Each Fluke product is warranted to be free from defects in material and workmanship under normal use and
service. The warranty period is two years and begins on the date of shipment. Parts, product repairs, and
services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of
a Fluke authorized reseller, and does not apply to fuses, disposable batteries, or to any product which, in
Fluke's opinion, has been misused, altered, neglected, contaminated, or damaged by accident or abnormal
conditions of operation or handling. Fluke warrants that software will operate substantially in accordance
with its functional specifications for 90 days and that it has been properly recorded on non-defective media.
Fluke does not warrant that software will be error free or operate without interruption.
Fluke authorized resellers shall extend this warranty on new and unused products to end-user customers
only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is
available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the
applicable international price. Fluke reserves the right to invoice Buyer for importation costs of
repair/replacement parts when product purchased in one country is submitted for repair in another country.
Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair,
or replacement of a defective product which is returned to a Fluke authorized service center within the
warranty period.
To obtain warranty service, contact your nearest Fluke authorized service center to obtain return
authorization information, then send the product to that service center, with a description of the difficulty,
postage and insurance prepaid (FOB Destination). Fluke assumes no risk for damage in transit. Following
warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke
determines that failure was caused by neglect, misuse, contamination, alteration, accident, or abnormal
condition of operation or handling, including overvoltage failures caused by use outside the product’s
specified rating, or normal wear and tear of mechanical components, Fluke will provide an estimate of repair
costs and obtain authorization before commencing the work. Following repair, the product will be returned to
the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges
(FOB Shipping Point).
THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. FLUKE SHALL NOT BE LIABLE
FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES,
INCLUDING LOSS OF DATA, ARISING FROM ANY CAUSE OR THEORY.
Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or
limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not
apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court or other
decision-maker of competent jurisdiction, such holding will not affect the validity or enforceability of any other
provision.
The 1625-2 Earth Ground Tester (Tester or Product) is a compact, field-rugged
instrument that performs all four types of earth ground measurement. Specifically, the
Tester is able to measure earth ground loop resistances using only clamps – called
Stakeless testing. This method doesn’t require the use of earth ground stakes or the
disconnection of ground rods.
The Tester features:
• One-button measurement concept
• 3-pole and 4-pole earth ground measurement
• 4-pole soil resistivity testing
• Selective testing, no disconnection of ground conductor (1 clamp)
•Automatic Frequency Control (AFC) – identifies existing interference and chooses a
measurement frequency (94, 105, 111, 128 Hz) to minimize its effect, providing a
more accurate earth ground value.
•R* measurement – calculates earth ground impedance at 55 Hz to more accurately
reflect the earth ground resistance that a fault-to-earth ground would see.
•Adjustable limits – for quick test result verification.
At locations involving the generation, distribution and consumption of electrical energy,
certain safety measures must be met in order to protect human life. In many cases, these
safety measures are national and international regulations which must be checked
regularly. Grounding, the connection of exposed conductive parts to the earth in case of a
fault, represents the most fundamental safety measure. There are requirements for
grounding of transformers, high and medium voltage power pylons, railway tracks, tanks,
vats, foundations and lightning protection systems.
The effectiveness of grounding systems should be checked using a earth/ground tester
such as the 1625-2 which checks the effectiveness of connections to the ground. The
1625-2 provides the perfect solution by combining the latest technology into a compact,
field-rugged instrument. In addition to performing standard 3-pole and 4-pole ground
resistance measurements, an innovative process accurately measures individual earth
electrode resistances in single and meshed earthed systems without disconnecting any
parallel electrodes. One specific application of this capability is quick and accurate
measurement of power pylon grounds. The 1625-2 has automatic frequency control
(AFC) to minimize interference. Before measuring, the instrument identifies existing
interference and selects a measurement frequency to minimize its effect.
Notes
•The terms earth and earthing also refer to ground and grounding and
interchan
geably throughout this m
anual.
is used
•For sta
Clam
clamp set.)
•Selective m
keless earth resistance measurements, the Selectiv
p Set (EI-1623) must be purchased. (The1625-2 Kit include
e/Stakeless
s this
easurements are described in the main section of this m
A Warning identifies hazardous conditions and procedures that are dangerous to the
user. A Caution identifies conditions and procedures that can cause damage to the
Product or the equipment under test.
Warning
To prevent possible electrical shock, fire, or personal injury:
• Read all safety information before you use the Product.
• Use the Product only as specified, or the protection supplied by
the Product can be compromised.
• Do not use the Product if it operates incorrectly.
• Do not use the Product if it is damaged.
• Do not use test leads if they are damaged. Examine the test leads
for damaged insulation, exposed metal, or if the wear indicator
shows. Check test lead continuity.
•Do not use the Product around explosive gas, vapor, or in damp
or wet environments.
•Do not apply more than the rated voltage, between the terminals
or between each terminal and earth ground.
•Use only current probes, test leads, and adapters supplied with
the Product.
•Do not use a current measurement as an indication that a circuit
is safe to touch. A voltage measurement is necessary to know if a
circuit is hazardous.
