JU Series Single-Phase Thyristor Regulators

The JU series small and lightweight thyristor regulators for single-phase loads are characterized with high panel installation density. Two control systems, a phase-angle firing system and a zero-cross firing system, are built in and can be changed by remote contacts signal.



  • Compact structure
    Compact, lightweight and high panel installation density
  • Options
    The options of heater disconnection alarm function and current limit function are available.
  • Phase-angle firing/zero-cross firing
    The phase-angle firing system and the zero-cross firing system are selectable. The running by the phase-angle firing system at the initial stage and by the zero-cross firing system at the normal stage is possible.
  • Zero-cross firing system
    With the delta-sigma modulation, which controls every 1 cycle, the fine control like the phase-angle firing system is possible.
  • Setting unit (option)
    Display of various parameters, voltage/current/ power and change of the feedback system are possible.
  • Various protections functions built-in
    The thyristor element is protected by melting of the rapid fuse for short-circuit of load, and by gate-off for over-current. For models with a cooling fan built-in, alarm is activated and output is stopped for abnormal heat-sink temperature.
  • Self-diagnosis function built-in
    The self-diagnosis function is built in for abnormal operation, abnormal thyristor element and abnormal power supply.


Phase Single-phase
Rated current 10, 20, 30, 50, 75, 100, 150, 200, 250, 300, 400, 500, 750, 1000A (to be specified)
Rated voltage 100, 110, 120, 200, 220, 240, 380, 400, 440VAC (to be specified)
Rated frequency 50/60Hz (automatic change)
Allowable frequency fluctuation ±2Hz of rated frequency (±1Hz for performance guarantee)
Working temperature range -10 to 55°C (0 to 50°C for performance guarantee)
Input signal Selectable on terminals of 4 to 20mADC (internal resistance 100 Ω), 1 to 5VDC (internal resistance 25k Ω), ON-OFF contact signal, and Resistance signal (10k Ω, manual)
Output range 0 to 98% of rated voltage
Minimum load current 0.5A or more (at 98% output of rated voltage)
Applicable load Resistive load, inductive load (primary side control of transformer, phase-angle firing system only)
Output control system Phase-angle firing/zero-cross firing (selectable depended on models)
Over-current protection Thyristor gate-off (120% or more of rated current, on built-in or external CT)
Cooling system Natural cooling for 150A or less of rated current Built-in cooling fan for 200A or more
Other functions Soft-start, soft-up/down (1 to 20 seconds), soft-start at power failure recovery
Dimension H150 x W70 x D165mm (for 10A, 20A)
H352 x W60 x D190mm (for 35A to 75A)
H325 x W128 x D190mm (for 100A to 250A)
H495 x W128 x D230mm (for 300A to 500A)
H495 x W260 x D350mm (for 750A, 1000A)
Weight About 2kg for 10A, 20A, about 3kg for 30 to 75A, about 7kg for 100 to 250A, about 12kg for 300 to 500A, about 35kg for 750A, 1000A