Protecting Wind Towers from Lightning
The Background: Our customer is an independent power producer that maintains a number of small windfarms and seeks a reliable means of testing that each windmill is protected from lightning strikes.
The Problem: Due to their size and the materials from which they’re made, windmills are highly susceptible to lightning strikes. Lightning is, in fact, the leading cause of downtime and catastrophic damage can occur if there’s not a good path from blade tips to the ground.
Due to the large distance between blade tips and ground as well as potential damage to conductors from blade flex, there isn’t an easy way to make sure that lightning travels through the lightning protection system rather than into the sensitive electronics.
Necessary periodic testing of the lightning protection system requires extra-long, high integrity test leads, but even the best leads with such length have such high resistance that they need to be used in conjunction with a high wattage, low-resistance ohmmeter.
The Solution: We recommended the Megger DLRO10HDX micro-ohmmeter which provides 25W of power which can supply the required 1A test current over the large distances required by this application and which can test in accordance with IEC61400-24 standards for low-resistance ohmmeters.
The DLRO10HDX was paired with Megger KC series leads which have been developed with turbine manufactures to create a Megger system solution. The leads are designed to test from blade tip to root of a grounding system and are fitted to a reel for ease of use.
Earth test connections to ground should also be completed to make sure complete system resistance is within appropriate guidelines.