•The battery door must be closed and locked before you operate
the Product.
•Replace the batteries when the low battery indicator shows to
prevent incorrect measurements.
• Do not connect directly to mains.
• Do not touch voltages >30 V ac rms, 42 V ac peak, or 60 V dc.
Table 1 is a list of symbols used on the Tester and in this manual.
Table 1. Symbols
Symbol Description
Risk of Danger. Important information. See Manual.
Conforms to relevant Australian EMC requirements.
Storage
If the Tester is stored for an extended period of time or is not in use for a long time, you
should remove the batteries.
Hazardous voltage. Risk of electrical shock.
Battery Indicator
Conforms to European Union directives.
Conforms to relevant South Korean EMC Standards.
This product complies with the WEEE Directive (2002/96/EC) marking
requirements. The affixed label indicates that you must not discard this
electrical/electronic product in domestic household waste. Product Category:
With reference to the equipment types in the WEEE Directive Annex I, this
product is classed as category 9 "Monitoring and Control Instrumentation”
product. Do not dispose of this product as unsorted municipal waste. Go to
Fluke’s website for recycling information.
An external current transformer is available as an option, see Figure 1. The
transformer has a transformation ratio between 80 and 1200:1 for the measurement of a
single branch in mesh-operated earthing systems. This enables the user to measure on
high voltage pylons without separating the overhead earth wires or earth strips at the
bottom of the pylons. It is also used to measure lightning protection systems without
separating the individual lightning protection wires.
1
3
NORMA
1000
500
A 6805 06211
200
!
2
Figure 1. External Current Transformer EI-162BN
Transformer half (2)
Transformer end faces have bolts that pivot to aid in separating the Transformer
halves. One Transformer end face has a slotted bolt hole that allows the bolt to
pivot out of the end face.
Transformation ratio connections: ⊥, 200, 500, and 1000
Fastener (2)
The 1625-2 Earth/Ground Tester (Tester) is an earth resistance meter with fully
automated measuring frequency selection process. The Tester includes automatic testing
of probe and auxiliary earth electrode resistances and possible interference voltages in
accordance with DIN IEC61557-5/EN61557-5:
• Measurement of interference voltage (U
• Measurement of interference frequency (F
• Measurement of probe resistance (R
• Measurement of auxiliary earth electrode resistance (R
• Measurement of earthing resistance 3-pole, 4-pole, (R
external clip-on current transformer for selective measurement of single earthing
branches in mesh operated earthing systems
• Resistance measurement 2-pole with ac voltage (R~)
• Resistance measurement with dc voltage 2-pole, 4-pole, (R)
With its various possibilities of measurement and the fully automated measuring
sequence control (incl. automatic frequency control AFC), this instrument offers the latest
measuring technology in the field of earthing resistance measurements. By means of the
selectable limit input with visual and acoustical confirmation/error message and with the
code programmable and customer defined special functions, such as measuring voltage
20 V (for agricultural systems), earthing impedance R* (measuring frequency 55 Hz)
switched on or off, these instruments are individually programmable for use as a simple
meter as well as a high end fully automated measuring device.
)
ST
)
ST
)
S
)
H
) with or without using the
E
The Tester includes automatic testing of probe, auxiliary earth electrode resistances, and
possible interference voltages.
See Table 3 for a list of features and functions.
Warning
• No voltage permissible to sockets .
• Do not open or close the instrument with force.
• Disconnect all leads before opening the instrument.
Hardware malfunction
(for example, current
overload).
EE PROM memory
access malfunction.
Internal computation
malfunction.
Thermal overload. Cool thoroughly.
Switch ON/OFF if still
faulty.
The symbol may
appear when using the
stakeless
measurement on low
resistance circuits.
Contact service.
flashes on display
Setup
Batteries
Rechargeable batteries may be used but must be charged outside of the
instrument. The number of measurements available with these cells will
typically be different to those available using alkaline cells.
This Tester is equipped with six 1.5 V batteries IEC LR6 type AA. Replace or recharge
the batteries if the battery indicator shows 1 or 0 bars.
To insert the batteries:
1. Switch off instrument, see Figure 2.
2. Disconnect all test leads.
3. Open battery compartment.
4. Insert batteries. Always replace the complete set of batteries.
The functions are selected with the central rotary switch. Four push buttons start
measurements, read out supplementary measurement values, and select special
functions. See Table 6 for more information.
Measurement values are shown on a liquid crystal display with units. Additional special
characters indicate measurement mode, operating condition and error messages.
The Tester includes these measurement functions:
• Interference Voltage (UST)
• Interference Frequency (F
• Earthing Resistance (R
• Selective Measurement of
Earthing (R
• Resistance (R~)
• Low Resistance (R)
• Checking for Correct
Measurement Connection
• Beeper
• Battery Level Indicator
)
E
)
E
Fullwave rectification for dc and ac. If limit values are
exceeded no measurement will be started.
)
ST
For interference voltage >1 V its frequency is derived
from the period time.
