Manual

-400msforfinalcircuitsnotexceeding32A(at230/400VAC)

-5sfordistributioncircuitsandcircuitsover32A(at230/400VAC)

The compliance with the above rules shall be verified by:

1)MeasurementofthefaultloopimpedanceZsbyLooptester.

2) Verification of the characteristics and/or the effectiveness of the

associated protective device. This verification shall be made:

- for circuit-breakers and fuses, by visual inspection (i.e. short time

or instantaneous tripping setting for circuit-breakers, current rating

and type for fuses);

-for RCDs, by visual inspection and test using RCD testers

recommending that the disconnecting times mentioned above are

met(PleaseseeRCDTESTsection).

ForinstanceinaTNsystemwithnominalmainsvoltageUo=230

V protected by General purpose gG fuses or MCBs (Miniature

CurrentBreakers)requiredbyIEC898/EN60898,theIaandmax

Zs values could be:

ProtectionbygGfuses

with Uo of 230V

ProtectionbyMCBswithUoof230V

(Disconnectiontime0.4and5s)

Rating

(A)

Disconnection

time 5s

Disconnection

time0.4s

Characteristic

la(A) Zs(Ω) la(A) Zs(Ω) la(A) Zs(Ω) la(A) Zs(Ω) la(A) Zs(Ω)

6 17 13.5 38 8.52 30 7.67 60 3.83 120 1.92

10 31 7.42 45 5.11 50 4.6 100 2.3 200 1.15

16 55 4.18 85 2.7 80 2.87 160 1.44 320 0.72

20 79 2.91 130 1.77 100 2.3 200 1.15 400 0.57

25 100 2.3 160 1.44 125 1.84 250 0.92 500 0.46

32 125 1.84 221 1.04 160 1.44 320 0.72 640 0.36

40 170 1.35 -- -- 200 1.15 400 0.57 800 0.29

50 221 1.04 -- -- 250 0.92 500 0.46 1000 0.23

63 280 0.82 -- -- 315 0.73 630 0.36 1260 0.18

80 403 0.57 -- --

100 548 0.42 -- --

The most complete loop testers or Multifunction testers also

have the Prospective Fault current measurement. In this case,

Prospective Fault current measured with Instruments must be

higher than the tabulated Ia of the protective device concerned.

BelowisapracticalexampleofverificationoftheprotectionbyMCB

inaTNsystemaccordingtotheinternationalStandardIEC60364.