The main activity of the High Voltage Measurement Reference Laboratory (CA2), opened by Cepel in 1996, is high voltage calibration of systems for measurement of full lightning impulses, switching impulses, high voltage alternating current (HVAC), high voltage direct current (HVDC), current impulse, among others, used mainly in industrial laboratories, electrical equipment manufacturers, electricity utilities and research institutions.
Located in the Adrianópolis Unit, CA2 is accredited since 2008 by the Brazilian National Institute of Metrology, Quality and Technology (Inmetro) for measurement of high voltage in alternating current at industrial frequency (60 Hz) between 10 kV and 180 kV, in accordance with ABNT NBR ISO/IEC 17025.
The laboratory is currently undergoing accreditation by Inmetro for full and chopped lightning impulse voltages up to 2500 kV. The need to calibrate systems for high voltage measurements results from growing market demands for electrical materials and equipment including standards in the ABNT NBR ISO 9000 series, required by most countries importing Brazilian products and also by domestic consumers.
The laboratory also performs research and development of new devices and techniques for calibration and measurement applied to high voltage tests. It develops, builds and calibrates special devices such as standards for high voltage direct current, resistive dividers for lightning impulse and insulator puncture tests, attenuators, current and impedance shunts for radio interference voltage.
The laboratory targets accreditation for HVAC between 1.0 kV and 10 kV, capacitance between 1.0 kV and 200 kV, HVDC between 10 kV and 250 kV, switching impulse up to 2500 kV, current impulse up to 100 kA and short duration electrical currents up to 5000 A.
The laboratory is currently undergoing studies to implement the latest revisions in the standards IEC 60060-1/2010 and IEC 60060-2/2010.
CA2 has an area with internal dimensions of 12x11x7 m (height), intended for research on high voltage measurements and for housing the standards. The laboratory has at its disposal reference instruments and primary standards for HVAC, HVDC, full lightning impulse voltage, switching impulse, current impulse and impulse for insulator puncture.
The following equipment is available at the laboratory:
• 1000 kV, 50 kJ, 10-stage impulse generator
• AC voltage source up to 200 kV/1.5A
• Portable, modular DC voltage source up to 240 kV/4.1 mA
• 500 kV resistive voltage dividers
• 500 kV mixed voltage dividers
• System for acquisition and analysis of high voltage impulses
• 100 pF / 200 kV standard capacitors
• Transformers for current impulse up to 500 kA
• Current impulse calibrators up to 20 kA
• Voltage impulse calibrators up to 1900 V
• Alternating/Direct voltage calibrators up to 1000 V
• 1 GHz / 10 GS/s digital oscilloscopes
• Crest voltage meters for measuring impulses
• 8 ½ digit multimeters and precision RLC bridges up to 100 MHz
• Capacitance and tan delta bridge.
The available standards allow the calibration of systems approved for tests with voltage impulses with crests up to 2500 kV and systems for measuring current impulses with crests up to 100 kA.
Standards and/or procedures adopted
• IEC 60060-1/89
• IEC 60060-2/94
• ABNT NBR ISO/IEC 17025/2005
• Interlaboratory comparisons between primary standards and mutual recognition for lightning impulse measurements with various international laboratories, including: Physikalisch-Technische Bundesanstalt (PTB), in Germany; Helsinki University of Technology (HUT), in Finland; Centro Eletrottecnico Sperimentale Italiano (Cesi), in Italy; Keuring van Elektrotechnische Materialen (Kema), in the Netherlands; National Institute of Standards and Technology (NIST), in the USA; and L'Institut de Recherche d'Hydro-Québec (Ireq), in Canada.