CT6704 Current Probe

With the CT6704 model, HIOKI combines the fluxgate measurement principle, well known from power measurement applications, with the wide bandwidth of an oscilloscope current probe. This AC/DC current probe minimizes DC offset drift caused by temperature changes and self-heating while extending the usable frequency range at high currents. As a result, current can be measured with stable signal behavior even during long measurement periods and when capturing high-frequency signal components. The CT6704 measures currents up to 200 A rms with a maximum peak current of ±400 A over a frequency range from DC to 30 MHz. Rise time is 11.6 ns or less. The measurement signal is provided at a scaling factor of 10 mV/A through a standard BNC output, allowing direct connection to oscilloscopes, memory recorders, and other data acquisition (DAQ) systems equipped with a BNC input.

Video: Unique technology for eliminating temperature drift at higher frequencies and currents

Stable Signal Waveforms at AC Currents and High Frequencies

Fluxgate-based detection stabilizes the DC and low-frequency components of the measurement signal. The offset temperature coefficient is specified at ±0.1 mV/°C, ensuring that the measurement signal deviates only minimally due to changes in ambient temperature or self-heating effects. The specified operating temperature range extends from −10 °C to +50 °C. The usable frequency range at high currents is determined not only by bandwidth but also by the probe’s current derating characteristics. The CT6704 delivers its full rated current of 200 A rms up to 100 kHz without derating. This is achieved through an optimized magnetic and thermal design that reduces heating caused by high-frequency current components, allowing high currents to remain measurable well beyond 100 kHz within the specified derating limits.

Fig. Comparison of the measurement range with the previous 3274 model

System Connection and Integration

The CT6704 probe provides an output signal of 10 mV/A via a standard BNC connector, enabling direct connection to oscilloscopes, memory recorders, and DAQ systems with BNC inputs. For detailed visualization of current waveforms, fast transients, and long-duration measurement sequences, a high-resolution measurement system is recommended, such as the HIOKI MR6000 Memory Recorder. Power is supplied through a two-pin LEMO connector on the probe, either by the HIOKI 3269 Power Supply (when used with oscilloscopes from other manufacturers) or directly from the MR6000 when equipped with the Z5021 Probe Power Unit. A single 3269 power supply can operate up to three CT6704 probes simultaneously, while an MR6000 equipped with the Z5021 supports up to five probes. For accurate measurements, the CT6704 features demagnetization and automatic zero-adjustment functions, which are recommended before each measurement session.

The CT6704 probe is fully developed and manufactured at HIOKI’s own production facility in Japan. It complements HIOKI’s existing portfolio of current sensors, whose development has focused for decades on precise AC/DC current measurement and stable measurement signals for laboratory and R&D applications.