Maintenance of power circuit breakers internet version of this manual created december 1999 hydroelectric research and technical services group the appearance of the internet version of this manual may differ from the original, but the contents do not united states department of the interior bureau of reclamation. The legendary cg make bulk oil circuit breaker bocb was a highly reliable product with world wide installations. In oil circuit breaker the fixed contact and moving contact are immerged inside the insulating. Oil circuit breaker electric arc insulator electricity.
The construction is simple and it consists of fixed and moving contacts enclosed in a strong weather tight earthed tank containing oil up to a certain level and an air cushion above the oil. As regards quenching the arc, the oil behaves identically in bulk as well as low oil circuit breaker. The contacts are opened under oil and an arc is struck between them. After the circuit breaker has been disconnected from the. Also, the preferred technology is dependent on the geographical region in which it is applied. The quantity of oil requires in bulk oil circuit breaker. Although the use of oil breaker has reduced very much one can still find oil cb in many installations.
Oil circuit breakers pf test free download as powerpoint presentation. This activates the circuit breaker opening mechanism, making the circuit breaker open. Case in point, dead tank sf6 filled circuit breakers and bulk oil circuit breakers. A circuit breaker is a protective device which can break the circuit automatically under the fault condition. Such type of circuit breaker is also known as dead tanktype circuit breaker because their tank is held at ground potential. Bulk oil circuit breaker or bocb is such types of circuit breakers where oil is used as arc quenching media as well as insulating media between current carrying contacts and earthed parts of the breaker. Aug 09, 2018 the circuit breaker should be operated electrically from local and remote then mechanically from local. Even if the breaker contacts are immersed in oil, arcing still occur during. Bulk oil and minimum oil circuit breaker bulk oil circuit breaker. On the other hand, low oil circuit breaker only uses less oil compared to the bulk oil. Oil circuit breaker shipping the types f11 and f22 oil circuit breakers are built on the unit basis, i.
However, unlike bulk oil circuit breaker, a minimum oil circuit breaker places the interrupting unit in insulating chamber at live potential. Rated short circuit breaking current 40 ka rated shorttime current up to 3 s 40 ka leakage rate per year circuit breaker spring. The heat of the arc evaporates the surrounding oil and dissociates it into a substantial volume of gaseous hydrogen at high pressure. Accident experience has proven that the majority of switchgear failures occur during or shortly after an operation. Transmission and distribution oil circuit breaker retro. Bulk oil circuit breakers bocb bulk oil circuit breaker or bocb is a such type of the circuit breakers where oil is used as arc quenching media as well as insulating media between current carrying contacts and earthed parts of the breaker. Oil circuit breaker diagram types of oil circuit breaker. This isolates the faulty part from rest of the healthy system. An oil circuit breaker is a component of power supply that works closely with oil circuit recloser equipment to ensure the safe operation of the entire electrical system. The main components of an oil circuit breaker and how does it. Bulk oil circuit breaker construction of bulk oil circuit breaker. If the timing of the cb is too slow, it will fail to protect the equipment it is assigned to guard. Here arc energy is used to crack the oil molecules, hydrogen gas may be generated which can be used to sweep, cool and compress the arc plasma and so deionize it in a selfextinguishing process. This allows short current spikes such as are produced when a motor or other nonresistive load is switched on.
The importance of maintaining oil circuit breakers and all. Application, advantages and disadvantages of all types of. Whenever there is a separation of current carrying contacts in the oil, the arc in circuit breaker is initialized at the moment of separation of contacts. The oil circuit breaker is the one of the oldest type of circuit breakers. Performance examination of the bulk oil circuit breaker that is influenced by its parameters at the substation of bogor baru the state electricity company pln has been done. One is bulk oil circuit breaker bocb and the other type is minimum oil circuit breaker. The thermal portion of the circuit breaker provides a time response feature, that trips the circuit breaker sooner for larger over currents but allows smaller overloads to persist for a longer time. Apr, 2017 oil circuit breakerclassification of circuit breakers 1. Bulk oil circuit breakers are primarily used in north america in hv applications, while the rest of the. Westinghouse types gob, golb and go2b oil circuitbreakers fig. A dielectric failure to tank was reported on a westinghouse 345kv, type gw oil circuit breaker late in december 1968. Retrofitting solutions for brush bulkoil vsi type circuit.
