Earth/Ground Tester
Users Manual
®
1625
January 2006
© 2006 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.
LIMITED WARRANTY AND LIMITATION OF LIABILITY
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 enduser 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.
Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands
11/99
Table of Contents
Title Page
Introduction .......................................................................................... 1
Models and Accessories........................................................................ 3
Safety Instructions ................................................................................ 4
Qualified Staff .................................................................................. 5
Setup..................................................................................................... 5
Unpacking......................................................................................... 5
Checking the Scope of Delivery ....................................................... 5
General ................................................................................................. 6
Additional Accessories ......................................................................... 6
Assembly .............................................................................................. 7
Description of Functions....................................................................... 7
Measurement of Interference Voltage (UST) ..................................... 8
Measurement of Interference Frequency (FST).................................. 8
Measurement of Earthing Resistance (RE)........................................ 9
Selective Measurement of Earthing Resistance (RE A) ................ 9
Resistance Measurement (R~) .......................................................... 9
Low Resistance Measurement (RF)................................................. 9
Checking for Correct Measuring Connection ................................... 9
Beeper............................................................................................... 9
LO-BAT............................................................................................ 10
Specifications........................................................................................ 10
Measurement of Interference Voltage DC + AC (UST) ..................... 13
Measurement of Interference Frequency (FST).................................. 13
Earthing Resistance (RE)................................................................... 13
Selective Measurement of the Earthing Resistance (REA)............ 17
Resistance Measurement (R~) .......................................................... 18
Resistance Measurement (RF)......................................................... 19
Compensation of Lead Resistance (RK) ............................................ 20
Description of the Operating Elements ................................................. 21
Description of Display Elements ...................................................... 23
Procedure of Measurements.................................................................. 24
POWER ON Functions ................................................................. 25
Operation ...................................................................................... 26
Checking of Correct Measuring Connection (Socket Allocation). 30
Safety Control Measurements....................................................... 31
i
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Users Manual
Measurement of Interference - Voltages and Frequencies................ 31
Measurement of Earthing Resistances.............................................. 32
Measurement of Soil Resistivity....................................................... 45
Measurement of Resistances ............................................................ 48
Changing of All Data Settings with Personalized CODE................. 51
Description of Displays........................................................................ 55
Care and Maintenance.......................................................................... 60
Replacing Batteries........................................................................... 61
Recalibration .................................................................................... 62
Storage.............................................................................................. 62
Specifications ....................................................................................... 64
Principle of Operation .......................................................................... 65
Purpose............................................................................................. 65
Operation.......................................................................................... 68
Applications ..................................................................................... 70
3-pole/4-pole Measurement of Earthing Resistance..................... 33
Measurement of Single Earth Electrode Resistances in
Mesh Operated Earthing Systems Using Selective Clamp
Method ......................................................................................... 36
3-pole/4-pole Measurement of Single Earth Electrode
Resistances ................................................................................... 37
Measurements on High Voltage Pylons........................................ 39
Correcting Clip-on Transformer Errors ........................................ 42
Compensation of Earth Electrode Connecting Lead..................... 44
Resistance Measurement (R~)...................................................... 48
Resistance Measurement (RF)..................................................... 49
Compensation of Measuring Lead Resistance.............................. 50
Storing a Code.............................................................................. 53
Deleting a Code............................................................................ 54
Settings on the Tester ................................................................... 69
Description of Displays................................................................ 72
ii
List of Tables
Table Title Page
1. Models and Accessories................................................. 3
2. Electrical Measurement Specifications .......................... 14
3. Description of Displays.................................................. 56
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iv
List of Figures
Figure Title Page
1. Fluke 1625 Earth/Ground Tester.................................... 2
2. Description of Functions ................................................ 8
3. Display ........................................................................... 10
4. Operating Elements........................................................ 21
5. Display Elements ........................................................... 23
6. Operational Modes ......................................................... 27
7. Measurement of Interference -
Voltages and Frequencies............................................... 32
8. Earthing Resistances Measurement - Method ................ 33
9. 3-pole/4-pole Measurement of Earthing Resistance -
Process............................................................................ 34
10. Earth Resistance - Maximum Permissible Value ........... 35
11. Measurement of Single Earth Electrode Resistances in
Mesh Operated Earthing Systems .................................. 36
12. 3-pole/4-pole Measurement of Single Earth
Electrode Resistances..................................................... 37
13. Measuring the Earthing Resistance without
Disengaging the Overhead Earth Wire........................... 40
14. Correcting Clip-on Transformer Errors.......................... 43
15. Compensation of Earth Electrode Connecting Lead ...... 44
16. Measurement of Soil Resistivity .................................... 45
17. Resistance Measurement (R~) ....................................... 48
18. Resistance Measurement (RF) ...................................... 49
19. Evaluation of Measured Value....................................... 50
20. Compensation of Measuring Lead Resistance ............... 51
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vi
Earth/Ground Tester
Introduction
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 ground test
instruments such as the 1625 which checks the effectiveness of connections to
the ground. The 1625 provides the perfect solution by combining the latest
technology into a compact, field-rugged and extremely easy to use instrument.
