VKS8000
Candidate with built-in bypass and advanced start/stop options; selection is based on motor FLA and starting duty, not motor kW alone.
Open technical pageHigh-performance soft starter
Siemens SIRIUS 3RW55 and Veikong VKS8000: soft-starter selection guide
Compare 3RW55 and VKS8000 by motor FLA, starting duty, bypass, torque/adaptive control, motor protection, communications and event logging.
Short answer
What does this page recommend?
A technical alternative, not a drop-in substitute
VKS8000 is an advanced start/stop candidate for pumps, fans, compressors or conveyors, but a 3RW55 selection cannot be converted by motor kW alone. Motor FLA, load torque/inertia, starting time and starts per hour are recalculated.
Veikong
ProControl products to evaluate first
The exact configuration is selected after engineering review.
VKS6000
More basic soft-starter family; current, duty cycle, bypass architecture and protection scope are verified before design.
Open technical pageTechnical comparison
Similar requirement, different architecture
The table explains product architectures; it is not an exact order-code selection.
| Validation area | Siemens SIRIUS 3RW55 | Veikong / ProControl candidate |
|---|---|---|
| Selection basis | 3RW55 selection uses motor rated current, load class, starting current/time and repetition count. | The VKS8000 model table is selected against the same FLA and starting duty; VKS6000 is assessed separately only for more basic functional needs. |
| Bypass topology | 3RW55 internal bypass architecture, thermal duty and connection method depend on exact-device documentation. | VKS8000 is published with built-in bypass; contactor current, bypass transition, fault behaviour and heat loss are tested. |
| Start/stop mode | Siemens 3RW55 offers torque control and advanced methods for difficult starts. | VKS8000 voltage, current-limit, torque and adaptive-start options are tuned on the load; identical names do not mean identical algorithms. |
| Motor protection | 3RW55 uses a motor thermal model and sensor-based protection according to configuration. | VKS8000 is assessed for over/undercurrent, stall, phase and temperature protection; exact PTC/PT100 input wiring is verified. |
| Communications and HMI | 3RW55 can integrate into Siemens automation using PROFINET and other communication modules. | VKS8000 connects through Modbus and published communications options; PROFINET requires evidence for the official card/device file. |
| Logging and maintenance | 3RW55 diagnostics, events and parameter management are handled with Siemens tools. | VKS8000 LCD, event log and parameter upload/download are tested in the maintenance scenario; historical data format is not transferred. |
Suitable scenario
When is it worth evaluating?
- Pumps, fans and compressors with long starts
- Current-limit and controlled-stop retrofits on conveyors or crushers
- New panels requiring Modbus monitoring and built-in bypass
Migration gate
Before making a decision
- Record motor FLA, service factor, connection and insulation class.
- Calculate load-torque curve, inertia, required starting time and starts per hour.
- Document 3RW55 bypass, inside-delta, sensor and communications use.
- Verify VKS8000 exact current/voltage code plus thermal and protection settings.
- Run cold/hot motor starts, stall, phase-loss and emergency-stop tests under load.
Frequently asked
Clear answers about alternatives and migration
Is this a drop-in replacement?
No. It is not a direct substitute until exact model, electrical, protocol-role, mechanical, software and certification checks pass.
What should I provide for selection?
The exact existing code, diagram or I/O list, PLC/network data, supply, environment and special functions in use.
Is the same motor kW rating enough to select a VKS8000 model?
No. Motor FLA, mains voltage, load torque, starting time/current, starts per hour, ambient conditions and bypass duty must be calculated together.
Official manufacturer sources: Siemens SIRIUS 3RW soft starter official page · Siemens official Industrial Controls catalogue hub · Veikong VKS8000 official product page · Veikong VKS8000 official catalogue · Veikong VKS6000 official product page
This content compares manufacturer-published data under the same project requirement; it does not guarantee direct substitution or project compatibility. ProControl engineering must validate exact model, revision, protocol, electrical, safety and environmental conditions.
Validate the match with an engineer
Share the exact existing code, I/O list, network and environment so we can identify the right solution without assumptions.