Figure 1 shows the catastrophic nature of an oil circuit breaker failure with figure 2 showing an sf6vacuum circuit breaker failure for comparison. In this article the different types of circuit breakers, i. Exhaust the pressure from air receiver of any compressed air circuit breaker before it is inspected or re paired. Midwest has a huge stock of used, reconditioned and new oil circuit breakers. These circuit breakers employ the high resistance interruption principle. Oil circuit breakers electric arc series and parallel. Bulk oil circuit breaker free download as word doc. Whenever there is a separation of current carrying contacts in the oil, the arc is initialized at the moment of separation of contacts, and due to this arc the oil. Oil circuit breaker construction working principle. And their subdivision is also discussed along with advantages and disadvantages.
The use of the wellproven vd4 type circuit breaker allows the. It is also known as minimum oil circuit breaker or live tank circuit breaker. The construction of plain break oil circuit breaker is very simple. This breaker makes use of oil for quenching the arc. A low oil circuit breaker employs solid materials for insulation purposes and uses a small quantity of oil which is just sufficient for arc extinction. Mineral oil has better insulating property than air. The hydrogen is used to sweep, cool, and compress the arc plasma. Due to decomposition of oil in the arc, the carbon particles is generated which polluted the oil and hence the dielectric strength of the oil. The contractor shall fully inform themselves of the details of the existing switchgear cubicles and circuit breakers and confirm that the replacement circuit breakers.
The importance of maintaining oil circuit breakers and all oil circuit recloser equipment february 16, 2017 2. Abb vacuum retrofitting circuit breakers allow the bulk oil based apparatus to be removed, thereby eliminating the fire hazard. The oil used here is same as transformer insulating oil. Bulk oil circuit breakers, once the mainstay of distribution system short circuit protection are now no longer used, having been replaced by, primarily, vacuum cbs. They assure that the cb is operating within the correct parameters to clear a fault. Inspection of the switching contacts which are in mint condition.
Such type of circuit breaker is also known as dead tanktype. Bulk oil circuit breakers electrical engineering 123. The minimum oil breakers were developed to reduce the oil. Circuit breaker introduction and operating principle ece. Oil circuit breaker oil cbs are extensively employed in our power systems. For bulk oil circuit breaker, we should check contact burning. It consists of current carrying contacts enclosed in a strong, weathertight earth metal tank and the tank is filled with transformer oil. These types of circuit breakers utilize oil as the interrupting media. We offer these oil circuit breakers at most affordable prices to our precious customers. The insulating oil is available only in interrupting chamber. There is no special system for arc control other than the increase in length caused by the separation of contacts. Ac highvoltage circuit breakers everything you wanted to know about ac highvoltage circuit breakers but were afraid to ask ieee switchgear committee portland maine, usa, october 2017.
The main components of an oil circuit breaker and how does. The quantity of oil requires in bulk oil circuit breaker depends on the system voltage. In an oil circuit breaker or ocb, the separating contacts of the breaker are made to separate within an insulating oil because insulating oil has better insulating properties than air. This process is generally known as retrofit and, because only the circuit breaker. It is pneumatically tripfree on automatic operation and mechanically tripfree on hand closing. Apr 16, 2017 they were used 5070 years ago in high voltage. The oil used here is same as transformer insulating oil minimum oil circuit breaker or mocb.
