Fusible DIAZED FUNCIONAMIENTO l Fusible tipo diazed explicado. Protecciones electricas baja tension
How Does a Fuse Work?
Introduction to Fuses
- The speaker introduces the topic by showing a clip of a fuse that exploded when it was closed, highlighting the importance of understanding fuses.
Basic Functionality of Fuses
- A fuse operates based on the Joule effect, where an internal wire or strip generates heat due to current flow. This heat can melt the wire, causing the fuse to open and stop current flow.
- When excessive current flows through a fuse beyond its design limit, the internal wire melts and breaks, preventing further current from passing.
Components of a Low Voltage Fuse
- The low voltage type diesel fuse consists of several parts:
- A ceramic body resistant to thermal shock.
- Bronze contacts with possible nickel or silver coatings for durability.
Design Features of Diesel Fuses
- The internal element is not just a wire but a thin strip with constrictions (angosturas) and holes designed to manage overload conditions effectively.
- There are two types of protection offered by these fuses:
- Backup protection against short circuits.
- General use protection against both short circuits and overloads.
Mechanism of Action During Overload and Short Circuit
- Under overload conditions, small pieces between holes in the strip can melt over time, leading to circuit opening.
- In case of a short circuit, the heat generated quickly melts the strip at its constrictions, resulting in an arc formation.
Arc Extinction Process
- To prevent large arcs that could damage components, multiple small arcs are created due to design features like holes and constrictions in the strip.
- An extinguishing element made from quartz sand surrounds this setup; when melting occurs due to arcing, it forms fulgurite—a dielectric material that helps extinguish electrical arcs.
Signaling and Breaking Capacity
- Most fuses have an indication mechanism; for example, when melted, they display a colored signal related to their nominal current rating.
- The breaking capacity varies among different types; for instance:
- NH type has a breaking capacity of 200 kA,
- Diesel type has a lower capacity at 70 kA.
Importance of Breaking Capacity