In addition to performing standard 3- 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 also incorporates
automatic frequency control (AFC) to minimize interference. Before measuring, the instrument identifies existing interference and selects a measurement
frequency to minimise its effect. The 1625 incorporates microprocessor controlled automatic measurements including checking probe hookup to ensure
that measurements are taken correctly. It measures all probe ground resistances
to ensure reliable, repeatable results. Probe resistance and auxiliary earth resistance are also measured and displayed.
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Notes
• The terms earth and earthing also refer to ground and grounding
and is used interchangeably throughout this manual.
• For stakeless earth resistance measurements, the EI-1625 must
be purchased. (The EI-1625 comes standard with the 1625 Kit).
Refer to Appendix A for a complete set of operating information
including specifications.
• Selective measurements are described in the main section of this
manual.
Figure 1 displays the Fluke 1625 Earth/Ground Tester:
EARTH / GROUND TESTER
1625
START
TEST
ST
H/C2
2
DISPLAY
MENU
CHANGE
ITEM
SELECT
Earth/Ground Resistance 300 k
RA
4
POLE
3
POLE
4
POLE
3
POLE
OFF
AC
Resistance
300 k
R
2
POLE
DC Low Resistance 3k
2
POLE
S/P2
R
4
POLE
ES/P1
E/C1
Figure 1. Fluke 1625 Earth/Ground Tester
edw001.eps
Earth/Ground Tester
Models and Accessories
Models and Accessories
Table 1 lists the models and accessories.
Table 1. Models and Accessories
Description Item/Part Number
Earth Ground Tester - Basic
(Includes manual, 2 leads and 2 clips)
Earth Ground Tester - Fully Loaded
(Includes manual, 2 leads and 2 clips,
ES162P4, EI-1623)
Service Replacement Kit
(Includes 2 Leads, 2 Clips)
Stake Set for 3 Pole Measurement
(Includes three stakes, one 25 m cable
reel, one 50 m cable reel)
Stake set for 4 Pole Measurement
(Includes four stakes, two 25 m cable
reels, one 50 m cable reel)
Selective/Stakeless Clamp Set for
1625. (Includes EI-162X and EI162AC and 2-3 wire adapter cable)
Clip-on Current Transformer (sensing)
with shielded cable set
Shielded Cable (Used w/EI-162X
Clamp)
Clip-on Current Transformer (inducing) EI-162AC
12.7 Inch (320mm) Spilt Core Transformer
2-3 Wire Adapter Cable for 1625 for EI162AC Current Transformer
Earth Stake 2539121
Cable Reel w/25m Wire 2539100
Cable Reel w/50m Wire 2539117
1625 Users Manual 2560348
Fluke-1625
Fluke-1625 Kit
Fluke-162x-7001
ES-162P3
ES-162P4
EI-1625
EI-162X
2539195
EI-162BN
2577171
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Users Manual
Safety Instructions
W Warning
This measuring equipment is only to be operated by qualified staff and in accord with its technical data in compliance with the safety precautions and instructions set forth
below. In addition, use of this equipment requires compliance with the legal and safety instructions pertaining to
the specific application in question. Similar precuations
apply to the use of accessories.
