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Improving Efficiency and Safety in HV Circuit Breaker Testing: How Should India Embrace Best Developed Practice Improving Efficiency and Safety in HV
Circuit Breaker Testing: How Should India
Embrace Best Developed Practice?

Linus Claesson
GE Energy, Sweden

Adam Middleton
GE Energy, United Kingdom

Chandan Guha
GE Energy, India


Abstract
The Indian electrical power network is in a major phase of change with substantial growth and
asset development planned over the next 30-40 years.

Electricity deregulation changes the business environment for utilities, switchgear owners and
service companies. Deregulation has shown to lead directly to increased emphasis on efficiency
of operations, maintenance and service levels all of which impact network technical activities.
International experience in the domain of substation circuit breaker diagnostic test has shown
demands for shorter time periods for testing, whilst the switchgear is less and less available to be
taken out of service.

Many of these drivers are not new to private network operators (e.g. in heavy industries) where
overall plant operation is directly linked to reliable availability of critical power supplies.

In the Indian context, utilities and industries may not be facing the same problems of reducing
availability of expert technical staff to undertake testing of critical switchgear assets. However,
Indias rapid economic growth and increasing visibility within the International community
means that there will be greater pressure for reliable electricity supplies at the same time as
efficient development of critical grid assets. Also, the Indian network operators need to maintain
and develop the industry safety record.

Whilst concerns have been raised in the Industry on all of these business drivers, there are new
technical solutions that will provide Indian network operators with better, faster and higher
accuracy circuit breaker testing regimes. At the same time, such new techniques will allow test
engineers to complete their work in a safer environment, significantly improve their management
and presentation of test records, together with improved results traceability thereby providing
additional value to network operators.

The authors will present a review of international best practices in the testing of HV circuit
breakers and will explain why such new test techniques are very relevant to the forthcoming
growth in investment and development of the Indian electricity grid.

1 Introduction
Network Operators in India, as elsewhere, are faced with the expectation of stakeholders
(customers, regulator, government) that they will be able to continue to do more, with less.
Unlike many other network operators, India continues to expand its networks to reach those who
have not previously been connected to the network and continues to reinforce its networks to
provide sufficient capacity to meet the increasing industrial and commercial demands.

There will be significant emphasis upon investment into the core transmission and distribution
(T&D) infrastructure in India for the foreseeable future. As a consequence, the testing and
commissioning of high voltage circuit breakers will be a critical component in the overall growth
plan. In parallel, Indias plans to push forward with electricity network deregulation will increase
emphasis upon efficiency and effectiveness of both Capital and Revenue expenditures.

India has a major opportunity to benefit from new techniques and technology developed and
applied in other leading Industrial nations that have been proven to be adapted to the post-
deregulation business environment. Further, they will allow India to take full advantage of the
business benefits associated with increased safety for personnel involved in high voltage
switchgear testing. In complement, the application of new techniques in substation data
management will give India every opportunity to manage its network development in a safe and
orderly fashion.

Network Development and Deregulation: Issues for Indian Utilities
Faced with huge increases in demand and improvements in quality and reliability of supply to
support the nations economic growth, network owners and operators are taking every
opportunity to become more efficient and effective. International experience of electricity
industry deregulation has been seen to lead to change in the business environment for utilities,
switchgear owners and service companies. Deregulation has been shown to lead directly to
increased emphasis on efficiency of operations, maintenance and service levels all of which
impact network technical activities. International experience in the domain of substation circuit
breaker diagnostic test [4] reveals demands for shorter time periods for testing, particularly
because higher utilisation factors will mean that the switchgear is less often available to be taken
out of service.

In the Indian context, utilities and industries may not yet face the same problems of reducing
availability of expert technical staff to undertake testing of critical switchgear assets as is seen in
other leading industrial nations with the impending retirement of the Post War Baby Boom
generation. However, Indias rapid economic growth and increasing visibility within the
International community means that there will be greater pressure for reliable electricity supplies,
at the same time as efficient development of critical grid assets.

Internationalisation of business brings new challenges: substantial investments by global
corporations will bring with them new requirements for increased emphasis on Health, Safety and
Environmental compliance. It is therefore apparent that the Indian network operators, industrial
companies and contractors alike will need to establish and develop industry safety programs and
records more aligned to International best practice.

2 A review of current practice with recommendations for changes

Test preparation
Preparation for high voltage circuit breaker (HV CB) testing involves the safe isolation of
previously energised high voltage equipment. Earths are then applied to the isolated equipment,
although present practice sometimes requires the omission of one earth to enable correct
operation of the test equipment. See Figure 1, below.

Figure 1. There is a capacitive connection between live lines close by the test object. A constant current
generator is formed with current strengths of double-digit mA. This is a threat to people and is causing
interference in the test system if not handled with care. Earthing both sides of the test object will lead the
induced current to earth and provide a safer and more secure area for the test engineer.
Electrocution accidents in substation are mainly due to flashover from fault currents, lightning
strikes on power line connected to the substation and capacitive coupling within the substation.
Such incidents are often fatal. In conventional high voltage circuit breaker testing, this risk
appears because testing is performed after the removal of safety earthing.

Visibility of a good safety record within the International community, as well as among local
customers, is becoming a crucial asset in attracting investors and customers. Figure 1 illustrates
why it is important to create a safe area by earthing both sides of the test object and keep it
earthed throughout the test.

International regulations and country specific laws require all test objects to be earthed on both
sides before any maintenance work is performed on the object. Exceptions for this safety
prerequisite are common, but not supported, since conventional circuit breaker technology is not
functional with both sides earthed.

The most important test for circuit breaker diagnosis is main contact timing. Conventional
instrumentation technology requires the safety earthing to be removed during the test and is,
therefore, strictly not in compliance with substation safety procedures produced by eminent
International bodies, including the IEEE and IEC. National Safety agencies, including the UKs
HSE and USAs OSHA, and their counterparts in other countries, have issued guidelines prescribing
that circuit breakers need to be earthed at both ends during any maintenance work [1], [2].

3 Conventional timing with one side earthed requires special safety procedures. In many leading
industrial nations, a Senior Authorised Person (SAP) will be required during the test, see Figure
2. This means that testing will take longer, with the test equipment, test engineer and, most
importantly, the circuit breaker out of service for a longer time. Out of a typical working day, the
safety administration commonly requires up to four hours of additional standby/out-of-service
time. Typically, there is also an increase in the training/education level required for SAP over
Authorised Person status.

If the safety earthing were not removed, the dangerous voltage would be kept at a safe distance
from all personnel throughout the circuit breaker timing test. A safe area around the circuit
breaker is created and can be clearly marked with security fencing in accordance with
recommendations. The risk of accidents with arc flash and electrocution