Drive System Modernization for SUT200 SKODA Lathe Spindle Rotation

The drive system overhaul for the spindle rotation of the SUT200 Skoda lathe involved implementing a new control cabinet equipped with a drive based on the modern Mentor MP 350A4R thyristor converter by Control Techniques (Nidec). This solution ensures precise control of the existing shunt-wound DC motor, type SKODA AN3234F/4 (Pn=80kW, In=240A, Un=375VDC, n=1000 rpm, n_max=2500 rpm).

The integrated Mentor MP digital drive delivers stable speed regulation by adjusting the armature voltage utilizing a feedback loop (tachogenerator/encoder). This represents a major technological leap forward compared to the original SKODA electro-mechanical Ward Leonard system. Maximum operational speeds are achieved through field weakening managed by the internal field current regulator of the Mentor converter.

Hardware Deployment Specifications:

• ✓ Control Cabinet: Schneider Electric enclosure, dimensions 2000x1200x500 mm, featuring forced ventilation and an integrated heating system.
• ✓ Main Disconnect Switch: Eaton NZMN3-AE400 circuit breaker.
• ✓ Main Converter: Mentor MP 350A4R (Control Techniques Nidec), Un=3x400V, In=350A, four-quadrant regenerative DC industrial drive equipped with an optional SM-I/O Plus extended I/O module.
• ✓ Protective Devices: Bussmann high-speed semiconductor fuse kit (400A) mounted in an Apator RBK 3 fuse switch disconnector, alongside a dedicated line reactor.
• ✓ Safety System: Certified Siemens 3SK1121-1CB42 safety relay with time-delay outputs.
• ✓ Switchgear & Control Components: Miniature circuit breakers, contactors, auxiliary relays, and a stabilized 24VDC system power supply.
• ✓ Rewiring: Full replacement of internal cabinet wiring and field instrumentation cables.
• ✓ Partnership: Project successfully executed in cooperation with Apator S.A. – May 2026.

Scope of Project Execution:

• ✓ Development of complete electrical schematics and documentation using the EPLAN Electric platform.
• ✓ Assembly of the control cabinet, field actuators, and comprehensive on-site automation system integration.
• ✓ Advanced parameter configuration of the Mentor MP drive, industrial commissioning, and full-load load testing of the spindle rotation loop.