SK3403 - Variable speed drive - CONTROL TECHNIQUES

Control Techniques SK3403 Frequency Inverter - COMMANDER SK

The reference frequency inverter SK3403 belongs to the COMMANDER SK series from Control Techniques. Designed to control three-phase induction motors in general industrial applications, it operates on a 380-480 V AC three-phase supply and delivers approximately 22 kW (around 30 HP) with a nominal current of about 46 A. The platform includes two microprocessors, one being a DSP dedicated to real-time processing and PWM synthesis with adjustable carrier frequency. This architecture ensures precise speed control and stable open-loop torque response, with extensive configuration of min/max speeds, acceleration and deceleration ramps and protection thresholds. The cooling system features a fan controlled by heatsink temperature and internal thermal modelling to optimise dissipation, limit contamination and preserve component life. Intended for production environments, this drive meets the variable-speed needs of pumps, fans, conveyors and process equipment, with fast commissioning and easy integration with programmable logic controllers and numerical controllers via standard I/Os or optional modules depending on configuration.

Technical specifications

• Manufacturer reference : SK3403, clear identification for maintenance, spares and technical documentation
• Range : COMMANDER SK, AC drives for general industrial applications with extensive configuration options
• Manufacturer : Control Techniques, specialist in electrical drives for automation and industrial maintenance
• Type : Compact AC variable speed drive for induction motors, cabinet mounting and standard wiring
• Supply voltage : 380-480 V AC three-phase, 50/60 Hz, compatible with international industrial networks
• Rated power : approximately 22 kW, approximate equivalent 30 HP, sized for pump, ventilation and conveyor drives
• Rated output current : approximately 46 A, consistent with the power rating and thermal design of the unit
• Output voltage : three-phase AC synthesised by PWM, from 0 V to a value proportional to the supply voltage, suitable for the motor
• Control mode : open-loop asynchronous control with PWM, speed and torque settings tailored to the application
• Switching frequency : adjustable via application parameter, trade-off between EMI, efficiency and heating
• Cooling and thermal protection : fan controlled by heatsink temperature and internal thermal modelling for increased reliability

Overview of the COMMANDER SK range

The COMMANDER SK series covers speed control of induction motors in industrial and commercial installations where ease of implementation, robustness and consistent performance are priorities. The digital architecture with DSP ensures clean PWM modulation, repeatable response to setpoints and easy adaptation to varying loads. The drive offers comprehensive configuration of essential functions, including ramps, speed limits, protection thresholds and remote control modes via logic or analogue inputs. Intelligent thermal management adjusts fan operation to limit unnecessary cycles, reducing mechanical wear and noise while preserving overload capability under demanded conditions. The range spans a wide power spectrum, facilitating part standardisation within a machine fleet, minimal spare stock and scheduled preventive maintenance. In automation architectures, COMMANDER SK integrates easily downstream of a programmable logic controller, an operator panel or a numerical controller, and can coexist with other drives or powertrain equipment. For existing production lines, adopting it minimises electrical and mechanical requalification, speeding up return to service after incidents and securing equipment availability.

• COMMANDER SK for general applications : reliable speed control, optimised energy efficiency across varying load profiles, simplified maintenance
• DIGIDRIVE SK compatibility depending on markets : comparable product philosophy, compactness and direct configuration, technical continuity for upgrades or replacements

The SK3403 model fits this versatile AC drive approach, meeting common variable-speed requirements without resorting to a servo drive, while retaining adjustment margins to tune the response to the process.

Industrial applications

Thanks to its sizing and proven basic features, the SK3403 covers a range of scenarios found in workshops and utilities. The 380-480 V AC supply range and the roughly 22 kW power rating suit flow and translation drives, with simple control from a programmable logic controller or a local panel. Typical uses include energy consumption control and flow stabilisation, belt speed regulation or air flow control, with reproducible commissioning between sites.

• Centrifugal and positive displacement pumps : fine tuning of operating point, mitigation of water hammer through controlled ramps
• Industrial ventilation and HVAC : air flow adaptation, noise and energy reduction at partial loads
• Conveyors and continuous handling : control of belt speeds, simple synchronisation via analogue setpoints
• Process machines : mixers, grinders, vibrating hoppers with speed adjustment according to recipe
• Plant utilities : compressors, auxiliary equipment requiring soft start and current limiting

Integration and communication

The SK3403 integrates into automation architectures via logic inputs, analogue inputs and relays, allowing direct control from a PLC, a numerical controller or an external control loop. Depending on versions and options, communication modules can be added for data exchange over common industrial buses to centralise setpoints and status feedback. This approach simplifies multi-site standardisation and traceability of key parameters in supervision systems.

Commissioning is performed via the local operator panel and manufacturer software tools when available. Critical parameters such as ramps, speed limits, maximum currents and thermal protections are accessible and documented. Best practices include motor characterisation, setting the carrier frequency according to the EMC environment and validating safety logic states. This methodology reduces downtime and secures drive behaviour during transients.

Availability and warranty

The Control Techniques SK3403 drive is offered by Standard Exchange Industry as refurbished supply, exchange unit or repair, each solution bench-tested. Shipping is provided within 24 to 72 hours to over 120 countries, with 6 to 24 months warranty depending on the chosen service. Our technical teams support reference selection, parameter recovery and substitution if necessary, to reduce MTTR and restore your line productivity. In obsolescence situations, we analyse mechanical and electrical compatibility to provide a reliable, documented return to service in line with your QSSE process requirements.