Caution
Operation of electrical equipment inevitably causes certain
parts of such equipment to carry dangerous voltage. Noncompliance with precautions may therefore cause major
physical or material damage.
Fault-free and reliable operation of this instrument requires suitable transport
and storage, setting-up and assembly, as well as care in operation and maintenance.
If there is reason to believe that risk-free operation is no longer possible, the
instrument should be switched off immediately and protected against accidental restarting. Risk-free operation shall be deemed to be no longer possible if
and when the instrument
• shows visible damage,
• fails to work in spite of functioning batteries,
• has been exposed for some time to unfavorable conditions ( e.g. stor-
age beyond the permissible climatic limits without adaptation to the
ambient climate, dewing etc.),
• has been exposed to major strain during transport ( e.g. been dropped
from some height without visible external damage etc.), or
• shows " E1 ... E5 " on the display.
4
Earth/Ground Tester
Setup
Qualified Staff
Consists of persons familiar with the setting up, assembly, starting up and operation of the product and possess the qualifications required for such activities, such as
• training, instruction and/or authorization to perform the following op-
erations on circuits and equipment according to safety engineering
standards: switching on and off, disconnecting, earthing/grounding,
labeling;
• training or instructions according to safety engineering standards in
the care and main tenance of adequate safety equipment.
• training in rendering first aid.
Setup
Unpacking
Check delivery for damage during transport. Keep the packing material for
later transport and check scope of delivery.
Checking the Scope of Delivery
Upon unpacking immediately check the accessories for missing parts. The accessories supplied are listed on page 2.
Caution
Although the instrument is easy to operate please read
these operating instructions carefully for safety reasons
and in order to make optimum use of the instrument.
The measuring functions are only all activated when the instrument is connected.
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General
Microprocessor controlled universal earth resistance meter with fully automated measuring frequency selection process as well as automatic testing of
probe- and auxiliary earth electrode resistances and possible interference voltages as per 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 3pole, 4pole, (R
)
ST
)
ST
)
S
)
H
) with or without
E
using the external clip-on current transformer for selective measurement of single earthing branches in mesh operated earthing systems
A
• Resistance measurement 2pole with AC voltage (R~)
• Resistance measurement with DC voltage 2pole, 4pole, (RF)
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 accoustical
confirmation/error message and with the code programmable and customer
defined special functions, e.g. measuring voltage 20 V (for agricultural systems), earthing impedance R* (measuring frequency 55 Hz) switched on or off
etc., these instruments are individually programmable for use as a simple meter
as well as a high end fully automated measuring device.
Additional Accessories
An external current transformer with a transformation ratio between 80 and
1200:1 for the measurement of a single branch in mesh operated earthing systems is available as an option and enables the user to measure on high voltage
pylons without seperating the overhead earth wires or earth strips at the bottom
of the pylons and also to measure lightning protection systems without seperating the individual lightning protection wires.
6
Earth/Ground Tester
Assembly
Assembly
The instrument is made up of two parts:
1. The base part which contains the measuring electronics.
2. The protective housing.
The functions are selected with the central rotary switch. Four rubber buttons,
which start measurements, read out supplementary measuring values and select
special functions, are located on the left hand side of the front panel. This design enables quick and clear one-hand operation.
The measured values are displayed on a liquid crystal display with correct
decimal point and unit. Various additional special characters indicate measuring mode, operating condition and error messages.
The auxiliary power supply consists of 6 x 1.5 V batteries (IEC R6 or LR6 or
type AA).
This device has been developed, designed and manufactured in compliance
with quality system DIN ISO 9001.
Description of Functions
The following flowchart presents a description of the functions of the 1625
Earth/Ground Tester.
7
1625
Users Manual
EXT
H
S
ES
E
Switching
Voltage
measurement
ADC
Comp
Current
measurement
Processor
Relais
driver
Source
driver
Rotary selector
switch buttons
LCD
Undervoltage
detection
Display
Supply
voltage
edw003.eps
Figure 2. Description of Functions
Measurement of Interference Voltage (UST)
Fullwave rectification for DC and AC (DC without operational sign, AC signal
sinus calibrated for r.m.s. values). If limit values are exceeded no measurement
will be started.
