Open Loop Hall Effect Current Sensors
(Current Sensing Transducers with Open Loop)

PCB Mounting Current Sensors

Rectangle Windows Current Sensors

Round Windows Current Sensors

Closed Loop Hall Effect Current Sensors
(Current Sensing Transducers with Closed Loop)

PCB Mounting Current Sensing Transducers

Rectangle Windows Current Sensing Transducers

Round Windows Current Sensing Transducers

Typical Applications

Current Sensing Techniques used by Current Sensing Transducers

Hall-effect sensors measure the magnetic field associated with current flow to measure a specific current. The most commonly used current sensing techniques are:

1. Resistive Current Sensing: Where the voltage drop associated with an electrical current flowing through a resistor is the basis for the measurement.
    

2. Free space current sensing: where a current sensor is created by placing a linear hall-effect sensor in proximity to a current-carrying conductor. The sensor shall be oriented so that the magnetic flux lines, can be detected
    

3. Toroidal Current Sensors: A current sensor may be made by placing a high-permeability toroid around a current-carrying conductor. In this case the flux flowing around the toroid will be significantly greater than that in the space around it. Being the conductor centered in the toroid, the toroid's presence will not alter the shape of the field. This is the preferred choice for most of applications, since free-space current sensors suffer from lack of sensitivity and also susceptible to outside interference.

BB Automacao Toroidal Hall Effect Current Transducers

Most manufacturers produce slotted toroids to accommodate several types of commonly available hall-effect IC packages. The usual magnetic gain for these transducers will be from 6 to 9 gauss per ampere.

The materials used for Current Transducers usually have a saturation flux density greater than the flux densities to be obtained in operation. This is justified by the fact the saturation begins to occur in many materials, with permeability decreasing as flux levels increase past a specific limit. When buying our parts, you are informed about the maximum number of ampere-turns that can be applied to our sensors before they begin to saturate.  It is interesting to note that permeability also can vary over temperature.  This issue is addressed in our transducers by the use of materials that have at least some permeability over the operating conditions under you are expected to operate your current sensor.
 

Improving Hall Effect Current Sensors sensitivity:

• using more sensitive magnetic transducer

• adopting narrower air gaps

• looping the conductors through the toroids (see Closed-Loop Current Sensors)

Threshold Sensitive Current Sensors/ Transducers

Also called on/off logic output sensors. These threshold current sensors are usually made by putting a switched digital Hall-Effect sensor in the toroid gap. This sensor turns on when the current exceeds a given threshold and turns off when the current drops below a second threshold.

Close-Loop Current Sensors / Transducers

Open-Loop sensors are the right choice for many applications. Nonetheless, Open-Loop sensors may not reach the linearity and gain requirements of some applications. Close-Loop Current sensors offer higher accuracy by correcting the linearity and gain errors through a negative feedback.

The feedback current is attached to the toroid through a separate conductor to counterpart the magnetic field being measured. Only a small current may be required, since the use of multiple turns will multiple this current. This technique enable the manufacturing of current sensors that can sense large currents without magnetically saturating the toroid or the Hall-effect sensor.

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