Precautions for Using High-Precision Current Sensors

Range, large capacity, power, voltage. The sensor range refers to the rated current for measurement, with values specified in the corresponding model description. Under any normal operating temperature, when the load resistance value and supply voltage meet the requirements, the sensor can perform full-scale measurements. The overload capacity is the measurement capability that the sensor can achieve within a specified time frame. Ideally, the measurement capability of the sensor is its capacity. The measurement capability is limited by the capacity of the power tube, which can only be used for a short period. The measurement capability cannot limit the measurement of pulse currents for extremely short durations.

The power consumption of high-precision current sensors mainly comes from the internal coils and the power tube, where the heat generated by the power tube can lead to temperature rise, and in severe cases, cause the power tube to overheat, reducing its lifespan or even damaging it due to overheating. To meet the measurement capability, especially for sensors operating in high-temperature environments, it is essential to ensure the normal operation of the sensor in high-temperature conditions, avoid energy waste, reduce inefficiency, and improve work efficiency. The power supply voltage values provided in the manual should meet the quantitative range. If the measured value is significantly below the measurement range, the supply voltage can be appropriately reduced, such as for a 15V sensor or a 10V low operating voltage, with a recommendation to keep it above 12V. The sensor uses a power supply of 18~24V, with a low operating voltage of 18V, which cannot be further reduced.

Excessive program control protection and self-recovery functions.

High-precision current sensors differ from traditional Hall current sensors. When traditional Hall current sensors exceed their measurement capacity, they can reach and maintain a magnetic saturation state, thus holding the output position. However, magnetic modulation sensors operate in a zero magnetic flux state, and when exceeding the measurement capacity, they enter a non-zero magnetic flux state and cannot remain at the output position. At this time, the internal self-recovery function is triggered, causing the output to enter a scanning state, independent of the input. At this point, the Valid indicator light goes out. The self-recovery function allows the sensor to immediately return to normal operating status (usually within 10 milliseconds) when the current on the primary side returns to the measurement value.

The load resistor RL can be connected in parallel with a reverse Zener diode or a bidirectional TVS tube. When the voltage across RL reaches the reverse conduction voltage of the diode, the diode conducts, acting as a variable resistor, at which point the output voltage of the sensor can be maintained at the output voltage position.

There is a limitation in the above methods, namely that the total resistance value of the RL parallel diode cannot be reduced to 0. If it exceeds the maximum measurement capacity determined by formula 1, the internal state remains in scanning mode. In unavoidable measurement situations, interruptions should be avoided as much as possible. Besides exceeding the range, factors such as different power-on times for positive and negative power supplies, and single power supply outages can also trigger the self-recovery function.