What a Heat Run (Temperature-Rise) Test Proves and Why It Matters A heat run test—also called a temperature-rise test—verifies that equipment runs within safe thermal limits under rated or near-rated load for an extended time. You circulate a controlled current through the full primary path and monitor temperature rise at hot-spot locations. This exposes loose... Learn More

What a Directional Relay Does and Why It Matters Directional relays are not just overcurrent devices with extra logic. They compare current from CTs with voltage from PTs to determine the fault direction. That single capability is decisive in parallel feeders, ring networks, and multi-infeed grids, where faults may be fed from both sides. I... Learn More

Introduction The IEC 61850 protocol is an international standard designed for substation automation systems (SAS). It enables seamless communication between Intelligent Electronic Devices (IEDs), regardless of the manufacturer, providing interoperability and efficiency. Today, IEC 61850 is widely used in medium- and high-voltage substations and is gaining importance in renewable energy facilities like wind and solar... Learn More

Once a recloser logic failed on a 33kV line during a storm. First trip was good. Second trip was good. Then it tried to reclose into a still-faulted line — and didn’t lock out. You know what happened next. Recloser that did not operate properly And on the photo above you can see a result... Learn More

Relay vs. Circuit Breaker: Understanding Their Role in Protection Systems In substations and industrial power systems, relays and circuit breakers form the backbone of protection and control. But while both devices respond to abnormal electrical conditions, their functions are entirely different—and understanding that difference is critical for engineers in testing and maintenance. What is a... Learn More

Introduction At the heart of every substation lies a vital component: the protection relay. Though small, its role is huge — detecting faults and triggering disconnection before damage occurs. If it fails, the entire installation is at risk.  This is why relay testing is not just a maintenance task — it’s a critical safety measure. ... Learn More

1. Summary of the event On April 28th, 2025, Spain experienced a massive electrical blackout that affected the entire Iberian Peninsula, disrupting electricity supply across Spain and its interconnections with Portugal and France. According to Red Eléctrica de España (REE), the event was triggered by a sudden loss of 15 GW of generation within just... Learn More

Introduction In electrical distribution systems, low voltage (LV) switchgear plays a crucial role in controlling, protecting, and isolating electrical equipment. To ensure safety, reliability, and compliance with industry standards, regular switchgear testing is essential. This article outlines the key factors to consider when testing LV switchgear to maintain optimal performance and prevent failures. 1. Insulation... Learn More

Introduction Reclosers are essential components in modern power distribution systems. They function as automated circuit breakers designed to detect and interrupt faults, then automatically restore service if the fault clears. Reclosers significantly enhance grid reliability by reducing outage durations and minimizing service disruptions. These devices are commonly used in overhead distribution networks and substations, playing... Learn More