Measurement of Interference Frequency (FST)
For interference voltage >1 V its frequency is derived from the period time.
8
Earth/Ground Tester
Description of Functions
Measurement of Earthing Resistance (RE)
The earthing resistance is determined by a 3- 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).
Selective Measurement of Earthing Resistance (RE
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.
A
)
Resistance Measurement (R~)
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).
Low Resistance Measurement (RF)
The resistance is determined by DC current and voltage measurement. 2- 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.
Checking for Correct Measuring Connection
The processor 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 or acoustical signal.
Beeper
The built in beeper has two functions:
1. Giving messages if set limit values are exceeded.
2. Indicating dangerous conditions or maloperation.
Controlling is done by means of the microprocessor.
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Users Manual
LO-BAT
Supervision of the battery charge status is done with a comparator circuit. Via
microprocessor, a drop in battery capacity down to typ. 10 % of its specified
value is indicated on the display with symbol LO-BAT.
Specifications
General: Microprocessor controlled, fully automated earth
measuring instrument with additional functions
Measuring function: interference voltage and frequency, earthing resis-
tance 3- and 4-pole with / without clip-on current
transformer, resistance 2-pole with AC, 2- and 4-pole
with DC
Display
(see Figure 4):
ST
4 digit (2999 Digit) - 7 segment liquid crystal display,
digit size 18 mm with supplementary signs and active
illumination.
edw004.eps
Figure 3. Display
10
Earth/Ground Tester
Specifications
Operation: Central rotary switch and function keys
Working temperature range: -10 °C … +50 °C
Operating temperature range: 0 °C … +35 °C
Nominal temperature range: 18 °C … +28 °C
Storage temperature range: -30 °C … +60 °C
Note
The chart of four temperature ranges for the instrument exist to satisfy European Standards requirements; the instrument can be used
over the full Working temperature range by using the temperature coefficient to calculate accuracy at the ambient temperature of use.
Temperature coefficient: ± 0.1 % of range / Kelvin
Operating errors: refer to operating temperature range and RH
< 20 RE, RS < 100 RE
The maximum percentage operating error within the measurement range does
not exceed ± 30 % with the measured value as fiducial value, as determined in
accordance with TABLE 1.
The operating error applies under the rated operating conditions given in
IEC1557-1 and the following:
• injection of series interference voltages with system frequencies of
400 Hz, 60 Hz, 50 Hz, 16
2
/3 Hz or with d.c. voltage respectively
across the terminals E (ES) and S. The r.m.s. value of the series interference voltage shall be 3 V;
• resistance of the auxiliary earth electrode and of the probes: 0 to 100 x
but ≤ 50 kΩ;
R
A
• system voltages between 85 % and 110 % of the nominal voltage and
between 99 % and 101 % of the nominal system frequency for measuring equipment with a mains supply and/or measuring equipment deriving its output voltage directly from the distribution system.
