Earth leakage-earthing, Electrical Engineering

Earth Leakage : Earth leakage takes place when, through some fault in an appliance or its connections. Electric current escapes to earth i.e. the body of the appliance become 'live' and may give severe shocks. A minor earth fault is called as a earth leakage and under these conditions the appliance continues to work and gives mild shocks. However, if there is a major earth fault the loss of current to the earth causes the fuse to blow out if the body of appliance is earthed.

Increasingly, earth leakage circuit breakers (ELCBs), are being used to detect this loss of current as they can be sensitive to a loss of as little as 5 mA.

They can be bought to fit a 16 A socket or as individual components for each equipment or appliance. ELCBs can be too sensitive: for example, if neon indicator lamps are wired from live to earth, the tripping of EL,CB would take place very often. This kind of problem can be solved by rewiring the indicator lamps between live and neutral, though "nuisance tripping" can also be caused by slight moisture e.g. with refrigerators. A typical ELCB circuit is shown in Figure.

44_ELCB circuit diagram.png

Figure: ELCB circuit diagram.

Hazards in Laboratories In the event of a short circuit or leakage occurring, the circuit breaker will cut off the mains power supply and will continue to break the circuit until the fault is rectified.

It can be seen, then, that ELCBs are more sensitive than fuses and are more convenient to use. They are useful for protecting circuits supplying power tools, etc. where the risk of shock is high. However, ELCBs only protect the live conductor; for example, if the live conductor is short-circuited to earth.

ELCB would not prevent a fatal shock if both neutral and live conductors were touched by someone standing on an insulated surface. Now check your understanding of the principles of earthing electrical equipment by answering the following questions. You need only tick the answers you think are correct and compare them with ours.

Posted Date: 4/19/2013 5:36:49 AM | Location : United States

Related Discussions:- Earth leakage-earthing, Assignment Help, Ask Question on Earth leakage-earthing, Get Answer, Expert's Help, Earth leakage-earthing Discussions

Write discussion on Earth leakage-earthing
Your posts are moderated
Related Questions
Error-Rate Control, Output-Rate Control, and Integral-Error (Reset) Control Let us consider a typical second-order servomechanism(containing two energy-storing elements) whose

do you have a place where I can draw the equation out ?

Cite a specific example in which the engineer must provide maximum efficiency for a given cost

design using softwares (LEdit7, LTspice) the project has many aspects and I would like you to check them on the website with my personal password. in the project specifications (d

The coursework requires you to work in pairs to write a Java application that will take a numerical representation of a MIPS program and simulate its execution. MIPS is a Load-S

(a) Find v out in the circuit shown in Figure. (b) With V i = 2V, R 1 = R 2 = 2.5k, R 3 = 5k, and A = 100, find v out .

Q. Consider a 240-V supply feeding a resistive load of 10 kW through wires having a total resistance of R = 0.02 . For the same load, let a 120-V supply be used with a total wire

A relay is essentially an electromechanical switch that opens and closes electrical contacts. A simplified relay is represented in Figure. It is required to keep the fenomagnetic p

Define the Objectives of Load Flow Analysis The objectives of load flow analysis are: (i) To analyse an existing power system, future expansion or a new power system plan.