Retrofitting of Oil Circuit Breakers
Retrofitting old medium voltage switchgear with newer technology is an efficient, cost effective and economical option for preserving existing assets, thus, saving cost and time. In the race of implementation and adaptation of new technology we just destroy existing installation by scraping the products for want of alternate solutions and technologically sound and reliable supplier…
- Paresh Shah, N P Jhaveri
With Prime Minister’s call for Make in India, there is need for development and change in all sectors of industries. Electricity is the prime over of all industrial and commercial activity and needs to meet increasing demand rapidly. As such efficient generation, distribution, utilization of electricity and preservation and management of asset is of utmost importance. Infrastructure for electricity generation and distribution is capital intensive and has long gestation time. The expected life of capital equipment is 15 to 20 years. After that there is obsolescence in terms of technology and maintenance. With more and more IT enabled equipment obsolescence becomes even faster.
Major components in medium voltage switchgear are breaker, bus bars, insulating components and control and protection equipment. Insulating components like CT, PT, Insulators, molded contact shrouds have relatively less degradation and have long service life of around 30 years and over depending upon environment. Over the last three to four decades major technological changes have taken place in breaker and control and protection equipment. For breakers the technology has changed from MOCB to Vacuum Circuit Breaker and SF6 with SF6 fading out of switching applications in medium voltage. Control and protection equipment have undergone a sea change from electromechanical devices to IT enabled products.
Although it is not new concept retrofitting old medium voltage switchgear with newer technology is an efficient, cost effective and economical option for preserving existing assets, saving cost and time. In the race of implementation and adaptation of new technology, we just destroy existing installation by scraping the products for want of alternate solutions and technologically sound and reliable supplier.
We at Jyoti have supplied thousands of Medium Voltage Switchgear Products starting from 3.3 kV to 33kV system voltage to all sectors in India e.g. power generation, transmission and distribution network, oil, petrochemical, fertilizer etc. The MV switchgears supplied (both MOCB and VCB) are still in service after 20 to 25 years and requests are received regularly for retrofitting these installations. Such retrofitting further extends the life of installation at least by 10 to 15 years.
Following up gradation can be carried out in existing installations panels:
1. Replacement / Retrofitting of old oil circuit breaker with latest Vacuum Technology. (Fig 1, 2 and 4)
2. Providing new feature in existing panel such as closed door operation for the safety compliance as per latest IEC 62271 requirement. (Fig 5 )
3. Servicing and refurbishment of existing panel compartments like CT / Cable Compartment, Breaker Compartment, Bus bar Compartment and vermin proofing of panels. (Fig 3)
4. Upgrading the load capacity by increasing various bus bar sections of panels and change in rating of breaker which avoids requirement of new panel with higher rating. (Fig 3)
5. Replacement / Retrofitting of old electro-mechanical relay with latest Numerical Relay having IEC 61850 protocol protection system of nation's statutory requirement.
Figure 1: VCB MOCB
Figure 2: MOCB Truck Figure 3: Refurbishment
Figure 4: Cassette Mounted VCB
Figure 5: Retrofitted VCB
Utilities purchase medium voltage equipment for distribution network in large numbers. These MV switchgears are procured from different manufacturers by tendering. The MV switchgear of different manufacturers varies dimensionally and specially in bus bar configuration. This leads to a problem whenever new feeders or incoming sources are to be added to any sub station. The extension has to be done either by same make of switchgear or adapter panel is required to match bus bar of switchgear from two different vendors. The adapter panels usually is made by unqualified local vendors which may compromise safety. Further, it consumes precious floor space.
One of the most reputed utility of India had a wish to have switchgear with common bus bar and so invited various manufacturers on this topic. Jyoti conceptualized, proposed and engineered a common bus bar concept which was accepted by utility and various vendors to the utility. Switchgear with this concept has already been supplied and installed. In future other utilities may also implement such concept. This is in a way advance planning against future availability of a specific product from a particular vendor. The concept is illustrated above in Fig.6 and 7 .
Fig 7a:Common Busbar Concept Fig 7b:Rear View of Common Busbar Concept
In many ways, retrofitting is just like a save energy drive. Every unit saved is unit generated. It reduces requirement of new installation, new cabling as there is no need for removal of old installation. Renewable energy has reduced the load on conventional power plants and thereby, requirement of coal, gas, and oil. Similarly, retrofitting is conservation of national assets like steel, copper, resin, imported materials, items which can be employed more productively.
Government can encourage concept of retrofitting in private and public sector by giving incentive like for energy generation by renewable sources. Some examples of retrofitting are illustrated in the article.
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