Monday, November 24, 2008

Ultra-High Voltage Transformer

A new transformer developed for the world’s first ultra high-voltage DC transmission systems (UHVDC) has successfully completed final testing. It is the first transformer for the new 800 kilovolts (kV) HVDC in China. Today’s HVDC transmission systems normally operate at a standard transmission voltage of 500 kilovolts. HVDC systems can transmit power over much greater distances and at considerably reduced loss than is possible with AC systems.

To achieve this 60-percent increase in peak voltage capacity, Siemens had to develop a range of entirely new technical solutions for the new 800-kilovolt HVDC transmission system. One of several major challenges facing the company’s development engineers in Nuremberg was a lack of any defined standards for this scale of system. Due to the very high operating voltage, for example, they had to design exceptionally effective insulation systems. Therefore, in order to achieve the needed insulating clearances in air, the two valve bushings through which the current flows from inside the transformer to the converters are 14 meters in length. To construct the 800 kV transformers, a new, specially air-conditioned production hall had to be built to prevent the insulation from absorbing moisture from the atmosphere during final assembly. Similarly, the test facility in the Nuremberg factory had to be adapted to accommodate the tremendous increase in voltage when carrying out final acceptance testing on the new transformer.

Monday, November 17, 2008

High Voltage Curve Tracer

Agilent Technologies Inc. recently introduced the industry's first power device analyzer/curve tracer able to characterize semiconductor devices at up to 3,000 volts and 20 amps.

Power devices, including power management ICs (PMIC) and power MOSFETs and motor control ICs used in cars, are a growing device category that requires both high-power and high-accuracy test. In order to meet emerging standards for low-carbon emissions and improved energy efficiencies, power devices must function more efficiently even as they continue to become more complex, smaller and faster. New devices using wide band gap materials such as silicon carbide (SiC) or gallium nitride (GaN) have been widely studied in order to achieve high efficiency. To enable the careful and precise testing to meet performance and safety requirements, these studies require high-voltage measurement capabilities greater than 1,000 volts. In addition, for those power-device developments, on-wafer testing becomes very important for reducing development turnaround times.

Featuring a curve tracer mode, the Agilent B1505A can replace curve tracers used in failure analysis, as well as in circuit design or power module development of electronic equipment makers.

Key Features of the Agilent B1505A Power Device Analyzer/Curve Tracer usful to high voltage engineers:
-- Accurate measurement of breakdown voltage and leakage currents at high voltage.
-- Sub picoamp level measurement capability at high voltage.
-- Capacitance-Voltage (CV) measurement with up to 3,000 V bias.
-- Device characterization at 3,000 volts and 20 amps in a single instrument.