Manual

64 Gossen Metrawatt GmbH
15.6 Earthing Resistance Measurement, Mains Powered – Selective Earthing Resistance Measurement with Current Clamp Sensor
as Accessory
As an alternative to the conventional measuring method, measurement can also be performed with a current clamp sensor.
Key
R
B
Operational earth
R
E
Earthing resistance
R
L
Cable resistance
R
X
Earthing resistance through equipotential bonding
systems
R
S
Probe resistance
PAS Equipotential bonding busbar
RE Overall earthing resistance (R
E1
// R
E2
// water pipe)
Measurement without clamp: R
E
= R
E1
// R
E2
Measurement with clamp: R
E
= R
E2
=
Select Measuring Function
Select Operating Mode
Connection
To be connected: 2-pole adapter, clamp and probe
Set Parameters at Tester
❏ Measuring range (test current selection):
1 k (40 mA), 100  (0.4 A), 10  (3.7 … 7 A)
In the case of systems with RCCBs, the DC offset and positive
half-wave (DC + ) functions can be selected (only in the
10  range and only with the METRAFLEX P300).
❏ Connection: 2-pole adapter + clamp meter
After parameter selection: automatic setting to 10  measuring
range and 1 V/A or 1000 mV/A transformer ratio
❏ Touch voltage: UL < 25 V, < 50 V, < 65 V, for information regard-
ing freely selectable voltage see section 10.8
❏ Test current waveshape:
Sinusoidal (full-wave), DC offset and
positive half-wave (DC + )
❏ System type: TN/TT, IT
❏ Current clamp sensor transformation ratio: see table below
Set Parameters at Current Clamp Sensor
❏ Current clamp sensor measuring range: see table below
Select Measuring Range at the Current Clamp Sensor
Important Instructions for Use of the Current Clamp Sensor
• Use only the METRAFLEX P300 or the Z3512A current clamp
sensor for this measurement.
• Read and adhere to the operating instructions for
the METRAFLEX P300 current clamp sensor, as well as the
safety precautions included therein.
• Observe direction of current flow (see arrow on the current
clamp sensor).
• Use the clamp in the permanently connected state. The sen-
sor may not be moved during measurement.
• The current clamp sensor may only be used at an adequate
distance from powerful extraneous fields.
• Before use, always inspect the electronics housing, the con-
nector cable and the current sensor for damage.
• In order to prevent electric shock, keep the surface of the
METRAFLEX clean and free of contamination.
• Before use, make sure that the flexible current sensor, the con-
nector cable and the electronics housing are dry.
T
E
S
T
I
N
S
T
R
U
M
E
N
T
W
a
t
e
r
P
i
p
e
SE
2
E
1
B
U
Probe
I
Clamp
-----------------



R
E
Test Instrument METRAFLEX P300 Clamp Test Instrument
Parameters
Transformation Ratio
Switches Measuring
Range
Measuring Range
1:1
1 V / A
3 A (1 V/A) 3A 0.5 … 100 mA
01:10
100 mV / A
30 A (100 mV/A) 30 A 5 … 999 mA
1:100
10 mV / A
300 A (10 mV/A) 300 A 0.05 … 10 A