KYORITSU 4140 - Manual (Page 17)

̶ 15 ̶
-400msforfinalcircuitsnotexceeding32A(at230/400VAC)
-5sfordistributioncircuitsandcircuitsover32A(at230/400VAC)
The compliance with the above rules shall be verified by:
1)MeasurementofthefaultloopimpedanceZsbyLooptester.
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(PleaseseeRCDTESTsection).
ForinstanceinaTNsystemwithnominalmainsvoltageUo=230
V protected by General purpose gG fuses or MCBs (Miniature
CurrentBreakers)requiredbyIEC898/EN60898,theIaandmax
Zs values could be:
ProtectionbygGfuses
with Uo of 230V
ProtectionbyMCBswithUoof230V
(Disconnectiontime0.4and5s)
Rating
(A)
Disconnection
time 5s
Disconnection
time0.4s
Characteristic
B
Characteristic
C
Characteristic
D
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.
BelowisapracticalexampleofverificationoftheprotectionbyMCB
inaTNsystemaccordingtotheinternationalStandardIEC60364.