Electrical

Melded Case Circuit Breaker (MCCB) : Molded case circuit breakers are tested and rated according to the UL489 Standard. Their current carrying parts, mechanisms and trip devices are completely contained within a molded case of insulating material. MCCBs are available in various frame sizes with various interrupting ratings for each frame size. Molded case circuit breakers are designed … Read more

Miniature circuit breaker (MCB) Actuator lever – used to manually trip and reset the circuit breaker. Also indicates the status of the circuit breaker (On or Off/tripped). Most breakers are designed so they can still trip even if the lever is held or locked in the “on” position. This is sometimes referred to as “free trip” … Read more

Air Break Circuit Breaker : Q. What are types of air circuit breakers? Draw neat sketch of one air circuit breakers and explain its working. Construction of Air Break Circuit Breaker : There are two sets of contacts. Main contacts and arcing contacts. Main contacts conduct the current in closed position of the breaker. They … Read more

Classification of Circuit Breakers : Circuit breakers can be classified by various methods however; the most general way of classification is on the basis of medium used for arc extinction. Various arc extinction medium used in circuit breakers is usually oil, air sulphur hexafluoride (SF6) or vacuum. According to above mediums, circuit breakers are classified … Read more

Methods of Arc Extinction : Q. State and explain the two different methods of arc extinction in a circuit breaker. Q. Explain the principle of arc extinction in C.B. Explain the arc phenomenon. Q. State the method of arc extinction. Q. what are the two different methods of arc extinction in circuit breakers? Explain each … Read more

Electrical Circuit Breaker Arc Formation Process : Q. What is arc formation process? Q. Define circuit breaker. Explain arcing phenomenon in circuit breaker. Arc Formation Definition : Refer Figure (a) circuit breakers contacts are in closed position. And entire cross section of conductor carries the current. Now when fault occurs on system a heavy current flows … Read more

Types of Construction of Isolators : Q. Describe the vertical break isolator in brief. Q. Explain with neat labeled constructional diagram : operation of vertical pantograph type Isolator Q. With the help of a neat diagram, explain the working of pantograph isolator in brief Vertical break type Horizontal break center rotating double break isolator Pantograph … Read more

Electrical Isolators : Q. What is the function of isolator in a power system? Q. State the sequence of operation of isolator, circuit breakor and earthing switches :        While closing the circuit        While opening the circuit Isolator (disconnecting switch) operates under no load condition. It does not have any … Read more

High Rupturing Capacity (H.R.C.) Fuses : Q. Explain the constructional detail of high rupturing capacity cartridge fuse with neat sketch. Q. Explain the constructional detail of H.R.C. fuse. Q. Explain with neat sketch the working of HRC fuse. Q. Explain the construction and working of HRC fuse with diagram. HRC fuse Construction & Working : Figure (A) … Read more