The earthing resistance is determined by a 3-pole or
4-pole current and voltage measurement. The
measuring voltage is a square pulse ac voltage with 48 /
20 V and a frequency of 94, 105, 111 or 128 Hz. The
frequency can be selected manually or automatically
(AFC). 55 Hz in function R*.
Measurement of a single earth electrode in a mesh
operated (parallel) earthing system. The current flowing
through the single earth electrode is measured with an
external current transformer.
The resistance is determined by a 2-pole current and
voltage measurement. The measuring voltage is a
square pulse ac voltage with 20 V and a frequency of
94, 105, 111 or 128 Hz. The frequency can be selected
manually or automatically (AFC).
The resistance is determined by dc current and voltage
measurement. 2-pole as well as 4-pole measurement is
possible. The short circuit current is > 200 mA. The
resistance of both current directions is measured and
stored.
The Tester checks if the measuring lead is properly
connected according to the selected function via
isolated, two piece contacts, inside of each 4 mm
(banana) input socket, in combination with detection
circuitry. A wrong or missing connection is indicated by
an optical and acoustical signal.
The built-in beeper has two functions:
• Send message if set limit values are exceeded.
• Indicates dangerous condition or faulty operation.
A 4-segment battery level indicator shows the battery
status.
To prevent possible electrical shock, fire, or personal injury, use the
instrument on voltage free systems only.
1. Set measuring function with the central rotary switch.
2. Connect the measurement leads to the instrument.
3. Start measurement with "START TEST" button.
4. Read out measured value.
Advanced Operation
Power On Functions
At power on of the instrument with the central rotary switch, it is possible to access
certain operating conditions by pressing specific button combinations:
a) Standard mode
If the device is put into operation without further button control, it switches into a battery
saving condition (Stand by-display "---") approximately 50 seconds after the termination
of a measurement, or after a button push or turn of the rotary switch. Pressing the
"DISPLAY MENU" reactivates the instrument; the "old" measured values can be read out
again. After 50 min. of stand by the Display is turned off completely. Instrument is
reactivated with ON / OFF on the rotary switch
b) Stand by disable
A simultaneous push of buttons "DISPLAY MENU" and "CHANGE ITEM" at power on
prevents the instrument from being switched off automatically (Stand by). The battery
saving mode is reactivated with ON / OFF on the central rotary switch.
By keeping the "DISPLAY MENU" button pressed during power on, the display test can
be prolonged for any length of time. Return to the standard operation mode by pressing
any button or turning of the central rotary switch.
d) Number of software version
By keeping the "SELECT" button pressed during the power on sequence, the software
version is indicated on the display. By pressing the "DISPLAY MENU" button a switch
over to the last calibration date is possible. This display sequence is terminated by
turning the central rotary switch or pressing the "START TEST" button.
Display format: SOFTWARE-version: X. X X
The measuring functions have two initial operational modes: the Control loop and the
Measuring loop.
Control Loop
After turning the function rotary switch, the voltage display mode is reached. Pushing
"DISPLAY MENU" now calls up the control loop. According to the selected measuring
function, different setting values can be displayed and changed in the control loop. The
"DISPLAY MENU" button switches between the different set values inside a continuous
loop. The "SELECT" button selects the setting to be changed. Pushing the "CHANGE
ITEM" button the instrument either switches between certain set values or increases the
decimal point selected with "SELECT" by 1.
After parameter setting has been finished the next display can be called with "DISPLAY
MENU" or the measurement can be started with "START TEST".
This loop is entered by pressing the "START TEST" button. After releasing "START
TEST" the last measured value stays on the display. By repeated pressing of the
"DISPLAY MENU" button all supplementary values can be called. If a measured value
exceeds or falls below the pre-set limit, the limit can be displayed as well (with "DISPLAY
MENU"). In that case the measured value is diplayed with a flashing "LIMIT" whereas the
limit value is displayed with a steady "LIMIT"-symbol.
Inside the measuring loop parameters cannot be changed.
Further possibilities of button operation:
Warning sound () cancel with "DISPLAY MENU" (with display switchover) or with
"CHANGE ITEM" or "SELECT" button (without display switchover).
The instrument implements an automatic check, corresponding to the measurement
selected, to see if the correct input sockets are used.
The display symbols and
Figure 4.
From the way the symbols are displayed, the validity of the connected wiring can be
concluded by the following features:
• socket incorrectly wired (or, by mistake, not wired): corresponding symbol flashes.
• socket correctly wired: corresponding symbol is steady active
• socket with no connection: corresponding symbol is blank
are assigned to a specific socket as shown in
Interference - Voltages and Frequencies Measurement
This measuring function detects possible interference voltages and their frequencies.
This function is automatically active in every switch position before an earthing or
resistance measurement. If the pre-set limit values are exceeded, the interference
voltage is indicated as too high and a measurement automatically prevented. The
frequency of an interference voltage is only measurable if the level of this interference
voltage is higher than 1 V.
