PS300 High Voltage Power Supplies

Select the model by considering the required polarity, maximum voltage and load current together. The PS310, PS325 and PS350 provide dual-polarity ranges of ±1.25 kV at 20 mA, ±2.5 kV at 10 mA and ±5 kV at 5 mA respectively, while the other models provide fixed positive or negative outputs at 10 kV or 20 kV. The dual-polarity instruments use a polarity selector and must be powered down before the polarity is changed. They should therefore be used where either polarity is needed between test runs, rather than for rapid electronic polarity reversal. Allow current headroom for the load and connected high voltage cable when making the final selection.

Yes, the programmable current limit allows the supply to regulate by reducing its output voltage when the load attempts to draw more than the selected current. The current limit can be set from zero to 105% of full scale, while the separate current-trip threshold extends from 10 µA to 105% of full scale. A current trip disables the high voltage instead of maintaining current-limited operation, with response times below 10 µs for the 25 W models and below 10 ms for the 10 W models. Manual and automatic reset modes determine how the instrument responds after a trip. Use current limiting for controlled constant-current operation and the trip function when the test requires a complete shutdown after an overload.

Automation can be implemented through either a digital interface or the rear-panel analogue connections. GPIB is optional on the PS310, PS325 and PS350, while the PS355, PS365, PS370 and PS375 include both GPIB and RS-232 as standard. The RS-232 port operates as DCE at 9600 baud with no parity, eight data bits and one stop bit. An external 0 to 10 V DC signal can also programme the output from zero to full scale through a 1 MΩ input. The 10 W models provide 87.5 Hz analogue input and monitor updates, whereas the 25 W models update the set input at 16 Hz and the monitor outputs at 8 Hz.

Allow the instrument to warm up for one hour before relying on its rated performance. Voltage can be entered and displayed with 1 V resolution, but absolute accuracy also contains a full-scale component: 0.01% plus 0.05% of full scale for the 25 W models and 0.06% of full scale for the 10 W models. Line regulation is 0.001% for a ±10% line change, while load regulation is 0.005% for the 25 W group and 0.04% for the 10 W group. Regulation applies above approximately 0.5% of full scale at full load and 1% at no load. When working near the lower end of a model’s range, calculate the full-scale error rather than considering only the 1 V resolution.

No, the high voltage output and the rear-panel BNC shields are connected to chassis and protective earth, so these supplies cannot be operated as floating sources. The installation must use a correctly earthed three-wire mains connection and must not apply an external voltage to the BNC shields. Connector type also depends on the model group, with different Kings high voltage connectors used for the 5 kV, 10 kV and 20 kV ranges. High voltage cables can retain hazardous charge after being disconnected. Although the typical no-load discharge time is below six seconds to less than 1% of full-scale voltage, always verify that the output and cable are fully discharged before handling the connection.

The 25 W models provide reversible polarity and higher current, making them suitable for tests that need up to 20 mA at lower high-voltage ranges. The 10 W models extend the output to fixed-polarity 10 kV and 20 kV levels, with maximum currents of 1 mA and 0.5 mA respectively. The 25 W group has a faster current-trip response below 10 µs, but its analogue monitoring and set-input update rates are 8 Hz and 16 Hz. The 10 W group uses an 87.5 Hz update rate and provides typical high voltage slew rates of 7,000 or 14,000 V/s. Interface requirements also matter because RS-232 is fitted only to the 10 W instruments.

Up to nine complete instrument configurations can be saved in non-volatile memory and recalled from the front panel or a computer interface. Stored configurations can include the voltage set-point, voltage limit, current limit, trip threshold and reset mode, reducing the need to re-enter parameters between established procedures. The high voltage is off whenever the unit powers up, and recalling a stored configuration also turns the output off before the settings are applied. Configuration zero recalls the factory default state rather than a user preset. In automated fixtures, the controlling software should still read back the programmed limits and output state before enabling high voltage.