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Current sensor details

Article source: Shenzhen XinRuiDa Electric Power Equipments Co., Ltd.Popularity:3438Time:2016-10-27SmallInLarge

What is the current sensor definition?
Current sensor is a detection device, can feel the measured current information, and can detect the sensed information, according to a certain law into a certain standard needs to meet the needs of the electrical signal or other forms of information output to meet the information Transmission, processing, storage, display, recording and control requirements. Is a classification of sensors, the main signal source is the size of the current signal acquisition! The main parameters for the current size! Detection method is generally the characteristics of the current detection devices, such as ammeter in general!

What is the other name of the current sensor?
Current sensors, also known as magnetic sensors, can be used in home appliances, smart grid, electric vehicles, wind power, etc., in our lives are used a lot of magnetic sensors, such as computer hard drives, compasses, household appliances and so on.

How does the current transducer work?
The working principle of the current transducer is mainly the Hall effect principle.

Take zero flux closed-loop product principle as an example:

1, when the original side of the wire through the current sensor, the primary current IP will produce magnetic lines of force, the original magnetic field concentrated in the core around the air gap, built-in magnetic gap in the Hall film can be generated and the primary magnetic line is proportional to , The size of only a few millivolts of induced voltage, through the follow-up electronic circuit can be this tiny signal into a secondary current IS, and the following relationship: IS * NS = IP * NP where, IS-secondary current; NP-primary-side current; NP-primary coil turns; NS-secondary coil turns; NP / NS-turns ratio, the general take NP = 1. Current sensor output signal is the secondary current IS, Signal (the primary current IP) is proportional to the IS is generally very small, only 10 ~ 400mA. If the output current through the measurement resistance RM, you can get a proportional to the primary current of the size of a few volts of voltage output signal.

2, the sensor supply voltage VA VA refers to the current sensor supply voltage, it must be within the scope of the sensor within the scope of the sensor does not work or reduce reliability, In addition, the sensor supply voltage VA is divided into positive supply voltage VA + and the negative supply voltage VA-. It should be noted that single-phase power supply of the sensor, the supply voltage VAmin is two-phase supply voltage VAmin 2 times, so the measurement range should be higher than the dual-power sensor.

3, measuring range Ipmax measuring range refers to the current sensor can measure the maximum current value, the measurement range is generally higher than the standard rating IPN.

Hall current sensor main characteristic parameter is?

1, the standard rated IPN and rated output current
ISN IPN refers to the current sensor can test the standard rating, expressed as effective value (Arms), IPN size and sensor product model. ISN refers to the current sensor rated output current, usually 10 ~ 400mA, of course, according to some models Specifics may vary.

2, the offset current
ISO bias current is also called the residual current or residual current, it is mainly by the Hall element or electronic circuit in the operational amplifier instability caused by the current sensor in the production, at 25 ℃, IP = 0 circumstances, The offset current is minimized, but the sensor will have a certain amount of offset current when it leaves the production line. The accuracy mentioned in the product documentation has taken into account the effect of the offset current increase.

3, linearity
Linearity determines the sensor output signal (secondary current IS) and the input signal (primary current IP) is proportional to the extent of the measurement range.

4, the temperature drift
The offset current ISO is calculated at 25 ° C and changes in ISO as the ambient temperature of the Hall electrode changes. Therefore, it is important to consider the maximum variation of the offset current ISO, where IOT is the current sensor The temperature drift value in the performance table.

5, overload current sensor overload capacity is the occurrence of current overload, the measurement range, the primary current will still increase, and the duration of the overload current may be very short, and the overload value may exceed the allowable value of the sensor, overload Current sensor is not generally measured, but will not cause damage to the sensor.

6, precision
The accuracy of the Hall-effect sensor depends on the standard rated current IPN. At + 25 ° C, the accuracy of the sensor measurement has a certain influence on the primary current, and the influence of the offset current, linearity and temperature drift must be taken into account.

Current sensor applications in which areas?

Current sensors used in wind power: wind energy as a clean renewable energy, more and more attention from around the world. The huge amount of wind, the global wind energy is about 2.74 × 109GW, which can be used for wind energy 2 × 107GW, than the earth can be developed using the total amount of water even 10 times larger. The wind has been used for a long time - mainly through windmills to pump water, grinding, etc., and the new century, people are interested in how to use wind to generate electricity, and how to maximize power generation. Current sensor as the main detection components, in which play a crucial role.

Open-loop current sensor principle: the primary current IP flux generated by high-quality magnetic core gathered in the magnetic circuit, the Hall element is fixed in a small air gap, the magnetic flux of linear detection, Hall device output Hall voltage after a special circuit processing, the secondary output of the output waveform with the original follow the same output voltage, the voltage can accurately reflect the changes in the primary current.