Bring central rotary switch in desired position, read out measured value of interference
voltage, measured value of interference frequency is displayed with "DISPLAY".
This instrument is equipped with a 3-pole as well as a 4-pole resistance measurement
that renders measurements of resistances of earthing systems possible, as well as
measurements of the soil resistivity of geological strata. A specific description of the
different applications is given further on in this manual. As a special function, the
instrument offers measurements with an external current transformer, with which a
measurement of single resistance branches in interlinked networks (lightning protection
and high voltage pylons with cabling) can be performed without separating parts of the
system. See Figure 3.
To ensure most feasible interference suppression during measurements, the instrume n t
is equipped with four measuring frequencies (94 Hz, 105 Hz, 111 Hz, 128 Hz), with
automatic switch over if necessary (AFC - Automatic Frequency Control). The
corresponding measuring frequency used for a specific measurement can be called and
displayed with DISPLAY MENU after the measurement. Additionally, one of the four
measuring frequencies can be selected and permanently set in special cases. In that
case, in order to stabilize the display, an average measurement can be carried out for up
to 1 minute by keeping the START TEST button pressed.
To determine the earthing impedance (R*) a measurement with a frequency close to the
mains frequency (55 Hz) is carried out. At the activation of R* through user's code, this
measuring frequency is activated automatically.
To keep the instrument as simple as possible at the time of delivery, all special functions,
such as LIMIT input, BEEPER programming, and measurement of earthing impedance
(R*) are not activated at delivery. They can be activated with personalized user's code
(see How to Change All Data Settings with Personalized CODE).
G
I
E
E
R
E
U
E
Umeas.
I
S
S
R
S
H
H
R
H
edw011.eps
Figure 3. Method for Earthing Resistances Measurement
This measuring function measures earthing and earth dissipation resistances of single
earth electrodes, foundation earth electrodes and other earthing systems by using two
earth spikes. See Figure 4.
4 Pole
Auxiliary
earth
Earth
electrode
>20 m>20 m
Probe
Figure 4. 3-Pole/4-Pole Measurement of Earthing Resistance - Process
electrode
edw012.eps
1. Turn central rotary switch to position "R
3pole" or "RE 4pole"
E
The instrument is to be wired according to picture and notices given on the display.
A flashing of the sockets symbols or , points to an incorrect or
incomplete connection of the measuring lead.
2. Press "START TEST" button.
Now a fully automated test sequence of all relevant parameters like auxiliary earth
electrode and probe and earth electrode resistance is implemented and finished with
the display of the result R
Before setting the earth spikes for probe and auxiliary earth electrode make sure that the
probe is set outside the potential gradient area of earth electrode and auxiliary earth
electrode. Such a condition is normally reached by allowing a distance of >20 m between
the earth electrode and the earth spikes as well as of the earth spikes to each other.
An accuracy test of the results is made with another measurement following repositioning
of the auxiliary earth electrode or probe. If the value stays the same, the distance is
sufficient. If the measured value changes, probe or auxiliary earth electrode must be
repositioned until the measured value R
stays constant.
E
Spike wires should not run too close to each other.
3-pole measurement with longer earth electrode connecting leads
Use one of the accessory cable drums as earth electrode connecting lead. Spool off
cable completely and compensate line resistance as described in Compensation of Earth Electrode Connecting Lead.
Time average measurement:
If there is a warning, MEASURED VALUE UNSTABLE, (see Table 5) after a test
sequence, most likely it is caused by strong interference signals, such as unsteady noise
voltage. Nevertheless, to get reliable values, the instrument offers the possibility of
averaging over a longer period.
1. Select a fixed frequency (see Control Loop).
2. Keep the "START TEST" button pressed until the warning "measured value unstable"
disappears. Maximum averaging time is approximately 1 minute.
Measurement of Single Earth Electrode Resistances in Mesh Operated Earthing
Systems Using Selective Clamp Method
This measuring method has been created to measure single earth electrodes in
permanently wired or mesh-operated systems (for example, a lightning protection system
with several electrodes or high voltage pylons with earth cabling). By measuring the
actual current flow through the earth electrode, this special measuring method provides
the unique possibility to measure selectively only this particular resistance by means of a
clip-on transformer (accessory). See Figure 5. Other parallel resistances applied are not
taken into account and do not distort the measuring result.
A disconnection of the earth electrode before the measurement is therefore no longer
necessary.
I
I
3
R
E
R
R
E
1
E
2
3
R
E
G
I
Z
tr
A
U
meas.
=
3
I
3
=
U
V
R
meas.
.
tr
U
meas.
Aux. Earth
R
Electrode
H
edw014.eps
Probe
S
I
Z
Figure 5. Measurement of Single Earth Electrode Resistances in Mesh Operated Earthing
Systems
Errors of the current transformer can be corrected as described in Clip-On Transformer
Errors Correction.
3-Pole/4-Pole Measurement of Single Earth Electrode Resistances
Turn central rotary switch to position " RE 3pole" or " RE 4pole". The instrument is
to be wired according to Figure 6 and messages on the display.
12
4 Probe
E/C1
Earth
electrode
34
START
Figure 6. 3-Pole/4-Pole Measurement of Single Earth Electrode Resistances
A flashing of the sockets symbols or , points to an incorrect or incomplete
connection of the measuring lead.
Fix clip-on transformer around the earth electrode to be measured.
Make sure that the clip-on transformation ratio set on the instrument corresponds to the
clip-on transformer used. Change settings if necessary (see How to Change All Data Settings with Personalized Code).
S/P2
H/C2
>20 m>20 m
edw015.eps
Note
The ratio that is preset from factory is correct for the EI162X sensing clamp.
Now a fully automated test sequence of all relevant parameters like auxiliary earth
electrode and probe and earth electrode resistance is implemented and finished with the
display of the result R
.
E
1. Read out measured value R
2. Call R
and RH with "DISPLAY MENU".
S
.
E
Remarks for the Setting of Earth Spikes
Before setting the earth spikes for probe and auxiliary earth electrode make sure that the
probe is set outside the potential gradient of earth electrode and auxiliary earth electrode.
Such a condition is normally reached by allowing a distance of >20 m between the earth
electrode and the earth spikes as well as to the earth spikes to each other. An accuracy
test of the results is made by another measurement following repositioning of the
auxiliary earth electrode or probe. If the value stays the same, the distance is sufficient. If
the measured value changes, probe or auxiliary earth electrode must be repositioned
until the measured value RE stays constant.
Spikes wires should not run too close.
3-pole Measurement with Longer Earth Electrode Connecting Leads
1. Use one of the accessory cable drums as earth electrode connecting lead.
2. Spool off cable completely and compensate line resistance as described in
“Compensation of Earth Electrode Connecting Lead”.
Time Average Measurement
If there is a warning "MEASURED VALUE UNSTABLE" (see Table 5) after a test
sequence, most likely it is caused by strong interference signals (for example, unsteady
noise voltage). To get reliable values, the instrument offers the possibility of averaging
over a longer period.
1. Select a fixed frequency (see Control Loop).
2. Keep the "START TEST" button pressed until the warning "MEASURED VALUE
UNSTABLE" disappears. Maximum averaging time is approximately 1 minute.
Measuring the Earthing Resistance without Disengaging the Overhead Earth Wire Using the
Selective Clamp Method
The measurement of the earth resistance of a single high voltage pylon usually requires
the overhead earth wire to be disengaged (lifted off) or the separation of the earthing
system from the pylon construction. Otherwise, false reading of the resistance of the
pylon earth electrode are liable to occur because of the parallel circuit of the other pylons
connected to each other by an overhead earth wire.
The new measuring method employed in this instrument - with its external current
transformer to measure the true current flowing through the earth electrode - allows
measurements of earth electrode resistances without disconnection of the earthing
system or disengaging the overhead earth wire. See Figure 7.
12
4 Probe
>20 m>20 m
34
START
Figure 7. Earthing Resistance without Disengaging the Overhead Earth Wire
As all four pylon stubs are connected to the foundation earth of the pylon, the measuring
current I
is divided into five components according to the present resistances
meas
involved.
One part flows via pylon construction to the overhead earth wire and further to the
parallel circuited pylon earthing resistances.
The other four current components (I
The addition of all currents result in a current I
... I4) flow via each individual pylon foot.
1
going through the earthing resistance, for
E
example, the resistance of the "composite" earth electrode to the soil.
If the current transformer is fixed to each pylon stub, one after the other, four resistances
have to be measured which show a behavior inversely proportional to the corresponding
current components I
... I4. The feeding point of the measuring current is to be left
1
unchanged to avoid a change in the current distribution.
Accordingly, these equivalent resistances are displayed as:
U
meas
=
R
Ei
Therefore the earthing resistance R
li
of the pylon is determined as a parallel circuit of the
E
individual equivalent resistances:
R
=
E
1
+++
1. Turn central rotary switch to position “R
1111
RRRR
4321
EEEE
3pole" or RE 4pole". The instrument
E
is wired according Figure 7 and messages on the display.
A flashing of the sockets symbols or , points to an incorrect or
incomplete connection of the measuring lead.
2. Apply current transformer to the pylon stub. Make sure that the transformation ratio
set on the instrument corresponds to the current transformer used. Change settings if
necessary (see “Changing of All Data Settings with Personalized CODE”).
3. Press “START TEST” button.
Now a fully automated test sequence of all relevant parameters like auxiliary earth
electrode, probe and earth electrode resistances, is implemented and finishes with
the display of the result R
Before setting the earth spikes for probe and auxiliary earth electrodes make sure that
the probe is set outside the potential gradient of earth electrode and auxiliary earth
electrode. Such a condition is normally reached by allowing a distance of >20 m between
the earth electrode and the earth spikes as well as to the earth spikes to each other. An
accuracy test of the results is made with another measurement after repositioning of
auxiliary earth electrode or probe. If the result is the same, the distance is sufficient. If the
measured value changes, probe or auxiliary earth electrode must be repositioned until
the measured value R
remains constant. Spike wires should not run too close.
E
1. Apply current transformer to next pylon stub.
2. Repeat measuring sequence.
Current feeding point of measuring current (alligator clip) and the polarity of the split
core current transformer has to be left unchanged.
After values of R
for each pylon foot are determined, the actual earth resistance RE
Ei
is calculated:
R
=
E
1
+++
1111
RRRR
4321
EEEE
Note
If the displayed R
value is negative despite correct orientation of the
E
current transformer, a part of the measuring current is flowing upwards into
the tower body. The earthing resistance, thus coming into effect, correctly
calculates if the individual equivalent resistances (under observation of their
polarity) are inserted into the equation above.
Time average measurement:
If there is a warning "MEASURED VALUE UNSTABLE" (see Table 5) after a test
sequence, most likely it is caused by strong interference signals such as unsteady noise
voltage.
For reliable values, the instrument offers averaging over a longer period:
1. Select a fixed frequency (see Control Loop).
2. Keep the "START TEST" button pressed until the warning "MEASURED VALUE
UNSTABLE" disappears. Maximum averaging time is approximately 1 minute.
For the calculation of short circuit currents in power supply plants, the complex earthing
impedance is important. Direct measurement is possible under the following conditions:
Phase angle at 50 Hz: 30 °... 60 ° inductive
Auxiliary earth electrode (ohmic): >100 • Z
Measuring process:
The measurement of the earthing impedance (R*) is only possible if it is activated by
putting in a personalized user's code (see "Change of Setup Data with Personalized
Code"). If this measuring function is activated, in every measurement of the four R
positions, the earthing impedance R* is displayed before all other measured values.
Clip-On Transformer Errors Correction
If the measurement of an earthing resistance by means of a clip-on transformer results in
a significantly different value as if measured without the clip-on, the deviation may be due
to the tolerances of the clip-on current transformer. This error can be corrected by fine
tuning the clip-on transformation ratio (basic settings 1000:1). This correction applies to
the transformer current range it was performed with. For other ranges a different
correction may be necessary.
1. Connect a low Ohm resistor (approximately 1 Ohm - in the range you want to correct)
as shown in Figure 8.
If the line resistance to the earth electrode cannot be ignored, a compensation of the
connecting lead resistance to the earth electrode is possible.
Measuring process:
Auxiliary
Earth
electrode
earth
electrode
Figure 10. Compensation of Earth Electrode Connecting Lead
edw019.eps
To do a compensation:
1. Turn central rotary switch to position "R
3pole".
E
2. Wire instrument as shown in Figure 10.
3. Call display R
with "DISPLAY MENU" button.
K
4. Implement compensation with "START TEST" button.
The compensation resistance is displayed only for as long as the "START TEST" button
is kept pressed. After releasing the "START TEST" button the measured value is stored
and the measuring instrument returns to the standard settings at the beginning of the
measurement so that a succeeding measurement of the earthing resistance can be
implemented by pressing "START TEST" again. Thereafter, R
is subtracted from the
K
actual measured value.
If the compensation value has to be reset to the basic setting (0.000 Ω), the
compensation sequence has to be implemented with an open (disconnected) measuring
lead or turn the switch to the next position and back.
The soil resistivity is the geological and physical quantity for calculation and design of
earthing systems. The measuring procedure shown in Figure 11 uses the method
developed by Wenner (F. Wenner, A method of measuring earth resistivity; Bull. National
Bureau of Standards, Bulletin 12 (4), Paper 258, S 478-496; 1915/16).
12
aaa
34
START
Figure 11. Measurement of Soil Resistivity
1. Four earth spikes of the same length are positioned into the soil in an even line and
with the same distance "a" to each other. The earth spikes should not be deeper than
a maximum of 1/3 of "a".
2. Turn central rotary switch to position "R
The instrument is to be wired according to picture and notices given on the display.
A flashing of the sockets symbols or , points to an incorrect or
incomplete connection of the measuring lead.
, the soil resistivity calculates according to the
E
equation:
=
ρ
...... mean value of soil resistivity (Ωm)
E
R
...... measured resistance (Ω)
E
Ra..2
EE
a ...... probe distance (m)
The measuring method according to Wenner determines the soil resistivity down to a
depth of approximately the distance "a" between two earth spikes. By increasing "a",
deeper strata can be measured and checked for homogeneity. By changing "a" several
times, a profile can be measured from which a suitable earth electrode can be
determined.
According to the depth to be measured, "a" is selected between 2 m and 30 m. This
procedure results in curves depicted in the graph below.
1
2
Soil restivity ρE
A
Distances of Probe
3
edw021.eps
Curve 1: As ρE decreases only deeper down, a deep earth electrode is advisable.
Curve 2: As ρE decreases only down to point A, an increase in the depth deeper
Curve 3: With increasing depth ρE is not decreasing: a strip conductor electrode is
advisable.
As measuring results are often distorted and corrupted, for example, by
underground pieces of metal and underground aquifers, a second
measurement, in which the spike axis is turned by an angle of 90 °, is
always advisable (see graph below).
90°
E
ES
S
H
Measurement of Resistances
Resistance Measurement (R~)
This measuring function determines the ohmic resistance between 0.02 Ω and 300 kΩ.
The measurement is done with ac voltage. For measurements of very low resistances a
compensation of the connecting leads is suggested (see Compensation of Measuring Lead Resistance).
3. In this mode, all settings and LIMIT values available can be called with "DISPLAY
MENU" and the measuring frequency can be set.
4. Press "START TEST" button.
5. Read out measured value.
Resistance Measurement (R)
In this measuring mode all resistances from 0.02 Ω to 3 kΩ can be measured with dc
voltage and automatic polarity reversal as per EN61557-5.
To achieve highest accuracy 4-pole measurements are possible. To balance the
extension lead, a compensation has to be done.
Figure 13. Resistance Measurement (R)
edw024.eps
1. Connect instrument as shown in Figure 13.
2. Turn central rotary switch to position "R".
3. In this mode, all settings and LIMIT values available can be called with "DISPLAY
MENU".
Warning
Before starting a measurement, bring plant or test object to off or deenergized circuit condition. With an external voltage >3 V, the
measurement will not start.
Warning
Due to the high measuring current, inductive loads can cause lethal
induced voltages during disconnection from the measuring circuit.
4. Start measurement with "START TEST" button. First, "R1" with positive voltage is
measured on jack "E". After releasing the "START TEST" button "R
with negative voltage on jack "E". The respectively higher measured value is
displayed first.
5. The second measured value can be called with "DISPLAY MENU". If the set limit
value (R LIMIT) is exceeded the limit can also be displayed.
Compensation of Measuring Lead Resistance
1. Call display of RK with button "DISPLAY MENU".
2. Short circuit measuring lead as shown in Figure 14.
" is measured
2
3. Press "START TEST" button. Value R
is stored after the release of the "START
K
TEST" button, the display jumps back to voltage measurement. Thereafter, R
subtracted from the actual measured value. Turning the central rotary switch for a
short moment deletes the line compensation again.
Figure 14. Compensation of Measuring Lead Resistance
How to Change All Data Settings with Personalized CODE
With this function (FM, UM-Limit, Limit, beeper, ratio, R*) limit and set values can be
programmed which keeps them in memory even if the instrument is switched ON/OFF.
This feature enables the operator to create an instrument setup with customer defined
settings according to the specific need.
Table 7 shows the settings that can be made only in the respective functions:
Table 7. Data Settings
Function Parameter Setting range Standard presetting
F
RE 3pole UM 48 V/20 V 48 V
R
and LIMIT On / Off Off
R
RE 4pole (warning sound) On/Off Off
R* On/Off Off
F
RE 3pole UM 48 V/20 V 48 V R
and I ( ratio ) 80 ... 1200 1000
RE 4pole LIMIT On/Off Off R
(warning sound) On/Off Off
R* On/Off Off
F
R
R~ LIMIT On/Off Off R ~ LIMIT 0.000 Ω ... 999 kΩ 999 kΩ
R
2pole RK 0.000 Ω ... 29.99 Ω 0.000 Ω
and LIMIT On/Off Off
4pole R LIMIT 0.000 Ω ... 9,99 kΩ 9.99 kΩ
1. Press all 4 keys simultaneously and move central selector from OFF to the desired
measuring mode.
The display shows "C _ _ _".
2. Now enter the CODE number. Any three-digit number can be entered.
Note
Once a CODE has been entered, all subsequently programmed values can
only be changed after entering the CODE number. Once a "CODE" has
been entered, it cannot be erased or changed unless it is known. Be sure to
record your personal "CODE" and store in a safe location.
3. Inputting the code is done by means of the "CHANGE ITEM" and "SELECT" keys.
4. Pressing the "DISPLAY MENU" key completes input.
The CODE is now stored, and the display shows "C ON ".
5. If the display "C ON" is acknowledged by pressing "DISPLAY MENU", the first
parameter of the selected measuring function is displayed and can be changed with
the "CHANGE ITEM" and "SELECT" keys.
a. The changed value is stored by pressing the "DISPLAY MENU" key.
b. Pressing the "START TEST" key exits the setting program.
Note
If the limit values required by regulations are changed incorrect, erroneous
test results may be displayed.
To delete a code:
1. Press all 4 keys simultaneously and move central selector from OFF to any
measuring mode.
The display shows " C _ _ _ ".
2. Now enter the existing CODE number.
3. Inputting the code is done by means of the "CHANGE ITEM" and "SELECT" keys.
Pressing the "DISPLAY MENU" key completes input.
4. Display shows "C ON". In the "C ON" state the CODE function can be disabled by
pressing the "CHANGE ITEM" key. The display then shows "C OFF".
5. If this display is acknowledged by pressing the "DISPLAY MENU" key, the user code
and all changes of the limit values are erased. The original default values are
restored into memory.
