High current impact testing service

High Current Impact Testing Service – Accredited ISO/IEC 17025 Electrical Stress and Fault Current Performance Assessment for the Croatian Market

High current impact testing is a critical electrical evaluation method used to assess the ability of electrical components, systems, and materials to withstand sudden, high‑magnitude current surges, fault currents, short‑circuit stresses, and transient overloads without sustaining permanent damage, arc flash, or catastrophic failure. This testing is essential for ensuring the safety, reliability, and regulatory compliance of fuses, circuit breakers, contactors, relays, busbars, cables, connectors, power supplies, batteries, and automotive electrical systems. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Državni inspektorat, the Ministarstvo gospodarstva i održivog razvoja, the Hrvatska regulatorna agencija za mrežne djelatnosti (HAKOM), and the Carinska uprava enforce strict quality, safety, and performance standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of high current impact performance is essential for product certification, CE marking, supplier qualification, type testing, quality control in manufacturing, and import‑export processes. Our laboratory offers a comprehensive high current impact testing service, applying standardized methods such as IEC 60947, IEC 60269, IEC 60068‑2‑58, ISO 16750‑2, ASTM F1924, and HRN EN 60947 to measure short‑circuit withstand capacity, peak current, I²t energy, arc flash energy, and post‑test integrity under controlled high‑current conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Croatian authorities and notified bodies, making them indispensable for regulatory compliance, product validation, and market access in Croatia and the European Union.

Electrical Components and Systems We Regularly Test

Our laboratory receives a wide variety of electrical components, assemblies, and systems for high current impact testing. Typical samples include:

• Fuses and fuse holders – for low‑voltage and high‑voltage protection, including fast‑acting, time‑delay, and semiconductor fuses.
• Circuit breakers and motor protection devices – miniature circuit breakers (MCBs), moulded‑case circuit breakers (MCCBs), and residual current devices (RCDs).
• Contactors, relays, and switches – for power switching, motor control, and automation systems.
• Busbars and power distribution components – for switchgear, panel boards, and power distribution systems.
• Cables, wires, and connectors – for high‑current and high‑power applications.
• Automotive and electrical vehicle components – battery packs, power electronics, and high‑voltage wiring.
• Power supplies and battery systems – for UPS, energy storage, and industrial power.
• Prototype and new device designs – submitted by manufacturers for validation of high current impact resistance before series production.
• Field‑retrieved components – for failure analysis and remaining life assessment.

Short‑Circuit and Fault Current Testing – Evaluating the Withstand Capability

Short‑circuit and fault current testing is the most fundamental high current impact test. It evaluates the ability of a component or system to withstand a high‑magnitude fault current for a specified duration without sustaining damage that would compromise safety or functionality. Our tests follow international standards and the requirements of the Croatian electrical, automotive, and industrial sectors.

• Short‑circuit withstand test (IEC 60947‑2 / HRN EN 60947‑2 / NTC 5900 – for circuit breakers and switching devices) – we connect the test device to a high‑power source and apply a fault current of a specified magnitude (e.g., 10 kA, 25 kA, 50 kA, or 100 kA) for a specified duration (e.g., one to three cycles of 50 Hz). The test device is operated in the closed position, and the current and voltage are measured using a high‑precision data acquisition system. We measure the peak current, the RMS current, the duration of the fault, and the I²t energy (the integral of the current squared over time). After the test, the device is inspected for any damage (welding of contacts, deformation, or arc damage). We report the withstand current, the I²t energy, the duration, and the condition of the device (pass/fail).
• Short‑circuit current test for fuses (IEC 60269 / HRN EN 60269 / NTC 5901 – for low‑voltage fuses) – we apply a specified fault current to the fuse and measure the time to clear the fault (the melting time and the arcing time) and the peak let‑through current. The I²t characteristic of the fuse is determined. We report the clearing time, the peak let‑through current, the I²t energy, and the condition of the fuse.
• Fault current test for cables and connectors (IEC 60364 / NTC 5902 – for the thermal and mechanical withstand) – we apply a short‑circuit current of a specified magnitude (e.g., 5 kA, 10 kA) to the cable or connector and measure the temperature rise and the mechanical deformation. The cable is inspected for insulation damage or melting. We report the withstand current, the temperature rise, and the condition of the cable.
• Short‑circuit test at different power factors (NTC 5903 – for the asymmetric fault current) – we perform the short‑circuit test with different power factors (e.g., 0.1, 0.2, 0.5) to evaluate the effect of the asymmetrical fault current (the DC component) on the performance of the device. We report the peak current, the RMS current, and the asymmetry factor.
• Short‑circuit test with different fault currents (NTC 5904 – for the current‑dependence evaluation) – we perform the short‑circuit test at multiple fault current levels to construct the I²t curve and to determine the let‑through energy of the protection device. We report the I²t curve and the let‑through energy.

