What is a current limiter? Common current limiters

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What is a current limiter? Common current limiters

Posted Date: 2024-02-07

A current limiter is an electronic component or device used to limit the flow of electrical current. Its function is to protect circuits and electrical equipment from damage by excessive current by impeding the flow of current.

Current limiters typically adjust the current flow based on specific conditions. When the current exceeds a set threshold, the current limiter introduces additional resistance or other forms of impedance to limit the flow of current. This current-limiting operation can help protect components in the circuit (such as electronic components, power supplies, motors, etc.) from undesirable conditions such as overloads and short-circuit faults.

There are many different types and implementations of current limiters. Here are some common current limiters:

1. Resistor current limiter: Limits the current by connecting a resistor in series. The resistance value of the resistor can be selected as needed.

A series resistor limits the flow of current by introducing a resistor with a larger value. According to Ohm's law, current equals voltage divided by resistance, so a larger resistance will cause a smaller current to flow. The series resistor dissipates the energy provided by the power supply through a voltage drop proportional to the current.

2. Fuse: A common overload protection device, which contains a fuse. When the current exceeds the rated value, the fuse will blow and block the flow of current.

A fuse contains a fuse inside, which is made of a specific material that heats up when the current exceeds the fuse's rating. As the temperature rises, the fuse melts and opens the circuit, cutting off the flow of electricity. This circuit break acts to limit the flow of current.

3. PTC thermistor: Under normal operating conditions, the PTC thermistor has a low resistance value, but when the current exceeds the rated value, it heats up and rapidly increases the resistance value, thereby limiting the current flow.

The resistance value of a PTC thermistor increases with temperature. Under normal operating conditions, the PTC resistor is in a lower resistance state. But when the current exceeds its rating, the PTC thermistor heats up, causing the temperature to rise. As temperature increases, the value of resistance increases significantly, limiting the flow of current.

4. Electronic current limiter: A current limiter that uses electronic components (such as transistors, field effect tubes, etc.) to control the flow of current. This type of flow restrictor typically provides more precise and adjustable flow restriction.

Electronic current limiters use electronic components such as transistors, field effect transistors, etc. to control the flow of current. By changing the working state of electronic components, such as changing the base voltage, gate voltage, etc., the size of the current can be adjusted. These electronic components control the current in different ways, for example by adjusting its on and off states.

5. PWM (Pulse Width Modulation) current limiting principle: PWM technology controls the average current by quickly switching the power supply on and off. By changing the width of the pulse, that is, the duty cycle, the size of the current can be adjusted. In specific applications, PWM signals control the on-off state of switching devices (such as transistors), causing current to flow in the form of rapid switching cycles, thereby controlling the size of the current.

Current limiters are widely used in various circuits and applications. They can play an important role in circuit protection, power management, motor control and equipment protection in domestic, commercial and industrial environments.

Review Editor: Huang Fei

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