The circuit breaker can make or break the circuit either manually or by remote control. Figure 2 shows various contact travel curves during the opening of a circuit breaker 4. Thus the trip coil of a circuit breaker gets energized. Circuit breaker technology varies depending on the application. The hydrogen gas occupies a volume about one thousand times that of the oil decomposed. For insulation purposes, different insulating materials like porcelain, bakelised paper, glassfiber etc. In addition to its use as the arc extinguishing media, the oil serves as the insulating media between currentcarrying contacts and grounded parts of the breaker. Figure 4a 66 kv oil circuit breaker figure 4b bulk oil. Low minimum oil circuit breaker your electrical guide. The circuit breaker should be operated electrically from local and remote then mechanically from local. The usual application for this mechanism is for highspeed reclosing duty, but it is some.
Transmission and distribution circuit breaker maintenance in. Hi friends, in this article, i am going to describe the oil circuit breakers construction and working principle. Oil circuit breakers ocb can be categorised into two types. An oil circuit breaker operated by the type cas6 operating mechanism is closed by compressed air and opened by springs. Boa breaker oil analysis oil circuit breaker sample data. Pdf performance examination of the bulk oil circuit breaker that is influenced by its parameters at the substation of bogor baru the state. Bulk oil circuit breaker electric arc vacuum scribd. Principal electrical engineer tennessee valley authority senior member, ieee.
This type of operation makes the breaker more reliable by removing any coating developed between sliding surfaces. Bulk oil circuit breaker consumes a large amount of oil. Under normal operating conditions the fixed and moving contacts remains closed and breaker carries the normal circuit current. Circuit breaker lubrication in the field the majority of all circuit breaker failures below 38 kv are avoidable with proper lubrication. A highvoltage circuit breaker in which the arc is drawn in oil to dissipate the heat and extinguish the arc. Be sure the circuit breaker and its mechanism are disconnected from all electric power, both high voltage and control voltage, before it is inspected or repaired. This deionizes the arc plasma in a selfextinguishing process. Different types of circuit breakers and its applications. Medium voltage service technical flyer retrofit solutions for. Oil circuit breaker oil circuit breaker is such type of circuit breaker which used oil as a dielectric or insulating medium for arc extinction. In oil circuit breaker the fixed contact and moving contact are immerged inside the insulating oil. This becomes more evident when the associated costs of civil works. Low oil circuit breaker, mocb circuit breaker, minimum oil circuit breakers, minimum oil cb, pdf.
New oil inserted metering and protection current transformers in rear of panel. In a minimum oil circuit breaker very small quantity of insulating oil is used in arc extinguishing chamber. Retrofitting solutions for brush bulk oil vsi type circuit breakers circuit breaker retrofit is a costeffective alternative to a complete switchgear replacement. Each of those tanks has about 2500 gallons of mineral oil.
Bulk oil circuit breaker bocb in the bocb, oil is used to arc the quenching media and also for insulating media in between earth parts of circuit breaker and current carrying contacts. Case in point, dead tank sf6 filled circuit breakers and. Due to smaller quantity of oil, the degree of carbonisation is increased. Oil circuit breakers types, working and construction. Oil circuit breaker article about oil circuit breaker by. Technical paper a systematic approach to highvoltage. The circuit breaker which uses more oil or which is bulky is called bulk oil circuit breaker. Performance of bulk oil circuit breaker aip publishing.
Both are widely applied with the former being traditionally used in the usa and the uk and the latter in continental europe. Classification of circuit breakers oil circuit breakers plain break oil circuit breakers arc control oil circuit breakers low oil circuit breakers airblast circuit breakers types of air blast circuit breakers sulphur hexafluoride sf6 circuit breakers vacuum circuit breakers vcb. Find details of companies offering oil circuit breaker at best price. So i liked to write a little about oil circuit breaker in one article. Designed by using top notch technology and high grade raw materials that imparts it the superior performance and maximum working life. Pdf performance of bulk oil circuit breaker bocb influenced by. Bulk oil circuit breakers use a large quantity of oil while low oil circuit breakers use the minimum amount of oil. Instruction book oil circuit breaker types f11 and f22. So, it is called as an arc extinction chamber or current interruption chamber of minimum oil circuit breaker mocb. This switch is used with almost all westinghousetype aa mechanisms. Nov 21, 2015 oil circuit breakers in oil circuit breakers, the arc energy is used to crack the oil molecules to generate hydrogen gas. A systematic approach to highvoltage circuit breaker. Suitable for both manual and automatic operation 1. Oil circuit breaker bulk and minimum oil circuit breaker.
