Rogowski AC current probes measure next-gen semiconductors

This latest addition to the company’s CWT range provides better common mode immunity to local high voltage transients, claims the company, while providing a more precise measurement delay, to improve power loss measurement in, for example, power semiconductors using SiC technology.

Engineers increasingly need the enhanced accuracy of a screened probe for measuring complex current waveforms in equipment such as uninterruptible power supplies (UPS) circuits, switched-mode power supplies and variable-speed drive (VSD) inverters. In these instances, high power density leads to high field strengths. Equally high speeds and high blocking voltages of silicon-carbide (SiC) devices require higher probe bandwidth and better common-mode immunity.

The wide-band, screened probe combines a shielding technique, utilising a low-sensitivity coil, and patented low-noise, signal-conditioning circuitry to boost immunity to local dV/dt transients while maintaining a small size, flexibility, and 3dB bandwidth of up to 30MHz for a 100mm coil. The probe’s coil is only 4.5mm thick with 5kV insulation voltage, and can handle maximum current slope of 100kA/µs.

The 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, freedom from flying leads, isolated measurement, high peak-current rating, and the ability to measure small AC currents in the presence of large DC current.

The company continues its research into screened Rogowski coils, which maintain a wide bandwidth and faster response times, with better immunity to interference. Managing director, Dr Chris Hewson, will present a paper on Tuesday, 16th May: ‘An Inverted Rogowski Coil – A High-Speed, Wide-Bandwidth Company Current Transducer with High Immunity to Voltage Transients’.