Fluke 1650B [26/62] Measuring loop line impedance

165XB

Users Manual

subtracts it from readings. The resistance value is saved even when power

is turned off so you don’t need to repeat the operation every time you use

the instrument.

4. Press and hold T until the reading settles. If the continuity beeper is

enabled, the tester beeps continuously for measured values less than 2 Ω

and there is no stable reading beep for measured values greater than 2 Ω.

If a circuit is live, the test is inhibited and the AC voltage appears in the

secondary (lower) display.

Measuring Loop/Line Impedance

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Figure 10. Loop/Line Impedance/Switch and Terminal Settings

Loop Impedance (Line to Protective Earth L-PE)

Loop impedance is source impedance measured between Line (L) and

Protective Earth (PE). You can also ascertain the Prospective Earth Fault

Current (PEFC) that is the current that could potentially flow if the phase

conductor is shorted to the protective earth conductor. The tester calculates the

PEFC by dividing the measured mains voltage by the loop impedance. The

loop impedance function applies a test current that flows to earth. If RCDs are

present in the circuit, they may trip. To avoid tripping, always use the Z

No Trip

function on the rotary switch. The no trip test applies a special test that

prevents RCDs in the system from tripping. If you are certain no RCDs are in

the circuit, you can use the Z

Hi Current function for a faster test.

Note

If the L and N terminals are reversed, the tester will auto-swap them

internally and continue testing. If the tester is configured for UK

operation, testing will halt. This condition is indicated by arrows above

or below the terminal indicator symbol (b).