1, internal arrangement difference:
Due to the blocking and exposure of magnetic field and magnetic circuit, Hall sensor changes gradually, just like a door opens gradually no matter how fast it opens. The Hall signal of Hall sensor is very weak-it belongs to analog signal, and it is chopped and shaped by Schmidt trigger after being amplified and fed back by the sensor.
Most magnetic pulse sensors are coils containing only magnets. The coils of these sensors are thousands to tens of thousands of turns, and the wires are as thin as 0.03 ~ 0.07 mm. The length and thickness of wires are different, resulting in a resistance as high as several hundred Ω ~ 2000 Ω. When the ferromagnetic material is close to and away from the magnetic head, the coil generates current, which can be observed by pointer instrument, digital instrument and oscilloscope. The frequency and amplitude in a certain range are positively related to the speed.
2. Different wiring modes:
Hall type is an active sensor, which needs three leads: power supply Vc(+5v~+6v~+9V~+ 12v), grounding and signal output. Connect the power supply and ground wire according to the required voltage.
Most magnetic pulse sensors are coils with only magnets, both ends of which are effective. The third one is a grounded shielded wire, which may be connected to the signal ground. Some magnetic pulse sensor components are integrated with the amplification-limiting trigger shaping circuit, so the output becomes the same pulse signal as the above-mentioned Hall sensor.
3. Difference of output mode:
Sensor Hall signal terminal has two output types:
1, directly output 0. 1V/4.8V- high and low voltage changes of rectangular wave shaped digital pulse signal. You can use iron to approach and stay away from the sensor head and observe the voltage jump change of the signal terminal or use an oscilloscope, which should have rectangular waves; Amplitude has nothing to do with speed.
2. The last stage inside the sensor is OC gate-open collector gate, so the signal terminal will not output high potential, but only output an on-off signal to the ground. You can use pointer multimeter intelligent resistance file to measure the on/off, or use 2kω~ 20kω resistor to connect the signal terminal with the positive power supply, the so-called pull-up resistor, and then detect the signal voltage change.
A single component of the magnetic pulse sensor is integrated with limiting amplifier, trigger shaping and other circuits, so that the output becomes the same pulse signal as the above-mentioned Hall sensor. If only the limiting amplifier-trigger shaping circuit is integrated inside, the output signal will not keep two levels, that is, it will return to high level or low level when it stops running.
Extended data:
Matters needing attention of Hall current sensor
1, the current sensor must be correctly selected according to the rated effective value of the measured current. Long-term measurement of excessive current will damage the terminal power amplifier tube (magnetic compensation type). Under normal circumstances, the duration of double overload current shall not exceed 65438 0 minutes.
2. The voltage sensor must be connected in series with a current-limiting resistor R 1 on the primary side according to the product description, so that the rated current can be obtained on the primary side. Under normal circumstances, the duration of two overvoltage shall not exceed 65438 0 minutes.
3. The best accuracy of current and voltage sensor is obtained under the condition of primary rating, so when the measured current is higher than the rating of current sensor, the corresponding large sensor should be selected; When the measured voltage is higher than the rated value of the voltage sensor, the current limiting resistor should be readjusted. When the measured current is lower than the rated value 1/2, in order to obtain the best accuracy, the multi-turn method can be adopted.
4. Sensors with insulation and withstand voltage of 3KV can work normally for a long time in AC systems and DC systems below 1KV and sensors below 1.5KV in AC systems below 2KV and DC systems below 2.5kV. Be careful not to use them under overpressure.
5. When used on devices requiring good dynamic characteristics, it is best to use a single copper-aluminum bus bar and match the aperture. More turns, not less, will affect the dynamic characteristics.
6. When used in a high current DC system, if the working power supply is open or fails for some reason, the iron core will produce a large remanence, which is worth noting. The remanence will affect the accuracy. The method of demagnetization is to apply alternating current to the primary side without working power supply and gradually reduce its value.
7. The ability of the sensor to resist external magnetic field is: 5 ~ 10 cm away from the sensor, and a current twice the current value of the primary side of the sensor can resist magnetic field interference. When connecting three-phase high current, the phase-to-phase distance should be greater than 5 ~ 10 cm.
9. The magnetic saturation point and circuit saturation point of the sensor make it have strong overload capability, but the overload capability is limited by time. When testing the overload capacity, the overload current for more than two times shall not exceed 65438 0 minutes.
10, the primary current bus temperature cannot exceed 85℃, which is determined by the characteristics of ABS engineering plastics. Users have special requirements and can use high temperature resistant plastic as the shell.
Baidu encyclopedia-current sensor
Baidu Encyclopedia-Hall Current Sensor