SCHURTER APO Pyrofuse Brings Active Safety for High-Voltage Systems

By Tomáš Zedníček
3 hours Ago

SCHURTER has introduced a new fuse technology, the Pyrofuse-APO Series, designed to meet the increasing demand for reliable protection in high-voltage systems driven by electrification in industries like EVs, aerospace, and energy storage.

Key Features and Benefits:

Active Operation: Unlike conventional fuses, the APO operates actively. Upon detecting a short circuit or accident, a control unit triggers a micro gas generator.
Rapid Response: The gas generator creates high pressure to mechanically sever a copper busbar, achieving complete galvanic isolation in less than 2 milliseconds (with measured speeds as fast as 0.9 ms).
High Performance:
- Rated for operating voltages up to 1000 V.
- Supports continuous currents up to 400 A.
- Ultra-low internal resistance (micro-Ohms range) minimizes power loss and heat.
Safety & Design:
- High breaking capacity for extreme short-circuit conditions.
- Fully encapsulated design prevents the release of particles or gases.
- Compact design allows for easy integration and reduces stress on downstream components like contactors.

This technology aims to set a new safety benchmark for e-mobility and energy transition applications.

Overview: A New Benchmark in High-Voltage Protection

As global industries—from automotive to aerospace—rapidly transition toward electrification, the safety requirements for high-voltage systems have intensified. Schurter’s new Pyrofuse-APO Series represents a paradigm shift from traditional passive circuit protection to active safety. Designed specifically for the rigorous demands of electric vehicles (EVs), charging infrastructure, energy storage, and fuel cells, this technology offers a level of speed and reliability that conventional fuses cannot match.

Operational Mechanism: Pyrotechnic Precision

The core innovation of the APO series lies in its “active” triggering mechanism. Unlike standard fuses that rely on melting a detailed element over time due to thermal buildup, the APO reacts instantaneously to a digital trigger:

Trigger Event: In the event of a crash or short circuit, the system’s control unit sends a signal to the fuse.
Gas Generation: This signal activates an integrated micro-gas generator.
Mechanical Separation: Within milliseconds, the generator builds high pressure that drives a piston. This piston mechanically severs a solid copper busbar.
Arc Extinguishing: The electrical arc resulting from the cut is immediately contained and suppressed within a dedicated extinguishing chamber.
Result: The system achieves complete galvanic isolation in less than 2 milliseconds, with real-world performance measured as fast as 0.9 ms.

Technical Specifications & Efficiency

The APO Series is engineered to handle the high power density of modern electric architectures without compromising efficiency:

Voltage & Current: Rated for operating voltages up to 1000 V and continuous currents of 400 A.
Ultra-Low Resistance: The unit boasts an internal resistance in the range of only a few dozen micro-Ohms (µOhms).
Thermal Management: This exceptionally low resistance ensures that power losses are negligible and temperature rise remains minimal, addressing one of the common pain points in high-power management.

Safety, Robustness, and Design

Schurter has designed the APO to function safely even under extreme conditions:

Encapsulation: The unit features a fully encapsulated design, ensuring that no gases or particles are released into the surrounding environment during operation.
High Breaking Capacity: It is capable of safely interrupting extreme short-circuit currents that would overwhelm standard components.
Downstream Protection: Its rapid reaction time relieves stress on downstream components, such as contactors, potentially extending the lifespan and reducing the cost of the overall system architecture.