User Manual

30 GMC-I Messtechnik GmbH
10.1 Earth Resistance, Mains Operation – 2-Pole Measurement with KS-PROFITEST INTRO or Country-Specific Measuring Adapter (Schuko)
Key
R
B
Operational earth
R
E
Earth resistance
R
i
Internal resistance
R
X
Earthing resistance through equipotential bonding sys-
tems
R
S
Probe resistance
PAS Equipotential bonding busbar
RE Overall earthing resistance (R
E1
//R
E2
//water pipe)
Earthing resistance can be estimated without a probe using the
“earth loop resistance measurement”.
The resistance value R
ELoop
obtained with this measuring
method also includes operational earth electrode resistance R
B
and resistance at phase conductor L. These values must be
deducted from the measured value in order to determine earthing
resistance.
If conductors of equal cross section are assumed (phase conduc-
tor L and neutral conductor N), phase conductor resistance is half
as great as supply impedance Z
L-N
(phase conductor + neutral
conductor).
Supply impedance can be measured as described in section 9
beginning on page 27. In accordance with DIN VDE 0100, the
operational earth electrode R
B
must lie within a range of “0 Ω to
2 Ω”.
1) Measurement: Z
LN
amounts to R
i
= 2 · R
L
2) Measurement: Z
L-PE
amounts to R
ELoop
3) Calculation: R
E1
amounts to Z
L-PE
– 1/2 · Z
L-N
; where R
B
= 0
The value for operational earth conductor resistance R
B
should be
ignored in the calculation of earthing resistance, because it is
generally unknown.
Calculated earthing resistance thus includes operational earth
conductor resistance as a safety factor.
If the parameter is selected, steps 1 through 3 are
executed automatically by the test instrument.
Select the Measuring Function
Set Parameters
❏ Measuring range: AUTO, 10 kΩ (4 mA), 1 kΩ (40 mA), 100 Ω
(0.4 A), 10 Ω (> 0.8 A). In systems with RCCBs, resistance or
test current must be selected such that it is less than tripping
current (½ I
∆N
).
❏ Connection type: 2-pole or Schuko (country-specific)
•
2-pole measurement via the KS-PROFITEST INTRO
(Z503L),
measuring range max. 10 kΩ
or
2-pole measurement via the PRO-Schuko
measuring adapter
(Z503K),
measuring range max. 10 kΩ
•
2-pole measurement via the PRO-Schuko
measuring adapter
(Z503K),
measuring range limited to 10 Ω,
as exact measurement is conducted
by means of a formula
❏ Touch voltage: UL < 25 V, < 50 V, < 65 V, < xx V
❏ Test current waveform: sinusoidal (full-wave), 15 mA sinusoidal
(full-wave), DC offset (DC-L or DC-H) and positive half-wave
DC-L: Minimal bias current allowing for faster measurement
DC-H: Higher bias current providing more reliability with regard
to non-tripping of the RCD
Ri
W
a
t
e
r
P
i
p
e
E
2
E
1
B
R
E
Limit Value:
R
E
> Limit Value
LIMIT