Wide-band screened current probes boost accuracy in harsh electrical environments

May 21, 2014 // By Graham Prophet
Wide-band screened CWT Mini Rogowski current probes from Power Electronic Measurements (PEM) use an electrostatic screening strategy that enhances performance and accuracy in the presence of large electrostatic interference signals.

Its shielding technique, using a low sensitivity coil and low-noise signal-conditioning circuitry, gives the wide-band screened CWT Mini probe improved immunity to local dV/dt transients while maintaining small size, flexibility, and 3dB bandwidth of up to 30 MHz for a 100 mm coil. The probes feature a coil 4.5 mm thick with 5 kV insulation voltage, and can handle maximum current slope of 70 kA/µsec.

The enhanced accuracy of a screened probe is required for applications such as measuring complex current waveforms in equipment such as UPS circuits, switched-mode power supplies and Variable-Speed Drive (VSD) inverters where high power density leads to high field strengths, or where the high speeds and high blocking voltages of silicon-carbide (SiC) devices call for higher probe bandwidth and better common-mode immunity.

The CWT Mini probes eliminate 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.

PEM; www.pemuk.com