Four voltage converters PNTT-630 (thyristor type voltage converters) for mixer heating control

The converter is developed specifically for operation under conditions of casthouse production. It allows to perform smooth control of heating of mixer roofs with the use of the phase control method. It is applied under conditions of increased dust content and high ambient temperatures (up to +60°C). The types of powered heaters are the arch roof and tubular electric heaters.


Change of outdated equipment for mixer heating control with the aim to increase reliability and accuracy of output voltage control for a further changeover to tubular heaters


RUS-Engineering LLC for RUSAL Krasnoyarsk JSC, Casthouse No. 3, mixer No. 4

Project year:


Problems prior to implementation:

  • Unstable operation of the control system and frequent emergency shutdowns
  • Short life of heaters because of the use of the integer-value control method
  • Long downtime during maintenance
  • Frequent overheating of the power part

Key features:

  • Rated operational current is 630 A
  • Location in the Rittal cabinet (IP54)
  • Block control system BUT-3/U1 (IP66)
  • Russia produced semiconductor devices and fuse
  • Forced air cooling of power assemblies
  • Operation at the ambient temperatures up to +60°C
  • Control system with adjustable user settings
  • Functions of self-testing and monitoring of operation load (short circuits, open circuits, excess of operating current, etc.)
  • Work with diagrams of power supply: “star without N”, “star with N”, triangle, 1, 2 or 3 phase loads
  • Local or remote control with signals 4…20 mA, 0…10 V or by ModBus RTU interface


  • Accurate control of output voltage in case of poor network quality
  • Reduction of downtime in case of replacement of thyristor modules to 12 minutes
  • Possibility of heating control of tubular heaters
  • High level of maintainability and easy maintenance
  • Possibility of integration into the plant information network

Similar Projects

The launder with sliding mold tray and filtering box

Laboratory Casting Plant

Launder convection heating unit

Alloying bar feed unit