Zakaria El Intissar

Zakaria El Intissar is an automation and industrial computing engineer with 12+ years of experience in power system automation, electrical protection, and SCADA systems. He founded InsulationTesting.com to share practical, field-tested guides on insulation resistance testing, equipment, and industry standards. His writing is used by electricians and maintenance engineers worldwide. Based in Morocco.

Author Archives: Zakaria El Intissar

IEC 60255-5: Insulation Testing for Protection Relays Explained

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 »

Transformer Insulation Testing: Complete Guide to Methods, Standards, and Field Procedures

Transformer insulation is the single most critical component determining the life and reliability of a power transformer. Over 60% of transformer failures are linked to insulation breakdown. Once it fails, you’re looking at months of downtime and repair costs that can reach hundreds of thousands of dollars. The good news: insulation problems don’t happen overnight. They develop over… Read More: Transformer Insulation Testing: Complete Guide to Methods, Standards, and Field… »

IEC Insulation Testing Standards Explained: A Practical Guide

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 »

Polarization Index Test: What It Is, How to Do It, and What the Results Mean

The polarization index test is the most reliable way to assess insulation condition on motors, generators, and other rotating machinery. It goes deeper than a standard 60-second megger reading and gives you a result that’s independent of temperature and equipment size. If you only have time for one insulation test on a critical motor, make it the PI… Read More: Polarization Index Test: What It Is, How to Do It,… »

Megger vs Hi-Pot: What’s the Difference?

Megger testing and hi-pot testing both involve applying high voltage to insulation. Both measure how current behaves through that insulation. And both help you find problems before they cause failures. But they’re not the same test. They serve different purposes, use different voltage levels, and are used at different stages of an equipment’s life. Mixing them up —… Read More: Megger vs Hi-Pot: What’s the Difference? »

Insulation Resistance Testing: The Complete Guide

Every wire, motor, transformer, and cable in your facility is wrapped in insulation. That insulation is the only thing standing between normal operation and a ground fault, a fire, or a serious injury. Insulation resistance testing tells you if that barrier is still doing its job. It’s simple, non-destructive, and takes minutes. Yet it’s one of the most… Read More: Insulation Resistance Testing: The Complete Guide »

How to Megger a Motor: Steps, Voltages, and Good Readings

A megger test on a motor takes about five minutes. Reading the result correctly takes a bit more than that. The number on the display means nothing on its own. A 50 MΩ reading is fine on a 6.6 kV machine and a warning sign on a 400 V one. Temperature moves it. Humidity moves it. A dirty… Read More: How to Megger a Motor: Steps, Voltages, and Good Readings »