It is essential to measure fast current transients with good precision in power electronic applications, for example to determine switching loss in semiconductors, to monitor stress in bond wires in large power devices or to determine the effects of stray inductance on a circuit.
To meet the demands of measuring transient currents in semiconductors using new technology, such as SiC and GaN, Power Electronic Measurements Ltd (PEM) has designed the CWT MiniHF Rogowski current probe. Combining a novel shielding technique, utilizing a low sensitivity coil and patented low-noise signal-conditioning circuitry, the wide-band screened probe boosts immunity to local dV/dt transients while maintaining small size, flexibility, and 3dB bandwidth of up to 30MHz for a 100mm coil. The probes feature a coil only 4.5mm thick with 5kV insulation voltage, and can handle maximum current slope of 100kA/µs.
The new wide-band screened CWT MiniHF probe eliminates the extra bulk and bandwidth restrictions imposed by conventional screening techniques, while delivering the known advantages of a Rogowski coil. These include zero insertion impedance, isolated measurement, high peak-current rating, and the ability to measure small AC currents in the presence of large DC current.
This current probe not only provides better common mode immunity to local high voltage transients, it also has a consistent delay when monitoring fast transients which can be compensated for to give improved power loss measurement in power semiconductors such as SiC and GaN.