Circuit breaker is a device which makes the circuit when the operator intends it and which breaks the circuit based on operator intention as well as for any fault in the circuit. B oil is used for arc extinction all parts of this c. A breaker which uses a large quantity of oil for arc extinction is called a bulk oil circuit breaker. The quantity of oil requires for arc extinction is only about onetenth of the total and the rest being used for the insulation. The oil used in oil circuit breaker is inflammable and hence, cause a fire hazard.
Our clients can avail from us a wide array of oil circuit breakers. The main components of an oil circuit breaker and how does it interrupt the arc this is a 230,000 volt circuit breaker. Bulk oil circuit breakers often use oil or resinimpregnatedpaper capacitivegraded bushings that are equipped with tap electrodes and have cts mounted on the lower ground sleeve. In oil circuit breaker the contacts of the breaker are made to separate within an insulating oil. Oil circuit breaker bulk and minimum oil circuit breaker electrical4u. A plainbreak oil circuit breaker is a bulk oil circuit breaker which involves the simple process of separating the contacts under the whole of the oil in the tank. There is a risk of formation of explosive mixture with air. The features of designing mocb is to reduce requirement of oil, and hence these breaker are called minimum oil circuit breaker.
Bulk oil circuit breaker bulk oil circuit breaker or bocb is such types of circuit breakers where oil is used as arc quenching media as well as insulating media between current carrying contacts and earthed parts of the breaker. Air circuit breaker, sf6 circuit breaker, vacuum circuit breaker and oil circuit breaker have been discussed in a short detailed just to understand the basic concept about these circuit breakers. Oil circuit breakers pf test insulator electricity. Pdf types of circuit breaker and its application in. Plain break oil circuit breaker construction, working principle, application, pdf.
Electrical test equipment application solutions from megger. Proper lubrication will prevent most mechanical failures that lead to faults or arc flash. Oil circuit breakers breaker service substation spare. In bulk oil circuit breaker, oil performs mainly two functions. The arc is rapidly lengthened by means of the arc runners and arc chutes and the. The summarized important functions of circuit breakers are as follows. Salinas southern california edison bhavin desai electric power research institute jack harley firstpower group llc bob kinner firstpower group llc michael lebow coplanar consulting llc abstract.
Safe operation and maintenance of circuit breakers and switchgear. A low oil circuit breaker has the following disadvantages as compared to a bulk oil circuit breaker. It consists of current carrying contacts immersed in transformer oil and enclosed in a strong earthed metal tank. Bulk oil and minimum oil circuit breaker presented by saurabh dayal singh.
In oil circuit breaker fixed contact and moving contact are immerged inside the insulating oil whenever there is a separation of current carrying contacts in the oil, the arc in circuit breaker is initialized at the moment of separation of contacts, and due to this arc the oil. The circuit breaker can be operated manually or remotely from. Circuit breaker retrofit one very effective, proven option for the replacement of elderly oil filled switchgear is to replace the existing oil filled circuit breaker trucks with modern vacuum equivalent units. The are extinction process is carried out in the upper chamber. Firstly, it acts as an arc extinguishing medium and secondly, it insulates the live parts of the breaker from earth. Minimum oil circuit breakers mocbcontruction,working. Application, advantages and disadvantages of oil, minimum oil, air blast, sulfur hexafluoride, vacuum circuit breaker. When a fault occurs, the moving contacts are pulled down by the protective system and an arc is struck which vaporises the oil. The basic construction of bulk oil circuit breaker.
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