Surge Current and In‑Rush Current Testing – Evaluating the Transient Response

Surge current and in‑rush current testing evaluates the ability of a component to withstand the transient high currents that occur during start‑up, switching, or lightning strikes. These tests are essential for power supplies, capacitors, motor drives, and automotive electronics.

• Surge current test (IEC 61000‑4‑5 / NTC 5910 – for the lightning and switching surges) – we apply a defined surge current pulse (with a specified waveform, e.g., 8/20 μs or 10/350 μs) to the test device using a surge generator. The peak current and the waveform are measured. We report the peak surge current, the waveform, and the condition of the device.
• In‑rush current test (IEC 61000‑3‑3 / NTC 5911 – for the start‑up current) – we apply a rated voltage to the device and measure the initial current peak (the in‑rush current) at the moment of switching. The in‑rush current is recorded, and the device is inspected for any damage. We report the peak in‑rush current, the duration, and the condition of the device.
• Pulse current test (NTC 5912 – for the repetitive high‑current pulses) – we apply a specified number of high‑current pulses (e.g., 10, 100, or 1000 pulses) to the test device at a specified repetition rate (e.g., 1 Hz, 10 Hz). The device is inspected for contact erosion, welding, or degradation. We report the number of pulses, the peak current, and the condition of the device.
• Surge current test at different temperatures (NTC 5913 – for the thermal effect) – we perform the surge current test at elevated temperatures (e.g., 60 °C, 85 °C) to evaluate the effect of temperature on the surge current capability. We report the surge current capability at each temperature.
• Surge current test with different waveforms (NTC 5914 – for the waveform sensitivity) – we apply surge currents with different waveforms (e.g., 8/20 μs, 10/350 μs, 1.2/50 μs) to evaluate the sensitivity of the device to different transient types. We report the surge current capability for each waveform.

Arc Flash and Energy Dissipation Testing – Evaluating the Safety and Protection

Arc flash testing evaluates the ability of a component or system to contain and extinguish an electrical arc, and to limit the arc energy. This is critical for switchgear, circuit breakers, and other protection devices, and is required for safety certification in the Croatian and EU markets.

• Arc flash test (IEC 60947‑1 / IEEE 1584 / NTC 5920 – for the arc energy measurement) – we create a controlled arcing fault in the test device and measure the arc current, the arc voltage, and the duration of the arc. The arc energy (in J or cal/cm²) is calculated. We report the arc energy, the arc duration, and the condition of the device.
• Arc‑fault current limiting test (NTC 5921 – for the current‑limiting performance) – we apply a fault current to a current‑limiting device (e.g., a fuse or a current‑limiting circuit breaker) and measure the peak let‑through current and the I²t energy. The current‑limiting performance is evaluated. We report the peak let‑through current, the I²t energy, and the performance class.
• Short‑circuit protection coordination test (NTC 5922 – for the selectivity assessment) – we test a series of protective devices (e.g., a fuse and a circuit breaker) to verify the coordination and the selectivity (the ability of the downstream device to clear a fault before the upstream device trips). We report the coordination results and the selectivity rating.
• Arc flash boundary and incident energy measurement (NTC 5923 – for the safety distance) – we measure the incident energy (in cal/cm²) at different distances from the arc, and we determine the arc flash boundary (the distance at which the incident energy reaches 1.2 cal/cm²). We report the incident energy and the arc flash boundary.
• Arc‑flash test at different voltages (NTC 5924 – for the voltage effect) – we perform the arc‑flash test at different voltages (e.g., 230 V, 400 V, 690 V) to evaluate the effect of the voltage on the arc energy and the safety. We report the arc energy and the arc flash boundary at each voltage.