6. Now a new CODE number may be programmed and used for setting new
parameters.
Export Stored Data to PC
Test data is automatically stored for all tests as a .csv file. Table 8 (continued on page
40) is an example of the .csv file.
To export data from the Tester to a PC:
1. Connect the USB cable from the Tester to the PC.
2. Use Windows Explorer on the PC to find new EGT drive in the Devices list.
3. Locate the Data.csv file on the EGT drive.
4. Use the standard PC tools to copy the file to a new location.
Table 8. Sample .CSV File for Logged Data
Mode
Measurement
1 15th Oct 2013 20:13:55 3-pole RE 48 V 128 Hz 0.0 V
2 15th Oct 2013 20:15:55 4-pole RE 48 V 128 Hz 0.0 V
3 15th Oct 2013 20:17:15 3-pole Selective 48 V 128 Hz 0.2 V
4 15th Oct 2013 20:21:10 4-pole Selective 20 V 111 Hz 0.0 V
5 15th Oct 2013 20:23:25 2-pole AC Resistance 48 V 128 Hz 0.2 V
6 15th Oct 2013 20:24:48 2-pole DC Resistance 48 V NA 0.2 V
7 10th Nov 2013 20:24:48 4-pole Re 48 V 111 Hz 0.0 V
8 10th Nov 2013 20:28:48 4-pole Selective 48 V 128 Hz 0.0 V
If used and treated properly, the instrument needs no maintenance. To clean the
instrument, use only a moist cloth with some soap water or soft household detergent or
spirit. Avoid aggressive cleaning agents and solvents, such as trilene or chlorothene.
Service work must only be undertaken by trained qualified staff.
In all repair work care must be taken that the design parameters of the instrument are not
modified to the detriment of safety, that assembled parts correspond to the original
spares and that they are reassembled properly (factory state).
To prevent possible electrical shock, fire, or personal injury:
•Use only specified replacement parts.
•Have an approved technician repair the Product.
•The battery door must be closed and locked before you operate
the Product.
•Replace the batteries when the low battery indicator shows to
prevent incorrect measurements.
Earth/Ground Tester
Maintenance
Warning
•Batteries contain hazardous chemicals that can cause burns or
explode. If exposure to chemicals occurs, clean with water and get
medical aid.
•Remove the input signals before you clean the Product.
For safe operation and maintenance of the Product:
•Repair the Product before use if the battery leaks.
•Be sure that the battery polarity is correct to prevent battery
30.0 Ω…299.9 Ω 0.1 Ω ± (2 % of rdg +2 digit) ± (5% of rdg +5 digit)
0.300 kΩ…2.999 kΩ 1 Ω
3.00 kΩ…29.99 kΩ 10 Ω
30.0 kΩ…299.9 kΩ 100 Ω
Measuring time: typical 8 seconds with a fixed frequency
30 seconds maximum with AFC and complete cycle of all
measuring frequencies
Additional error because of probe
and auxiliary earth electrode
resistance:
Measuring error of RH and RS: typical 10 % of
Maximum probe resistance: ≤1 M Ω
Maximum auxiliary earth electrode
resistance: ≤1 M Ω
RR
SH
R
E
)2000(
Ω+
++
HsE
6
−
+××
digits
5%1025.1
If after a measurement of probe, auxiliary earth electrode, and earthing resistance, a
measurement error of higher than 30 % is assumed because of the influencing conditions, the
display shows a warning symbol and a notice that R
or RH are too high.
S
RH with Umeas = 48 V RH with Umeas = 20 V Resolution
Measuring sequence: approximately 2 measurements/s
Earth/Ground Tester
Specifications
Measuri
Maximum interferen
ng time: typical 4 seconds includes reversal of polarity (2-pole or
4-pol
e)
ce voltage: ≤3 V ac or dc, with higher voltages measurement will not
be started
Maximum inductivity: 2 Henry
Maximum overload: U
= 250 V
rms
Compensation of Lead Resistance (RK)
Compensation of lead resistance (RK) can be switched on in functions RE 3pole, RE 3pole ,
R~, and R 2pole
Formation of measured value: R
= R
display
* Value of setpoint entry RK = 0.000 Ω, variable from 0.000…29.99 Ω by means
of measuring adj
measured
- R
compensated
ustment.
*
Stakeless Ground Loop Measurement ()
Resolution Measurement range AccuracyOperating Error
0.001 to 0.1 Ω0.020 Ω to 199.9 Ω ±(7% rdg + 3 d) ±(10% rdg + 5 d)
Measuring principle: Stakeless measurement of resistance in closed loops using two current
clamps
Measurement voltage: Um = 48 V ac (primary)
Measurement frequency: 128 Hz
Noise current (I
): max I
ext
= 10 A (ac) (Ra < 20 Ω)
ext
max
= 2 A (ac) (Ra > 20 Ω)
I
ext
The information about stakeless ground loop measurements is only valid when used in
conjunction with the recommended current clamps at the minimum distance specified.