A fuse-link is a passive protection device that must work flawlessly every single time. There is no room for error. Tests and certifications ensure that every manufactured batch complies with the strict requirements of international standards and the operating conditions of real networks.
1. Breaking capacity test
This is the most complex and costly test: the fuse must interrupt a very high short-circuit current (e.g., 50 kA).
A real electric arc is generated, which must be extinguished within milliseconds.
The integrity of the tube and the complete interruption of current are verified.
2. Heating test at rated current
The rated current is applied for a period of time until the fuse temperature stabilizes.
The power dissipated by the fuse is measured.
The heating of components is measured.
This ensures that the fuse does not thermally degrade in continuous use.
3. Time-current characteristic verification
Different currents are applied, causing the fuse elements to melt.
The time until the fuse interrupts the circuit is measured.
4. Striker pin test
A current is applied that causes the fuse to blow.
The energy and reaction time of the striker pin are verified.
After passing all tests, the fuse can be certified by accredited testing laboratories.
Certification confirms that the product complies with European and international standards.
At CNC LTD, every production batch is accompanied by a certificate of conformity and signed quality control.
CNC LTD collaborates with accredited external laboratories — ICMET Craiova and CESI Berlin.
In parallel, every fuse produced is individually tested in our own factory for continuity and appearance.
Rigorous testing is not optional — it is the guarantee that a fuse-link will fulfill its duty when it matters most.
CNC LTD is a Romanian manufacturer of medium-voltage fuses, offering ISO-certified quality and proven reliability for energy utility companies worldwide.
