Minimum Oil Circuit Breaker

These types of circuit breakers also utilize oil (transformer oil) as an interrupting medium. Unlike bulk oil circuit breakers, these designs place the interrupting units in insulating chambers at the live potential. This feature of the design of MOCBs reduces the requirement of oil and these breakers are therefore known as minimum oil circuit breakers. These I designs are available in voltages ranging from 1000 V to 765 kV using the multi-break technique. A typical view of 36 kV MOCB indicating the main parts is shown in figure 4.24.

This type of breaker is Widely used in transmission and distribution networks. In an oil circuit breaker, they are drawn across the contacts are contained inside the interrupting pot and thus the hydrogen bubble, formed by the vaporized Oil (gas) is also contained inside the chamber. As the contacts continue to move and When the moving contact rod separates itself from the orifice at the bottom of the chamber, an exit similar to a nozzle becomes available for exhausting the hydrogen that is trapped inside the interrupting chamber

It is well-known that minimum oil circuit breakers are sensitive to high TRV peak and prone to restrikes during switching capacitor banks. However, this problem has been effectively countered by pressurizing the interrupter heads with dry nitrogen.

These types of breakers were found to be more suitable for applications in countries with very low ambient temperatures like Canada, Russia, and Finland, where the gas blast circuit breakers become more sensitive to icing and liquefaction problems.

Due to their cross blast designs, minimum oil HV circuit breakers suffer from a few major inherent problems such as sensitivity to high peak voltage and the effects of pre-arcing. Usually, the out of phase switching test is the most difficult, test on MOCBs, which generally dictates the number of interrupters to be used in series for a particular voltage class. The energy released due to pre-arcing is very high and high strength insulating materials are required to enable cross jet pots and jet plates to “withstand high-pressure surges. The number of breaks per pole also depends upon the ability‘of the arc interrupting chamber to withstand the energy released due to PRC-arcing, which is a function of current in the arc and voltage per break.

Presently this technology is considered outdated due to the advent of VCB technology medium voltage and SF6 technology m the high voltage range.

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Limitations of Terzaghi Theory

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Comparison between VSI and CSI

Comparison between VSI and CSI In power electronic systems, inverters are an essential component that converts direct current (DC) into alternating current (AC). There are two main types of inverters used in power electronic systems: Voltage Source Inverters (VSI) and Current Source Inverters (CSI). Both have their own unique advantages and disadvantages, and the choice of which to use depends on the specific application and the desired outcome. Comparisons between voltage source inverters and current source inverters are as follows. In voltage source inverters, the input voltage is maintained constant and the amplitude of the output voltage does not depend on the load. However, the waveform of load current, as well as its magnitude, depends upon the nature of load impedance. In current source inverters (CSI), the input current is constant but adjustable. The amplitude of output current from CSI is freelance of the load. However, the magnitude of output voltage and its undulation outp

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