Isolated current probes eliminate ground loops

IsoVu isolated current probes from Tektronix isolate oscilloscopes from circuits used for EVs, motors, and power converters.

Trying to make shunt-based current measurements with a typical oscilloscope probe is essentially impossible. That’s because one side of the probe connects to ground through the instrument. Using an ungrounded power cord is anything but safe. Differential probes help, but they still provide a direct connection from the circuit under test to the oscilloscope. Typical current probes require you to break the circuit to clamp the probe around a wire. That changes the circuit’s characteristics.

Tektronix has introduced the IsoVue isolated current probes, which uses galvanic isolation to isolate the circuit from the oscilloscope. That isolation eliminates the possibility of ground loops that can interfere with your circuit and compromise safety.

Available in three bandwidths: 1 GHz, 500 MHz, and 250 MHz, the probes let you use 1X, 10X, or 100X tips, providing a wide range of current measurements. For example, with a 50 Ω shunt and a 1X probe tip, maximum current is 13 mA. At the top end with a 100X tip and a 15 mΩ shunt, the maximum current measurement is 3300 kA.

Common-mode rejection ratio (CMRR) at 1 MHz is 90 dB using a 1X probe tip. That specification drops to 70 dB with a 10X probe tip and 50 dB with a 100X probe tip. The current probes can operate on power circuits with voltages up to 1.8 kV. That’s enough to measure current from circuits that use SiC and GaN transistors used in EVs.

The probes are compatible with Tektronix 4, 5, and 6 series oscilloscopes. Including the B series. See Product tryout: Tektronix 4 Series B oscilloscope for a review.

Other measurement applications include: