Impulse testing systems are designed to generate impulse voltages that simulate lightning strikes and switching surges. The complete test system consists of a charging rectifier, impulse stages according to the “Marx Circuit”, an impulse voltage divider and impulse voltage measurement system. The applications are defined by IEC, ANSI/IEEE and other national standards. Impulse Test Sets are also available as current impulse generators used primarily for surge arrestor testing. HV TECHNOLOGIES, Inc. has a long tradition of supplying impulse generators for HV applications as well as impulse test systems for the EMC, avionics, and military industries.
Impulse voltage test systems are used for lightning impulse testing and switching impulse testing of various insulation systems. These include distribution and power transformers, power cables, switchgear, and bushings, among others. Different models are available depending on the testing application, such as the maximum charging voltage required or the amount of impulse energy per stage. All voltage generators are based on MARX multiplier circuits. The stages in the impulse generator are connected and charged in parallel via the charging resistors. Charging time and charging voltage can be selected by the operator.
Impulse current generators are used for exponential current impulse (ECI) 1/20 µs, 4/10 µs, 8/20 µs and lightning current impulse (LCI) 10/350 µs applications with very high impulse current amplitudes. Impulse current testing is mainly used for testing arrestors and varistors, but is also ideal for testing building protection elements, airplanes, helicopters, and wind turbine blades, etc.
The HiAS™ 744 is the unique tailor made impulse analyzer for the industry. Haefely, the pioneer company for impulse testing since 1904, has been continuously developing and upgrading high-voltage impulse measuring/analyzing solutions over the years. The latest in a long line of distinguished impulse analyzers is the Highest Resolution Impulse Analyzing System HiAS™ 744. Haefely has set a new benchmark with unbeatable performance. The new front-end solution provides up to 16-bit resolution at 250 MS/s with the highest measurement accuracy.
Control systems for impulse generators are a crucial part of a complete impulse test system. From customized test procedures to measuring values and built in alarms the Haefely impulse control units can provide a reliable and advanced solution. These state-of-the-art industrial PC based and desk control systems are specifically designed for the needs of high voltage testing.
Impulse dividers are used in combination with the Impulse Voltage Generators to test HV apparatus such as Power Transformers, Instrument Transformers, Switchgear, Breakers, HV Cables, etc. Tests are conducted with lightning full or chopped waves, and/or switching impulses. All Haefely impulse dividers meet all requirements of IEC 60060-2 in particular those with respect to measuring accuracy and step response. All dividers are fitted on a mobile base frame.
The Haefely line of chopping or sphere gaps can be used for either AC or DC voltage calibration (according to IEC 60052) or as a load capacitor and to provide a chopped lightning impulse. Chopping gaps are an important part of a complete impulse test system when a chopped impulse is required.
The Recurrent Surge Generator 482 is a bench-top, one stage, low voltage equivalent of a high voltage impulse generator. Its wide range of applications includes the testing of models, the study of voltage distribution in high voltage windings during impulse voltage stresses, and the predetermination of the circuit parameters of impulse test plants. All impulse circuit elements and, therefore, all impulse forms may be varied within broad limits with selector knobs.
The Haefely RIC 422 calibrator is used for the supervision and calibration of all kinds of impulse measuring systems with the highest accuracy. The calibrator generates Lightning (LI), Switching (SI) and front-chopped Lightning (LIC) reference impulses according to the standards IEC 61083 and IEEE 1122. In addition, it can produce accurate DC voltages and unit steps. Combined with impulse analyzing system, the RIC 422 can execute a fully automated calibration procedure according to IEC 61083.