Sigma Institute of Engineering

Information Technology(1ST SEMESTER)

Prepared by; name en.number • Vikram rajpurohit 140500116033• Taxak mistery 140500116016• Pranay Patel 140500116026• Parth patel 140500116025• Paras patel 140500116024• Akshay rana 140500116034

INTRODUCTIONFrom 19th century use of electricity was started.Electricity is usefull in domestic & industrial

purpose.Proper precautions should be taken for the

safety and protection of electricity otherwise it may even lead to death.

Elements of electrical

engineering Circuit protection devices

• Fuses • MCB• ELCB• RELAY

FuseS Fuse Is simplest device,which

brakes the circuit under abnormal condition

It is used for overload/short circuit protection in medium voltage (up to 33kV) and low voltage (up to 400V) installations.

CONSTRUCTION OF FUSE

• The main components of a standard fuse unit consist of the

following items:I. Metal fuse elementII. Set of contactsIII.Support bodyIV. Connection

Fuses Glass Cartridge

Mini fuse

Auto fuse

Maxi fuse

ADVANTAGES OF FUSESSpeed of operation is very highMaintenance cost is practically zeroThey are capable of clearing high as well

as low faults currentthey provide reliable operation

DISADVANTAGESHead produced by the arc may affect the associated switches

They have to be replaced after each operation

MCBMiniature circuit breaker and moulded

case circuit have a feature of a good h.r.c. fuse and a good switch.

These can be used for switching purpose under normal operating condition and circuit breaker under overloading.

MCBAll other metal parts are made up of

nonferrous ,non-rusting type materials.These are used in low voltage domestic,

commercials and industrial application.

DIMENSION OF MCB

symmetricalrail external

partdepth

width

Earth leakage circuit breaker (elcb)the metal housing of the induction of the

induction motor is always connected to earth. if the user standing on earth touches the “live”

point, the protection against such current is essential

and it is provide by device called (elcb) operation under the fault condition

Earth leakage circuit breaker (elcb)when the fault occurs , the leakage current

start flowing through conductor as Explained earlier.So there will be non zero flux set up in current transformer core.

specificationminiature circuit breaker are available

following…Current ratting : 5,10,15,20,30,40 ampVoltage rating :a.c. voltage rating –

240v/415 d.c. voltage ratting –

50v/110Rupturing capacity : 3ka at 50v

RelaysRelays use an electromagnet to operate a

switching mechanism mechanically , but other operating principles are also used.

Relays are used where it is necessary to control a circuit by low power signal or where several circuits must be controlled by 1 signal.

RelaysA type of relay that can handle the high power

required to directly control an electric motor or other loads is called a contactor.

Solid state relays control power circuits with no moving parts instead using a semiconductor device to perform switching .

CONCLUSIONI have collected some information from my study material and some from internet.I have studied about all aspect of “FUSES, MCB, ELCB And RELAY”And prepared this document as per my best knowledge.

GUIDED BY; Prof. Mustakim Haveliwala