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National Electric Energy Testing, Research & Applications Center
FAILURE ANALYSIS

Root Cause Analysis ... to ... Effective Solutions

WHY DO FAILURE ANALYSIS?

When a failure occurs, many questions arise:

  • Was the product properly designed?
  • Was it manufactured correctly?
  • Was the application correct?
  • Was it operated properly?
  • Was it maintained adequately?

While failures are undesirable, they can potentially generate a wealth of information. This information can provide answers to each of the questions listed above.

Products fail for many different reasons. Poor quality, misapplication and improper installation are the most common reasons.
The prevailing desire to reduce product cost has led manufacturers to produce products
that have little capacity to operate outside their design limits. Recent trends by utilities to reduce the size of their skilled workforce sometimes makes it difficult to assure that products are installed properly.

The key to finding the cause of failure is to conduct an accurate, thorough failure investigation. This will produce information that can be used to reduce or eliminate future occurrences. The information can also be used to address many of the other aspects of a a product failure, including legal issues. Manufacturers can use the results to improve designs or manufacturing processes. Utilities can use the results to improve application, installation and maintenance practices.

PILC
Cable Termination Failure

What was the cause:

  • Moisture intrusion caused by an aged rubber seal?
  • Dielectric fluid drained from cable insulation?
  • Stress cone improperly positioned?

HOW DO YOU DISTINGUISH THE CAUSE OF FAILURE?

X-ray of a Current Limiting Fuse Failure

Was it caused by:

  • a mild overload?
  • heat transferred from a poor terminal connection?
Surface tracking of an instrument transformer caused by UV degradation of the polyurethane insulation. Eventually, a flashover failure occurred.

A compression connector from within a cabled joint.

  • Was the connector installed correctly?
  • Correct die used?
  • Conductor wire brushed to remove oxides?
  • Is it the right connectior for the job?
  • Appropriate size for conductor?
  • Adequate ampacity capacity?

Knowing what to look for and how to interpret the observations requires experience and knowledge in many different fields.

FINDING THE ANSWER

Bus Cover from Metal-clad Switchgear

Was the discoloration caused by:

  • overheating?
  • chemical attack?

NEETRAC has the experience, expertise, and equipment to provide failure analysis services on a variety of products and devices. Our expertise extends from residential wiring through large power transformers in substations, from surge arresters on a transmission line to fuses on a secondary distribution circuit. With over 25 years of experience in failure analysis, NEETRAC has experts in electrical, mechanical, and thermal systems analysis capable of addressing a broad range of problems. How can we help you?

Step
Voltage Regulator Failure

Flashover
of a Polymer Insulator String Under the Skirts.

Last revised on October 27, 2011