OQ Series

Up to 500kV Regulated High Voltage DC Power Supplies

The LH open stack family,  are sophisticated 4 kW power supplies with extremely low ripple and noise. They are air insulated fast response units with tight regulation. LH open stack series models consist of a rack style driver chassis, a high voltage stack assembly, and a remote control unit.


Specifications apply from 5% to 100% rated voltage. (Operation is guaranteed down to zero voltage with a slight degradation of performance.)

  • Input: 187-228 V RMS, 3Ø, 48-63 Hz, 13 kVA maximum at full load. Less than 40A/Ø at 208 VAC. A five-position terminal block with protective cover is provided. Mains service must be protected with fuses or circuit breakers with a maximum rating of 125 A for 208 VAC models & 100 A for 380 through 480 VAC models.
  • Efficiency: Typically 80% at full load
  • Output: Continuous stable adjustment from 0 to rated voltage or current by panel mounted 10-turn potentiometers with 0.05% resolution, or by external 0 to 10 V signals is provided. Repeatability better than 0.1% of setting. Voltage accuracy is 0.5% of setting + 0.2% of rated.
  • RS232/USB/Ethernet Programming and Monitor Accuracy: The front panel of this assembly contains: separate 10-turn controls with locking vernier dials used to set the voltage and current levels, High Voltage ON switch, High voltage OFF/Reset switch and an AC power on/off switch and indicator. LED‘s indicate when the high voltage is on, output polarity, interlock status, fault status, and whether the supply is operating in a voltage or current regulating mode. Output levels are indicated by voltage and current digital meters.The rear panel of this assembly contains AC Power On indicator, ground stud, driver/control chassis interface connectors, current limit/current trip selector switch, remote user interface connector and RS232/USB connectors.


  • Arc Quench: The HV output is inhibited for a short period after each load arc to help extinguish the arc
  • Embedded Microcontroller Control: Integral RS-232, USB and optional Ethernet communications provide remote control program and monitor
  • Air Insulated: The OQ Series features “air” as the primary dielectric medium. No oil or encapsulation is used to impede serviceability or increase weight
  • Low Ripple: Typically, ripple is less than 0.1% peak to peak of rated voltage at full load
  • Parallelable: One master supply and up to 4 slave supplies provide a maximum of 25 – 40 kW depending on kV
  • Pulse-Width Modulation: Off-the-line pulse-width modulation provides high efficiency and a reduced parts count for improved reliability
  • Constant Voltage/Constant Current Operation: Automatic crossover from constant-voltage to constant-current regulation provides protection against overloads, arcs, and short circuits
  • Constant Current/Current Trip: A rear panel selector switch on the remote chassis allows selection of either current mode
  • Tight Regulation: Voltage regulation is better than 0.005% for allowable line and load variations. Current regulation is better than 0.1% from short circuit to rated voltage

Specifications Table

See Datasheet
Input Voltage:
187-264 VAC, 3 Phase (See Datasheet for more options)
Up to 85%
Operating Temp:
-20 to +40 °C
Worldwide Safety Approvals:
EN61000-6-4:2007, Class A