HALL EFFECT CURRENT SENSORS
Features:
• Measure: DC, AC, and Pulsed waveforms
• Galvanic Isolation
• Fast Response
• Zero Insertion Loss
• Cost Effective
Open Loop Operating Principle
With the Open Loop Hall effect current sensor, the magnetic flux, proportional to the primary current, is concentrated in gapped magnetic core containing the Hall effect device (Fig. 1). The primary current is measured without electrical contact with the primary circuit providing galvanic isolation. From Figure 1, the magnetic flux, concentrated in the gap of the magnetic core, induces a potential difference, Vh, the Hall voltage,given by the Vh=k*Ic*B. The output signal of the Hall device, Vh, is then further amplified by additional internal signal conditioning circuitry to provide an instantaneous output voltage proportional to the primary current.
Closed Loop Operating Principle
In a Closed Loop Hall effect current sensor the same principles apply as with the Open Loop type, however, with the addition of a secondary coil and feedback circuitry. The Closed Loop or ‘Zero-Flux’ Hall effect sensor feeds back an opposing current into a secondary coil wound on the magnetic core to zero the flux produced in the magnetic core by the primary current. The output current of a closed loop current sensor is an exact representation of the primary current scaled by the number of turns in the secondary coil. As with the Open Loop design the Closed Loop design provides galvanic isolation. The output of a closed loop current sensor can be scaled with the addition of a burden resistor, Rm1 , to produce a voltage level output proportional to the primary current.
1Burden resistor must be selected from within specified range – consult datasheet or contact Tamura technical support for assistance.
Application notes & tips:
1. Ensure power supply polarity is respected to prevent damage to
internal circuitry.
2. Non-linearity due to magnetic core saturation can occur at
primary currents in excess of 2X the nominal rated current.
3. Hall effect based current sensors are affected by static and
dynamic electric and magnetic field; use twisted and/or shielded
cables to mitigate these affects.
4. Frequency bandwidth in open loop current sensors is limited
at high frequency due to magnetic core losses and eddy current
induced temperature rise.
5. The Primary conductor should pass straight through the aperture
or, in the case of multiple primary turns, be wound around the body
of the current sensor.
6. Care in placement and orientation of the current sensors in presence
of high electromagnetic fields can lessen their effect on the current
sensor.
Datasheet - Download
Click here for the data sheets.