Instructions

42 GMC-I Messtechnik GmbH
10.10 Earthing Resistance Measurement, Battery Powered – Ground Loop Measurement
(with current clamp sensor and transformer, plus PRO-RE/2 measuring adapter as accessory) (only MPRO & MXTRA)
2-Clamp Measuring Method
In the case of earthing sys-
tems which consist of sev-
eral earth electrodes (R1 ...
Rx) which are connected to
each other, earthing resis-
tance of a single electrode
(Rx) can be ascertained with
the help of 2 current clamps
without disconnecting Rx or
using spikes.
This measuring method is
especially well suited for
buildings or systems for
which probes and auxiliary
earth electrodes cannot be used, or where it’s impermissible to
disconnect earth electrodes.
Furthermore, this “spike-free” measurement is performed as one
of three measurements for lightning protection systems, in order
to determine whether or not current can be dissipated.
Figure at right:
PRO-RE/2 measuring adapter as
accessory for connecting the E-
Clip 2 generator current clamp
Connection
➭ No probes or auxiliary earth electrodes are required.
➭ The earth electrode is not disconnected.
➭ Attach the PRO-RE/2 adapter (Z502T) to the test plug.
➭ Connect the E-Clip 2 generator clamp (current clamp transformer)
via the 4 mm safety plugs at the PRO-RE/2 adapter.
➭ Connect the Z3512A current clamp sensor to jacks 15 and 16 at
the test instrument.
➭ Attach the 2 clamps to an earth electrode (earth spike) at dif-
ferent heights with a clearance of at least 30 cm.
Select Measuring Function
Select Operating Mode
The selected operating mode is displayed inversely:
white battery icon against black background.
Set Parameters at Tester
❑ Measuring range: in this case always AUTO
Note
After selecting to 2-clamp measurement, switching to the
AUTO range takes place automatically. It is then no longer
possible to change the range!
❑ Connection type: 2-clamp
❑ Current clamp sensor transformer ratio:
1:1 (1 V/A), 1:10 (100 mV/A), 1:100 (10 mV/A)
❑ Distance d (for measuring
ρ
E
): irrelevant in this case
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 Z3512A current clamp sensor for this measure-
ment.
•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.
• Make sure that the connector cables from the two clamps are
laid separate from each other to the greatest possible extent.
Start Measurement
PROFITEST MPRO, PROFITEST MXTRA
Tester Z3512A Clamp
Transforma-
tion Ratio
Parameter
Switch Measuring
Range
1:1
1 V / A
1 A / x 1 1 A
1:10
100 mV / A
10 A / x 10 10 A
1:100
10 mV / A
100 A / x 100 100 A
R
E