User Manual

36 GMC-I Messtechnik GmbH
10.6 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
2-pole adapter, clamp and probe are connected.
Set Parameters at Tester
❑ Measuring range (test current selection):
1 kΩ (40 mA), 100 Ω (0.4 A), 10 Ω (3.7 ... 7 A)
In the case of systems with RCCBs, the DC + functions
can be selected (only in the 10 Ω range and only with the
METRAFLEX P300).
❑ Connection type: 2-pole adapter + clamp
After parameter selection: automatic setting to 10 Ω measuring
range and 1 V/A or 1000 mV/A transformer ratio
❑ Contact voltage: UL < 25 V, < 50 V, < 65 V, see section 5.7 re-
garding freely selectable voltage.
❑ Test current waveshape:
Sinusoidal (full-wave), DC offset and positive half-wave
❑ 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
Selecting a 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 sensor
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.
P
R
O
F
I
T
E
S
T
W
a
t
e
r
P
i
p
e
SE
2
E
1
B
U
Probe
I
Clamp
--------------


R
E
Tester METRAFLEX P300 Clamp Tester
Transforma-
tion Ratio
Parameter
Switch Measuring
Range
Measuring
Range
1:1
1 V / A
3 A (1 V/A) 3 A
0.5 ... 100
mA
1:10
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