Thermal and Mechanical Stress under High Current – Evaluating the Structural Integrity

High current surges generate significant thermal and mechanical stresses (due to the magnetic forces). Our tests evaluate the effect of these stresses on the structural integrity and the performance of the component.

• Thermal stress test under high current (NTC 5930 – for the temperature rise and heat dissipation) – we apply a high current (e.g., 80 % of the rated current) to the test device for a specified duration (e.g., 1 hour, 2 hours) and measure the temperature rise at the critical locations (e.g., the terminals, the contacts, the housing). The temperature rise is measured using thermocouples or an infrared camera. We report the temperature rise (in °C) and the temperature distribution.
• Electrodynamic force test (NTC 5931 – for the magnetic forces) – we apply a high fault current to the busbar or the conductor and measure the mechanical deflection (the bending or the displacement) caused by the magnetic forces. The deflection is measured using a laser displacement sensor or a dial gauge. We report the deflection (in mm) and the stress level.
• Short‑circuit withstand test with mechanical stress (NTC 5932 – for the combined electrical and mechanical stress) – we apply a short‑circuit current to the test device while simultaneously applying a specified mechanical vibration or a shock load. The combined effect of the electrical and mechanical stress is evaluated. We report the withstand capability and the condition of the device.
• Thermal imaging during the high current test (NTC 5933 – for the hot‑spot detection) – we use an infrared camera to capture the thermal image of the test device during the high current test. The hot‑spots and the areas of excessive heating are identified. We report the thermal images and the hot‑spot locations.
• Post‑test electrical and mechanical inspection (NTC 5934 – for the integrity verification) – after the high current impact test, we perform a visual inspection, a continuity test, an insulation resistance test, and a mechanical operation test (for switching devices) to verify the integrity of the component. We report the inspection results and the pass/fail status.

Environmental and Aging Effects – Evaluating the Long‑Term High Current Performance

The high current impact resistance of components can change over time due to thermal aging, corrosion, and mechanical fatigue. Our environmental and aging tests evaluate the long‑term stability of the high current performance, ensuring the reliability of the product over its service life in the diverse Croatian climate (coastal, continental, and mountainous).

• Thermal aging and its effect on high current impact resistance (ASTM D573 / ISO 188 / NTC 5940 – for the heat‑aged components) – we age the component in an oven at a specified temperature (e.g., 70 °C, 100 °C) for a specified duration (e.g., 7, 14, or 28 days) and then perform the high current impact test. The change in the withstand current and the I²t energy is reported. We report the high current performance after aging and the retention of the performance.
• Salt spray and corrosion effect (ASTM B117 / NTC 5941 – for the corrosion‑exposed components) – we expose the component to a 5 % NaCl salt spray at 35 °C for a specified duration (e.g., 240, 500, or 1000 hours) and then perform the high current impact test. The effect of the corrosion on the high current performance is reported. We report the high current performance after salt spray and the corrosion rating.
• Humidity and moisture effect (ASTM D570 / NTC 5942 – for the moisture‑exposed components) – we condition the component at a high‑humidity environment (e.g., 40 °C, 95 % RH) for a specified duration (e.g., 7 days) and then perform the high current impact test. The effect of the moisture on the high current performance is reported. We report the high current performance after humidity exposure and the moisture uptake.
• Mechanical fatigue and vibration effect (NTC 5943 – for the mechanically stressed components) – we subject the component to a specified number of vibration cycles (or mechanical shock cycles) and then perform the high current impact test. The effect of the mechanical fatigue on the high current performance is reported. We report the high current performance after the mechanical stress and the fatigue rating.
• Chemical exposure effect (ASTM D543 / NTC 5944 – for the chemically exposed components) – we immerse the component in various chemicals (e.g., mineral oil, acids, bases, or solvents) for a specified duration and then perform the high current impact test. The effect of the chemical exposure on the high current performance is reported. We report the high current performance after chemical exposure and the compatibility.

