rated current, 230 V control supply, 200-460 V main voltage, screw terminals, integrated bypass)

3. Differences Between Old & New Models

Smaller footprint, lower power consumption, native Modbus RTU and optimized protection logic for 3RW55

Different mounting cutout dimensions; copper busbars and mounting brackets need modification during cabinet retrofit

1. Recommended Matching Protection Devices
2. Main Circuit Short-Circuit Protection: Moulded case circuit breaker matched to 110 kW motor circuit
3. Specialized Thyristor Protection: aM/gR ultra-fast fuse 500 V 315 A (mandatory upstream of soft starter, no thyristor short-circuit protection without it)
4. Additional Motor Protection: External PTC thermistor connectable to control terminals for winding overtrip protection

VII. Typical Troubleshooting Matrix

VIII. Key Advantages

1. Independent 3-phase voltage regulation; eliminates 3-phase current unbalance common in 2-phase soft starters, extending motor bearing service life
2. Integrated bypass eliminates thyristor power loss during steady operation, delivering over 98% energy saving vs non-bypass models
3. Supports soft stop and pump stop water hammer suppression, ideal for water supply, drainage and HVAC systems
4. Comprehensive integrated motor protection, eliminating the need for separate thermal overload relays

Full Dimension Specifications of Siemens 3RW4443-6BC44

1. Overall Equipment Dimensions (W × H × D, Unit: mm)

210 (Width) × 230 (Height) × 298 (Depth)

1. Mounting Cutout & Fixing Dimensions
2. Horizontal center distance between mounting holes: 167 mm
3. Vertical center distance between mounting holes: 190 mm
4. Fastener specification: M8 bolt, tightening torque 15 N·m
5. Cabinet panel cutout minimum reserved width ≥210 mm, height ≥230 mm

III. Mandatory Minimum Cabinet Clearance for Heat Dissipation (Vertical Wall Mount)

Top clearance: ≥100 mm

Bottom clearance: ≥75 mm

Side clearance (multiple units side-by-side): ≥5 mm

Equipment rear surface to cabinet backplate: direct contact permitted

1. Outer Carton Dimensions (Warehousing & Logistics Reference)

348 × 433 × 394 mm, net weight 11.22 kg

1. Supplementary Notes
2. Protection class: IP00; for cabinet installation only
3. All 3RW4443 variants (-6BC34/-6BC44/-2BC45) share identical overall dimensions; differences only in control terminals and supply voltage
4. Replacement model 3RW5543-6HA14 has a smaller footprint; recalculate cabinet cutout size for retrofits

Complete List & Function Definition of Control Terminals – Siemens 3RW4443-6BC44

This model is equipped with screw-type control terminals, categorized into five groups: control power supply, digital inputs, motor PTC temperature sensing, programmable relay outputs, general fault relay.

1. Control Power Supply Terminals (Unit Main Supply)
2. A1, A2

Function: Main control power supply for soft starter

Model rating: AC 230 V ±10%, 50/60 Hz

Wiring rule: A1 live line L, A2 neutral line N

2. PE

Control circuit protective earth terminal; connect to cabinet earth busbar

3. L+, L-

Built-in internal DC24 V auxiliary supply for passive digital input switches; external 24 V power supply not required

L+ = DC24 V positive pole; L= DC24 V negative pole (common ground)

1. 4 Programmable Digital Input Terminals IN1 / IN2 / IN3 / IN4

Logic: Connect one end of switch to L+, the other end to corresponding INx to trigger assigned function; all functions configurable via panel parameters

Factory Default Allocation

IN1: Motor start (Parameter Group 1 forward rotation)

IN2: Unassigned

IN3: Unassigned

IN4: Fault trip reset

All Customizable Functions

Local manual mode, emergency start, low-speed creep, fast emergency stop, fault reset, 3 groups of forward/reverse motor parameter switching

III. Motor Winding Temperature Sensing Terminals T1, T2

For external motor PTC thermistor connection (motor overheat protection)

Soft starter trips automatically when winding temperature exceeds threshold

Short-circuit T1 and T2 if no PTC fitted to disable thermal protection

1. 3 Independent Programmable Relay Outputs (Passive dry contacts, AC250 V / 5 A)

Each pair consists of normally-open contacts with fully assignable functions via parameter menu

1. 13, 14 Output 1

Default: Motor running signal (closes after startup completion and bypass contactor pull-in)

2. 23, 24 Output 2

Default: Unassigned; configurable for bypass status, startup-in-progress, pre-alarm, DC braking, etc.

3. 33, 34 Output 3

Default: Unassigned; customizable for all types of equipment status signals

1. General Fault Relay Terminals 95, 96, 98 (Global Fault Alarm)

3-pole changeover contact for unified fault signaling, widely used in safety circuits

95: Common terminal COM

95-96: Normally Closed (NC): conductive when unit healthy; opens upon fault trip

95-98: Normally Open (NO): closes when fault occurs, for fault indicator light / alarm horn wiring

Terminal Summary Table

Supplementary Wiring Guidelines

1. Tightening torque for control wires: 1.2~1.5 N·m; wire cross-section 0.75~1.5 mm² copper conductors
2. Digital inputs are passive contact type; power solely from internal L+/Lwithout external PLC 24 V supply
3. Series the normally closed 95/96 contacts in safety circuit to cut upstream contactor power on fault
4. Profibus communication requires separate 3RW4900-0KC00 module with dedicated port (not part of front control terminals)