Category Archives: Standards

A medium-voltage circuit breaker has one job that matters above all others: interrupt a fault current safely, on demand, possibly after sitting closed and untouched for years. Testing exists to prove it still can. But “circuit breaker testing” covers three completely different activities done by three different people in three different places — and most of the confusion… Read More: MV Circuit Breaker Testing: Type, Routine & Field Tests (IEC… »

A lightning strike on a transmission line lasts microseconds. A power transformer is designed to run for forty years. The lightning impulse test is the bridge between those two facts — it proves, in the factory, that the transformer can survive the microsecond event so it can deliver the four decades of service. The test applies a standardized… Read More: Lightning Impulse Testing for Power Transformers: Why It Works and… »

If you’ve been doing motor insulation testing for any length of time, you’ve heard the standard cited a hundred times. “IEEE 43 says the PI minimum is 2.0.” “IEEE 43 requires correction to 40°C.” Most techs and engineers work from the rules without ever opening the document. That works fine until it doesn’t. Until an auditor asks where… Read More: IEEE 43-2013 Explained: A Clause-by-Clause Guide to Motor Insulation Testing… »

A 132 kV underground cable runs eight kilometers between two substations. After installation, before energization, a single test must verify that the cable, terminations, and joints will hold off operating voltage reliably for the next 30+ years. Insulation resistance testing won’t detect the small voids in joint accessories. Hi-pot testing might catch gross defects but won’t see the… Read More: Cable Partial Discharge Testing per IEC 60840: Field Procedures and… »

Every time a motor starts across town, your power supply takes a hit. Every time a fault clears on the distribution grid, voltage drops for a few cycles. Every time the UPS swaps from mains to battery, there’s a transition. Most electronic equipment handles these disturbances without a hiccup. Some doesn’t. The difference is whether the equipment has… Read More: IEC 61000-4-11 & IEC 61000-4-29: Voltage Dip Immunity Testing Explained »

A protection relay doesn’t work without its auxiliary supply. The CT and VT measurements feed the analog inputs, but the processor, the display, the communications, and the trip contacts all run off the auxiliary voltage. In most of the world, that auxiliary voltage is 220V — either 220V DC from a substation battery or 220V AC from a… Read More: IEC Relay Test Standards for 220V Auxiliary Supply: What You… »

Insulation testing involves applying high voltage to equipment. The megger on your belt can output 500V, 1,000V, 2,500V, or even 10,000V DC. That’s enough to injure or kill. But the real danger often isn’t the megger itself — it’s the stored energy in the equipment you just tested. A long cable charged to 5,000V DC during a 10-minute… Read More: Safety Procedures for Insulation Testing: A Field Engineer’s Checklist »

Protection relays sit at the heart of every substation and industrial power system. They make life-or-death decisions in milliseconds — tripping breakers to isolate faults before equipment is destroyed or people are hurt. If the insulation inside a protection relay fails, the relay itself becomes the fault. And that can take out the protection for an entire feeder,… Read More: IEC 60255-5: Insulation Testing for Protection Relays Explained »

If you work with electrical equipment internationally, IEC standards govern how you test insulation. But the IEC catalog has dozens of standards that mention insulation testing — and figuring out which one applies to your equipment can be confusing. This guide cuts through the noise. I’ll cover the IEC standards you actually need for insulation testing, with the… Read More: IEC Insulation Testing Standards Explained: A Practical Guide »