Apa itu perlindungan arus berlebih?

Proteksi arus lebih merupakan mekanisme proteksi rangkaian yang digunakan untuk mendeteksi dan membatasi arus yang melebihi ambang batas yang ditetapkan untuk mencegah kerusakan komponen, risiko keselamatan atau ketidakstabilan sistem yang disebabkan oleh arus yang berlebihan. Berikut ini adalah analisa detail proteksi arus lebih:

1. ‌Basic concept‌
Overcurrent protection monitors the current value and triggers the protection device to operate (such as tripping or alarm) when the current exceeds the preset maximum value, thereby cutting off the fault circuit or reducing the risk. Its application scenarios include:

‌Perlindungan hubung singkat‌: For instantaneous large currents (such as direct contact of wires), respon cepat (microsecond level) is required.

‌Perlindungan kelebihan beban‌: For continuous over-rated current, an inverse time delay mechanism (such as thermal relay) is usually used.

2. ‌Working principle‌
‌Current detection‌: Real-time monitoring of current through sampling resistors, current transformers or integrated ICs (such as LT6100).
‌Trigger mechanism‌: Ketika arus melebihi nilai yang ditetapkan, the relay or circuit breaker operates and the circuit is disconnected.
‌Delay design‌: It is divided into three-stage protection (fast break, time-limited fast break, and time-limited overcurrent), taking into account selectivity and response speed.

3. ‌Implementation method‌
‌Discrete components‌: Such as a simple circuit built with a transistor + sampling resistor, which limits the current by clamping the voltage (Misalnya, a 1A threshold design).
‌Integrated solution‌:
‌PTC resettable fuse‌: The resistance value increases sharply when overcurrent occurs, and it automatically resets after the fault is eliminated.
‌Special protection IC‌: Such as the overcurrent, overvoltage, and overheating multiple protection circuits in the DC power conversion chip.

4. ‌Technical parameters and selection‌
‌Rated current/voltage‌: It needs to match the load requirements (such as 3A~25A, 125/250VAC).
‌Action time‌: Short-circuit protection needs to be ≤40ns, and overload protection can be delayed to seconds.
‌Menammental Adaptability‌: Consider the influence of conductor cross-sectional area and temperature on current carrying capacity.

5. Application Cases

Power system: Three-stage protection covers the entire length of the line and the backup area.

Electronic equipment: Misalnya, USB interface overcurrent protection prevents the motherboard from burning out.

Industrial motor: Combines multiple protection functions such as stall and phase failure.

The core of overcurrent protection is to balance sensitivity and selectivity, ensuring accurate fault isolation while avoiding false operation.