GMC-I Messtechnik GmbH
31
10.4
Selective Earth Resistance Measurement with Accessory Current Clamp Sensor
As an alternative to the classical measuring method, it is possible to perform measurements with a current clamp sensor.
Selective Earth Resistance Measurement (Mains Powered) – Connection Circuit Diagram
Key figure below
R
B
Operational earth
R
E
Earth resistance
R
L
Conductor resistance
R
X
Earth resistance via equipotential bonding systems
R
S
Probe resistance
PAS
Equipotential bonding strip
RE
Overall earth resistance (R
E1
// R
E2
// water pipe)
Measurement without clamp:
R
E
= R
E1
// R
E2
Measurement with clamp:
R
E
= R
E2
=
Select the Measuring Function
Connection
Connected components:
2-pole adapter, clamp sensor and probe
Set parameters at the test instrument
q
Connection type:
2-pole a clamp sensor
After parameter selection: automatic setting to 10
measuring range and transformer ratio of 100 mV/A
q
Transformer ratio of current clamp sensor:
see table below
q
Measuring range
(test current selection):
10 k
(4 mA), 1 k
(40 mA), 100
(0.4 A),
10
(> 0.65 A)
The DC +
function can be selected for systems with
RCCB.
q
Contact voltage:
UL < 25 V, < 50 V, < 65 V, freely selectable
voltage, see section 5.7
Setting Parameters at the Current Clamp Sensor
q
Measuring range of current clamp sensor:
see table below
Select the Measuring Range at the Current Clamp Sensor
Important Instructions Regarding the Use of the Current Clamp Sensor
•
Use
only the METRAFLEX P300 or Z312A current clamp
sensor for this measurement.
• Read and adhere strictly to the
operating instructions
for the
METRAFLEX P300 current clamp sensor, as well as the safety
precautions contained therein.
• Be sure to observe the
direction of current flow
(see arrow on the
current clamp sensor).
• The clamp must be
securely attached
for use. The sensor must
not be permitted to move during measurement.
• The current clamp sensor may only be used at an adequate
distance from
strong, extraneous fields
.
• Before use, always inspect the electronics housing, the
connector cable and the flexible current sensor for damage.
• In order to prevent electrical shock, keep the surface of the
METRAFLEX clean and free of contamination.
• Before use, make sure that the flexible current sensor, the
connector cable and the electronics housing are dry.
PRO
FITE
ST
wa
ter
pip
e
S
E
2
E
1
B
U
Sonde
I
Zange
-----------------
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