Complementary Tests – Contact Resistance, Insulation, and Material Characterization

To fully understand the high current impact performance and to correlate it with the material properties and the contact integrity, we perform complementary tests, including contact resistance measurement, insulation resistance testing, and material characterization.

• Contact resistance measurement (ASTM B539 / NTC 5950 – for the contact integrity) – we measure the contact resistance (in μΩ or mΩ) of the switching device (e.g., a contactor or a circuit breaker) before and after the high current impact test. An increase in the contact resistance indicates contact degradation. We report the contact resistance before and after the test and the change.
• Insulation resistance and dielectric strength (ASTM D257 / NTC 5951 – for the insulation integrity) – we measure the insulation resistance (in MΩ or GΩ) and the dielectric strength (in kV) of the component before and after the high current impact test. The loss of insulation integrity indicates damage. We report the insulation resistance and the dielectric strength before and after the test and the change.
• Hardness testing (ASTM E18 / NTC 5952 – for the contact material) – we measure the hardness (Rockwell, Brinell, or Vickers) of the contact material before and after the test. The change in hardness indicates the softening or the hardening of the material. We report the hardness before and after the test and the change.
• Metallographic examination (ASTM E3 / NTC 5953 – for the microstructure changes) – we examine the microstructure of the contact material (the grain size, the phase distribution, and the presence of arcing damage) using optical microscopy and SEM. The microstructure changes are correlated with the high current performance. We report the SEM images and the microstructural changes.
• Chemical composition analysis (XRF, EDS – NTC 5954 – for the material verification) – we use X‑ray fluorescence (XRF) or energy‑dispersive spectroscopy (EDS) to verify the chemical composition of the material. The composition is correlated with the high current performance. We report the composition and the compliance with the specified grade.

Test Report and Recognition in the Croatian Electrical, Automotive, and Energy Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (high‑power sources, surge generators, oscilloscopes, and data acquisition systems) and traceability to international standards (NIST, PTB). Our test reports are issued in English (with a Croatian summary available on request) and include:

• Full identification of the test component (manufacturer, model, rated current, voltage, and protection class).
• Detailed description of the test methods applied (IEC/ISO/HRN EN/NTC standards, test conditions, fault current, and duration).
• Numerical results: withstand current (kA), peak current (kA), I²t energy (A²s), arc energy (J or cal/cm²), temperature rise (°C), contact resistance (μΩ), insulation resistance (MΩ), and property retention after aging (%).
• Graphical data: current vs. time curves, I²t curves, and temperature vs. time curves.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (IEC 60947, IEC 60269, HRN EN 60947, and the requirements of the HZN, HAKOM, and Državni inspektorat).
• Statement of compliance and pass/fail status.
• Photographs of the component before and after the test, and SEM images of the contacts.
• Recommendations for material selection, design optimization, and quality control measures to achieve the required high current impact performance.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98‑3 Guide.

These reports are fully accepted by the Hrvatski zavod za norme (HZN) for the verification of product conformity, by the Ministarstvo gospodarstva i održivog razvoja for industrial and energy compliance, by the Državni inspektorat for market surveillance, by the Hrvatska regulatorna agencija za mrežne djelatnosti (HAKOM) for electrical and telecommunications equipment, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of electrical and electronic components. Additionally, we offer consulting services for the selection of high‑current components, the design of robust protection systems, and the implementation of quality control programs for high current impact performance, contributing to the safety, reliability, and performance of electrical and electronic products in the diverse and growing Croatian market, from the power generation and distribution sectors to the automotive, aerospace, and industrial machinery industries.