SCR Stack Controller Model PLXD

The PLXD is used for controlling external 3 phase SCR (thyristor) stacks for DC drives. It is a fully digital controller and possesses all the functionality of the proven PL Series of DC drives. It can be used to replace older DC drive SCR stack controllers by interfacing directly to the SCR gates via a separate pulse transformer unit that can be located close to the SCRs for easy installation and reliable operation. It is drive.web compatible and uses the powerful savvy graphical configuration software tools.

The Compact PLXD controller can be used in either regenerative or non-regenerative configurations and has a built in automatic field controller, tach/encoder/armature voltage feedback and all the features of the high-performance PL Series DC drives.


  • Gate drive pulse current up to 1.5 Amps.
  • Terminal connections for:
    • Isolated armature current signal
    • Field signal
    • Thermal heatsink sensor switch
    • High voltage armature voltage feedback.
  • +24v supply for the gate drive pulse transformers – short circuit protected.
  • Stack configurations:
    • 6 pulse 2 Quadrant bridge (6 thyristors), or 2 bridges in parallel (12 thyristors).
    • 6 pulse 4 Quadrant regen anti-parallel bridge (12 thyristors). Extra stacks can be used in parallel within the gate drive capability.
  • Plug-in control terminals
  • Voltage ratings up to 690v AC on its 3 phase auxiliary supply inputs (EL1/2/3). The external stacks can be of higher voltages if required.
  • Armature voltage inputs up to +/-1000 Volts DC.
  • Integral motor field controller with independent single phase AC supply inputs:
    • Standard field rating up to 32 Amps.
    • Optional field rating up to 50 Amps.
    • Field bridge supply input voltage rating up to 480VAC.
  • Optional external field controller interface with feedback signal and external user supplied primary gate pulse transformer drivers.

The separate pulse transformer unit (Product code LA102800) contains all the external interface components required to combine the PLXD with the thyristor stack and its associated AC current transformers. It includes 12 pulse transformer networks for 2 or 4 quadrant bridges, an armature burden rectifier network, and 2 pulse transformer networks for an external field bridge. The unit is designed to be mounted on a DIN rail and all the interface connections are via screw terminals.

Options include:

  • dw111, speedy on board programmable controller with Ethernet, peer to peer networking and basic control function block library.
  • Process control function block library
  • Winder control function block library
  • Encoder control function block library
  • ModbusTCP/IP
  • ModbusRTU
Model PLXD
Model PLXD