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Electrical Installation Tester
Measurements
39
Loop Impedance in IT System Measurement
To measure the loop impedance at the mains socket, put the Tester in IT mode
(Power On option: + ). In the IT mode, the Tester accepts any voltage
between N and PE, but loop test with the High-current trip mode only. See
Figure 6.
R
LO
hwl055.eps
Figure 6. Loop Impedance Test in IT System
Line Impedance
Line impedance is source impedance measured between Line conductors or
Line and Neutral. This function allows these tests:
• Line to Neutral loop impedance.
• Line to Line impedance in 3-phase systems.
• L-PE loop measurement. This is a high-current, 2-wire loop measurement.
It cannot be used on circuits protected by RCDs because it will cause them
to trip.
• Prospective Short Circuit Current (PSC). PSC is the current that can
potentially flow if the phase conductor is shorted to the neutral conductor or
another phase conductor. The Tester calculates the PSC current as the
measured mains voltage divided by the line impedance.
To measure line impedance:
1. Turn the rotary dial to the
HI CURRENT position. See Table 15.
2. Connect the red lead to the L (red) and the blue lead to the N (blue)
terminals of the Tester.
3. Press to select L-N.
1.888.610.7664 sales@GlobalTestSupply.com
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