Historical Survey
The development of semiconductors began with the discovery of the transistor and diode in 1948. By the late 1950s, the need for specialized semiconductor protection fuses emerged due to the limitations of ordinary fuses. Initially, M-shaped knives were used, but due to poor conductivity, S-shaped knives were introduced in 1973, followed by G-shaped terminals for better connections.

Introduction
ULTRA-QUICK fuse links are designed to protect sensitive power semiconductors like diodes and transistors from overloads. These fuses must act quickly, have a low operating Joule integral, low switching overvoltage, and low power dissipation. They comply with DIN 57636/VDE 0636 standards and are marked for easy identification. This document serves as a guide for using the ULTRA-QUICK catalogue in designing protection systems for power semiconductors.

Fusing Characteristics
Fusing characteristics graphically represent the dependence of fusing time on load current. The gR characteristics provide protection over the entire current range, while aR characteristics protect semiconductors within a specific current domain. ULTRA QUICK fuses are manufactured with gR characteristics up to 100A and aR for higher currents.

Cut-off Currents and Breaking Capacity
ULTRA QUICK fuses limit short-circuit currents, reducing the dynamic strength requirements of protected devices. The breaking capacity indicates the fuse's ability to interrupt currents from the lowest melting current to the rated breaking capacity. The calculated breaking capacity for certain models is 200kA AC, with a measured capacity of 100kA AC.

I2t Values
The I2t value, or Joule integral, measures the energy flowing through the fuse and the protected semiconductor. It is crucial for short fusing times and is compared with the permissible integral of the semiconductor. The ULTRA QUICK catalog provides these values for different input voltages.

Power Dissipation and Switching Voltage
Semiconductor protection fuses have higher power dissipation than installation protection fuses, requiring consideration of additional heating in rectifier housings. The switching voltage during the breaking process must be higher than the source voltage for successful arc extinction. ULTRA QUICK fuses ensure quick and reliable breaking at low arcing voltage.

Insertion of Ultra Quick Fuse Links
Fuses can be integrated into semiconductor rectifier circuits to protect against possible defects and ensure reliable operation.

Specifications and Procedures
The document discusses various types of converters including DC to DC and AC to AC converters. It highlights the importance of using line fuses in individual phases of a secondary circuit, individual fuses for semiconductor elements, and fuses in DC circuits. Examples of rectifier and inverter circuits are provided, detailing the effective current values and voltage ratios necessary for dimensioning fuse elements.

Faults and Protection
Potential faults in electric energy transformation devices are outlined, such as external and internal short circuits and inverter control faults. The document emphasizes the need for selective and efficient protection using fuse elements, ensuring that the operating integral of a fuse is less than the melting integral of a preceding fuse.

Dimensioning Example
An example is provided for dimensioning a three-phase bridge rectifier circuit, detailing the selection of line fuses, individual fuses, and DC circuit fuses based on current and voltage requirements.

Selectivity and Circuit Configurations
The document explains selectivity in fuse protection, highlighting the importance of the Joule integral and the conditions for series and parallel circuits of ultra-quick fuse links. It discusses the implications of series and parallel connections on voltage distribution and current handling.

Thermal and Load Considerations
Factors affecting fuse operation, such as ambient temperature, forced cooling, and thermal connection, are discussed. The document provides calculation examples for fuse elements under uneven operation and load surges, emphasizing the importance of considering thermal influences and load conditions.

Optimizing Semiconductor Protection
Guidelines for selecting fuse elements to protect semiconductor devices are provided, focusing on load current, operating voltage, and the Joule integral. The document stresses the limitations of fuse protection and the need for additional protective measures in circuitry.

DC Operating Conditions
The document notes that in DC conditions, the rated voltage is lower than in AC conditions, and it provides guidance on defining DC operating conditions based on the L/R circuit constant.

Specifications
The document provides typical L/R constant values for various equipment types, such as battery supply (<10 ms), bridge circuit (<25 ms), DC motor armature (20-60 ms), DC traction systems (40-100 ms), and DC motor field (1000 ms). It advises against using fuses in DC motor field circuits.

Fuse Element Operation Indicator
ULTRA QUICK fuse links include an optical operation indicator requiring a minimum of 12V for operation. Remote blown fuse signalization is possible with a microswitch NVS5.

Fuse Base and Current Limitation
Different fuse bases are specified for various fuse types, with current limitations provided for each. The document discusses the advantages of G-type knives for better electrical and thermal contact.

Fuse Disconnectors
Various types of fuse disconnectors are listed with their maximum current (Imax) and rated voltage, including PCF 10, VLC 10, VLC 14, VLC 22, VLD 01, and STV D02, with indicators such as LED or NEON.

Storage Recommendations
Fuses should be stored in dry conditions with relative humidity not exceeding 70% and temperatures between -40ºC to +85ºC. Vibration limits are specified.

Glossary of Terms
The document includes definitions for terms such as Arcing I2t, Pre-arcing time, Total operating I2t, Ampere Rating, Arc Voltage, Breaking Capacity, High Speed Fuses, Current-Limitation, Cut-off current, Overcurrent, Overload, Peak Let-Through Current, Power Factor, Power Dissipation, Prospective Short-Circuit Current, Recovery Voltage, Resistive Load, RMS Current, Semiconductor Fuses, Short-Circuit Current, Short-Circuit Current Rating, and Voltage Rating.