Free Phone: 0800 485 990 (NZ)

News

Find out about SFRA the practical way!

Tony Wills - Application engineer

Sweep frequency response analysis (SFRA) testing on transformers provides invaluable information about the mechanical integrity of the transformer’s components – information that can’t be obtained in any other way without dismantling the transformer or at the very least, by performing a thorough internal inspection. Mechanical movement or deformations within the transformer produce changes in the transformer’s inductance and capacitance distribution. It is these changes that SFRA testing measures.

Some engineers and technicians however, find SFRA test results daunting to analyse, particularly if they have not had much experience with using this technique. Having comparative results, ideally from tests performed when the transformer was new or in known good condition, is a big help, because SFRA test results should not change throughout the life of a transformer. But when changes in the test results are seen, what do they signify? International standards organisations have developed guides and brochures to help answer this question but for those who prefer a more practical hands-on approach, Megger’s FDB101 demonstration tool is a very attractive alternative.

Read more ...

Circuit breaker and transducers - part 2

Part 1 of this article, which appeared in the September's 2017 edition of Electrical Tester online and is available by clicking here, looked at the basics of time and travel measurements for circuit breakers. This second and final part presents a practical case study, and also discusses how to proceed when the circuit breaker manufacturer provides little or no information to aid time and travel measurement.

Robert Foster - Application engineer 

Case study: Siemens SPS2-38-40-2 Circuit Breaker

Read more ...

Centrix takes cable test to the heart of the city

Compact City TanDelta onsit

Centrix City and Centrix City Compact vans are equipped with the latest generation of non-destructive cable diagnostic systems. These include an SPG 40 test set, which is a multi-functional system for testing, prelocation, pinpointing and burning of cable faults in low and medium voltage networks.

In the City van, this is partnered with an Teleflex T 30-E reflectometer, and all functions are easily managed from fully integrated control unit that provides testing, diagnostics and fault location on one screen. In the City Compact van, the SPG 40 test set is used in conjunction with a detachable Teleflex SX reflectometer to provide testing and fault location functionality. Diagnostic functions are provided via a laptop computer.

The systems in both vehicles have been designed to be easy to work with and they follow the Megger easyGO operating philosophy that enables even inexperienced users to efficiently carry out cable checks, fault location and diagnostics. Comprehensive safety features are also incorporated, with all safety-relevant parameters automatically monitored in line with current codes and standards.

The last resort

Standby battery installations provide electricity to key elements of power generation, transmission and distribution systems, such as circuit breakers and protective relays, computers, control panels and telecommunication equipment, when other power sources have failed. The batteries can provide power instantly, either directly as DC or via an inverter as AC, thereby ensuring that critical systems continue to operate until emergency generators are ready to take over, or the main electricity supply is restored.

Read more ...

Electrical safety when using test equipment

Introduction

Man SUNSETA great deal of attention is devoted to safe working practices relating to electrical construction, maintenance and repair work. Industry electrical publications regularly report on safety issues, including the use of the proper tools and equipment for energised and de-energised work, as well as using the correct personal protective equipment (PPE) for each workplace situation. However, electrical test instruments are given very little, if any, discussion in safety articles. Even the dangers of using the wrong test instrument or using an instrument improperly, which can have catastrophic results, are rarely mentioned. 

Some of the most frequently used test instruments include non-contact voltage testers, multimeters, insulation testers and ground-resistance testers. A big issue with using non-contact or proximity devices, for example, is that to prove a circuit is de-energised it is necessary for that circuit to be tested phase-to-phase and phase-to-ground, which cannot be done using this type of tester.

When electrical safety is discussed, the subjects of shock, arc flash, and arc blast predominate in the discussions. The question is often asked: How do I identify when these hazards are present, or likely to be present, when I am using electrical test instruments on electrical circuits and equipment? This article discusses electrical hazards, along with requirements for assessing the workplace to identify electrical hazards, and also discusses personal protective equipment (PPE) associated with using test instruments.

Read more ...

Transformer screening: Is it time for a rethink?

Winding resistance testing is a very revealing electrical diagnostic test for the routine screening of power transformers to determine their “state of health”. In fact, it’s an essential test when dissolved gas analysis indicates overheating in the oil or of the paper, and no condition assessment is complete without it.

Moreover, if you were to ask experienced substation maintenance engineers for their thoughts about which electrical tests should be done on a routine basis (which is not necessarily the same, of course, as the tests they are actually doing!), the winding resistance test would be likely to take second place only to the transformer turns ratio (TTR) test.

P1000645 transformerThe TTR test typically takes top honours, not necessarily because of its diagnostic capabilities, but because it provides validation and reassurance that the transformer is actually doing what it’s supposed to do - transforming voltage. Nevertheless, the DC winding resistance test would be a very strong contender for the top spot if the list of important transformer tests were ever re-ordered purely on the basis of diagnostic value and screening prowess.

Read more ...

Enjoy Training on the Megger Multi-function Tester in your own Home!

AVO  NZ launches web-based customer-only training for the Industry’s leading multi-function tester

  • Innovative NZ -developed course by AVO NZ
  • Exclusively offered to all Megger MFT1800 series owners
  • Learn at home, at your own pace…no training downtime!
  • Train all your staff for zero outlay!
  • Covers theory, tips & technique in loop & RCD testing
  • Clear, simple teaching format
  • Fully indexed content for targeted review
  • Perfect for training & practicing licence review!

Sign up now ...

This is huge $$$ value and only from AVO NZ!

 

AVO NZ - Apprentice Pricing Now Available

For over 80 years Megger instruments have been sold in New Zealand and led the industry for all it’s testing and application needs. AVO New Zealand is proud to continue this tradition and is supporting the next generation of electrical apprentices.

Apprentice-Pricing-discount

*Discount from trade price. Full name and EW number of apprentice to be supplied at time of order placement

Apprentice-Pricing