Electronic security

from Wikipedia, the free encyclopedia

The electronic fuse is a protective device that automatically switches off a circuit in the event of a short circuit or overload and is a form of overcurrent protection device . Compared to classic miniature circuit breakers , electronic overcurrent protection has the advantage that it trips very quickly and even with a low overcurrent. In this way, reliable shutdown can be ensured even with long lines and small line cross-sections.

construction

Circuit diagram of an electronic fuse
Electronic fuse block in a control cabinet

There are various ways of implementing electronic security. Different circuit types are used depending on the purpose (see example image). The fuse is connected with the connections U in to the higher supply potential and with U out to the device to be protected.

In the basic state, the current for the consumer can flow through the transistors V 2 and V 4 . Since the base-emitter voltages of these two transistors act in the opposite direction, only a small voltage loss occurs on these transistors. Nevertheless, you need power transistors in order to be able to supply the end device with enough power.

After triggering the circuit can be reset with S1.

application

Electronic fuses are used in devices that have to be built very compactly, may not have any mechanical components or where a classic fuse with the help of protective diodes or other protective circuitry alone is not sufficient, e.g. in power supplies and output stages (amplifiers). The electronic fuse also has a much faster response time than a thermomagnetic circuit breaker or a super-fast fuse .

In modern devices, finished electronic fuses are installed, which have many additional protective functions. These prefabricated components are not only installed in the power supply unit, but also on the respective circuit board of the actual device in addition to the protective capacitor.

Electronically controlled relay or protective contacts are also often referred to as electronic fuses. Ideally, however, such electromechanical contacts should only be designed in addition to ensure complete disconnection or galvanic separation .

Electronic fuses can also be integrated in electronic switches .

There are various designs for electronic fuses: The stand-alone variant combines all functions such as energy supply or signaling contacts in one device. With the modular variant, the various functions are represented by separate components. The modular variant with bus communication also offers the option of integrating bus communication into the system in order to simplify control and programming.

Web links

Commons : Electronic backup  - collection of pictures, videos and audio files

Individual evidence

  1. Michael Raspotnig, Ralf Higgelke: The better protection: Protection of 24 V load circuits. Retrieved April 1, 2019 .
  2. Best4Automation: Find the BEST electronic fuse. Retrieved April 1, 2019 .