The Hall Element Method for Current Sensing

         6 Current Sensing Methods

A few months back, we posted a blog discussing the 6 different current sensing methods used in the current meters and sensors developed by Hioki.  Here, we’re highlighting the sensors that incorporate a Hall Element to detect current.

A Hall Element is a semiconductor sensor that applies the Hall Effect principle to measure the flow of current through a conductor via the magnetic field the current creates.

The advantages of using the Hall Effect to measure current are:

1. You can measure both AC and DC, generally up to several kHz
2. A Hall Element can be incorporated in an easy-to-use clamp-type design for safe testing and to avoid the need to cut the conductor being tested
3. The component is relatively inexpensive

On the other hand, the Hall Effect also poses the following challenges:

1. Due to the effects of the Hall Element's linearity and the magnetic core's B-H characteristics (relationship between flux density and magnetic force), Hall element sensors lack precision
2. Due to its inherent characteristics, Hall Element sensor operation is subject to drift caused by factors including temperature and variations over time, so it is more suitable for measuring and observing waveforms in locations where there is little temperature change
3. Because the magnetic core acts as a load, Hall Element sensors are generally limited to low-frequency bands

As mentioned above, AC/DC sensors using a Hall Element are subject to offset drift caused by variations in the ambient temperature, forcing measured values to shift, even when testing DC currents.  To address this issue, Hioki added an auto-zeroing circuit to cancel this offset drift in several new AC/DC sensors that effectively reduced drift to about 1/100 of its original magnitude. This technology is present in Models CT7731/CT7736/ CT7742, making them ideal for applications such measuring current in solar power systems over an extended period of time during which the temperature changes.  Read more about this technology and current sensor in this Technical Note.

To address accuracy and frequency bandwidth issues and deliver more advanced current probes while still leveraging the advantages of using the Hall Effect principle to detect current, Hioki combined the use of the zero-flux method with our proprietary Hall Element in the detection circuit to improve accuracy and widen the frequency range.

Higher accuracy and wider bandwidth enable researchers in the automotive and robotics industry to monitor current waveforms of control signals, as well as developers of wireless or medical devices to easily and safely measure standby or leak current using non-invasive testing methods.  These characteristics are reflected in the CT6700 and 327X Series Current Probes, and you can learn about more about the operating principle of the zero-flux design used in the CT6700/CT6701 in this Technical Note.

Hioki's core competency in current sensing technologies empowers us to leverage traditional testing principles while overcoming their inherent disadvantages to deliver state-of-the-art devices.