SK4403 - Variable speed drive - CONTROL TECHNIQUES

Control Techniques SK4403 frequency inverter, Commander SK

The SK4403 frequency inverter is part of the Commander SK series from Control Techniques (Nidec). Designed for reliable control of three-phase induction motors in industrial environments, it meets common speed variation requirements on production lines, utilities and process machines. Its architecture includes two microprocessors, including a DSP dedicated to PWM generation, enabling precise modulation of voltage and frequency for stable drive performance, reduced electrical noise and optimized efficiency. Powered by three-phase 380 to 480 V AC, the model offers a rated power of 45 kW (≈ 60 HP) with a nominal output current of approximately 96 A. Control can be configured in open-loop vector mode or scalar V/Hz depending on process needs. The range is characterised by streamlined commissioning, built-in protection functions and parameterisation via local keypad or manufacturer's software tools to secure maintenance and reduce downtime.

Technical specifications

• Manufacturer reference : SK4403
• Range : Commander SK
• Manufacturer : Control Techniques (Nidec)
• Type : Variable speed drive for three-phase induction motors
• Supply voltage : 380 to 480 V AC three-phase
• Rated power : 45 kW (≈ 60 HP)
• Nominal output current : approximately 96 A
• Output voltage : 0 to 480 V three-phase
• Control mode : Open-loop vector and scalar V/Hz
• PWM switching : Carrier frequency adjustable and driven by DSP
• Thermal management : Cooling fan controlled by internal temperature
• Application functions : Acceleration and deceleration ramps, configurable minimum and maximum speeds, overload and mains-fault protections, motor protection functions

Overview of the Commander SK range

The Commander SK series is a proven variable frequency drive platform, widely deployed for speed control of induction motors. It targets easy commissioning, robustness in industrial environments and functional versatility for conveying, pumping, ventilation and general machine applications. Integration is typically performed in an electrical cabinet, with direct access to the programming keypad for adjusting setpoints and ramps, as well as dedicated software tools for parameter duplication and preventive maintenance. The open-loop vector control logic improves low-speed torque control compared with V/Hz alone, while maintaining a fast configuration.

• DSP-optimised control : PWM generation finely manages voltage and frequency, which stabilises speed, limits harmonics and helps reduce the audible noise of the motor.
• Built-in protection functions : diagnostics, overload thresholds, mains-fault handling and motor thermal protections contribute to securing the installation and preserving equipment.

The SK4403 fits into this framework as a 45 kW drive intended for standard industrial requirements where continuity of service, energy control and operational ease are essential. It meets the needs of many utilities and production lines without excessive complexity, which eases maintenance and staff training.

Industrial applications

This Control Techniques frequency inverter adapts to a wide range of processes. Its configuration in vector or V/Hz provides the flexibility needed to stabilise speed, smooth starts and finely tune setpoints, while reducing mechanical wear caused by jolts. Typical use cases include flow management, pressure maintenance, conveyor speed regulation and coordination of distributed drives. It can be paired with a programmable logic controller and process sensors to form a robust and reliable control loop.

• Conveying and material handling : control of drive motors for belts, rollers and transfers with configurable ramps to limit mechanical shocks.
• Pumping and HVAC : speed adjustment for flow and pressure control, promoting energy efficiency and reducing inrush current at start-up.
• Industrial ventilation : speed regulation for fans used in extraction, filtration and process cooling.
• Compression : control of compressor speed to stabilise pressure and reduce start-stop cycles.
• Process machines : dosing, mixing, auxiliary drives in continuous production with precise setpoint adjustment.

Integration and communication

The SK4403 easily integrates into an existing automation architecture. Speed references can be provided via analog inputs, preset setpoints or digital commands, while safety and protection functions reduce the risk of major faults. The local interface provides quick access to essential parameters, ramp settings and speed limits, facilitating start-up and first-level on-site maintenance.

Communication with a PLC can be achieved using standard I/Os, and the addition of optional modules depends on the range configuration and available versions. Configuration is performed via the local keypad for routine adjustments, or with the manufacturer's software tool for saving, duplicating and documenting configurations. This approach supports standardisation of workshop settings and reduces intervention times. The drive coexists easily with numerical control systems and servo drives on mixed installations where each technology is dedicated to its functional scope.

Availability and warranty

The Control Techniques SK4403 frequency inverter is offered by Standard Exchange Industry as refurbished supply, exchange unit or repair. Each unit is bench-tested according to strict procedures and delivered with a warranty whose duration depends on the chosen service. Shipping is ensured within 24 to 72 hours to address urgent line stoppages. Our technical team supports you to confirm electrical and functional compatibility, validate rated values, determine key commissioning parameters and secure the replacement in your cabinet. If in doubt, we analyse the motor nameplate, load constraints and the expected control mode to guide you to the correct reference within the Commander SK range and optimise the restart of your installation.