Fault loop impedance definition

Avoid those nasty electric shocks and injuries. The objective is to make sure that . The impedance of the earth fault current loop starting and ending at the point of earth fault. This impedance is denoted by the symbol (Zs).

Measuring earth- fault loop impedance and prospective short-circuit current.

Since the loop includes the resistance of phase and protective conductors within the installation, the highest values will occur at points furthest from .

Information about how the fault loop .

Unsuspected parallel grounds, in addition to increasing fault currents, can reduce voltage drop on the circuit and mask high impedance. Various methods, both specific and jury-rigge are used to determine voltage drop. But loop testers are the most accurate means of measuring impedance because they include actual . Current is driven through the loop impedance by the supply voltage. Check of phase sequence ( Regulation 612).

Functional testing (Regulation 613). It can be very inconvenient if an RCD is tripped by accident. For many installations the resistance of the earth electrode can be measured using an earth fault loop impedance.

An upstream protective device (ie:- RC MCB, MCBRC ELCB) needs to clear the original fault immediately, in order to protect the person who comes into indirect contact with the metal casing. Ground- fault loop impedance calculations in single-phase systems. To this purpose, the determination of the actual ground fault - loop impedance (which may, or may not, comprise the earth) is essential.

The over-riding requirement is that sufficient fault current must flow in the event of an earth fault to ensure that the protective device cuts off the supply before dangerous shock can occur. The fault loop impedance is higher, and unless the electrode impedance is very low indee a TT installation should always have an RCD (GFCI) as its first isolator. TT has always been preferable for . It is determined by the voltage and impedance of the supply system.

A programme of testing for earth fault loop impedance was undertaken as part of checks to ascertain why. Relating this to the disconnection time identified above, a maximum earth fault loop impedance of 1. The prospective short circuit current IPSC is defined as:. Z is equivalent to the loop resistance value R. MAXIMUM EARTH FAULT LOOP IMPEDANCE VALUES FOR.

OVERCURRENT PROTECTIVE DEVICES IN COMMON USE, FOR FAULT PROTECTION. For fault protection, the limiting values of earth fault loop impedances, Zs, are given in Tables 41. Copying of articles is not permitted except for.

RCD – is the reading shown on the . Your loop testing questions answered to assist you with getting the most out of your loop tester. Earthing thus involves using a.