Limits of error: refer to nominal temperature range
Climate class: C1 (IEC 654-1), -5 °C...+45 °C, 5 %...95 % RH
Type of protection: IP 56 for case, IP 40 for battery door according to
EN 60529
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Users Manual
Max voltage:
Urms = 0 V
Sockets ” E ES S H " to each other in any com-
EMC (Emission Immunity):
Quality standard: developed, designed and manufactured to comply
External field influence:
Auxiliary power: 6 x 1,5 V alkali-manganese-batteries (IEC
Battery life span: with IEC LR6/type AA: typ. 3000 measurements
with IEC LR6/type AA : typ. 6000 measurements
Dimensions: 240 mm (W) x 220 mm (D) x 90 mm ( H )
Weight: ≤ 1.1 kg without accessories
Wsocket A to socket EFGH
bination, max. Urms= 250 V (pertains to misuse)
IEC 61326-1:1997 Class A
with DIN ISO 9001
complies with DIN 43780 (8/76)
LR6 or type AA )
(RE+R
(RE + R
≤ 1 kΩ)
H
>10 kΩ)
H
≤ 5.5 kg incl. accessories and batteries in carrying
case
Case material: NORYL, shock -and scratch proof thermoplast
12
Earth/Ground Tester
Specifications
Measurement of Interference Voltage DC + AC (UST)
Measuring method: fullwave rectification
Measuring
Range
1…50 V 0.0…50 V 0.1 V DC/AC
Display
Range
Resolu-
tion
Frequency
Range
45…400 Hz
sine
Limits of Er-
ror
± (5% of
reading +5
digit)
Measuring sequence: approx. 4 measurements /s
Internal resistance:
Max. overload:
approx. 1.5 MΩ
U
= 250 V
rms
Measurement of Interference Frequency (FST)
Measuring method: Measurement of oscillation period of the interfer-
ence voltage
Measuring
Range
16.0 … 400
Hz
Display Range Resolution Range
16.0…299.9…99
9 Hz
0.1 … 1 Hz 1 V …
50 V
Limits of
Error
± (1% v. mv
+2 digit)
Earthing Resistance (RE)
Measuring method: current and voltage measurement with probe
as IEC61557-5
Open circuit voltage: 20 / 48 V, AC
Short circuit current: 250 mA AC
Measuring frequency: 94 , 105 , 111 , 128 Hz selected manually or
automatic.(AFC) 55 Hz in function R*
Noise rejection: 120 dB ( 16 2/3, 50 , 60, 400 Hz )
Max. overload: U
13
= 250 V
rms
1625
Users Manual
Intrinsic Er-
ror or Influ-
ence Quan-
tity
Table 2. Electrical Measurement Specifications
Requirements
Reference Con-
ditions or Speci-
fied Operating
Range
Designation
Code
or Test in Ac-
cordance with
the Relevant
Parts of
IEC 1557
Type
of
Test
Intrinsic error Reference condi-
A Part 5, 6.1 R
tions
Position Reference posi-
E1 Part 1, 4.2 R
tion
± 90°
Supply voltage
At the limits
stated by the
E2 Part 1, 4.2,
4.3
manufacturer
Temperature 0 °C and 35 °C E3 Part 1, 4.2 T
Series interference volt-
See 4.2 and 4.3 E4 Part 5, 4.2,
4.3
age
Resistance
of the probes
and auxiliary
0 to 100 x R
but ≤ 50 kΩ
A
E5 Part 5, 4.3 T
earth electrodes
System frequency
99 % to 101 % of
the nominal fre-
E7 Part 5, 4.3 T
quency
System voltage
85 % to 110 % of
the nominal volt-
E8 Part 5, 4.3 T
age
R
T
Operating
error
14
Part 5, 4.3 R
282726252423222
15,1( EEEEEEEEAB +±=
1
Earth/Ground Tester
Specifications
A = intrinsic error
En = variations
R = routine test
T = type test
[]
%B ±=
B
valuefiducial
100% x
Measuring
Range
0.001 Ω...2.999 Ω 0.001 Ω
3.00 Ω...29.99 Ω 0.01 Ω
0.020 Ω 30.0 Ω...299.9 Ω 0.1 Ω
300 kΩ 0.300 kΩ...2.999 kΩ 1 Ω
3.00 kΩ...29.99 kΩ 10 Ω
30.0 kΩ...299.9 kΩ 100 Ω
Display Range Resolution
Instrinsic
Error
± ( 2 % of
mv +2 digit )
Max. Op-
erating
Error
± ( 5% of
mv +5
digit )
Measuring time: typ. 8 sec. with a fixed frequency
30 sec. max. with AFC and complete cycle of all
measuring frequencies
Additional error because of
probe-and auxiliary earth
electrode resistance:
Measuring error of RH and
RR
SH
R
E
typ. 10 % of
)2000(
Ω+
RRR ++
6
−
HsE
+××
digits
5%1025.1
RS:
Max. probe resistance: ≤ 1 M Ω
Max. auxiliary earth elec-
≤ 1 M Ω
trode resistance:
Automatic check if error is kept within the limits required by IEC61557-5.
If after a measurement of probe-, auxiliary earth electrode- and earthing resistance, a measurement error of higher than 30 % is assumed because of the in-
15
1625
R
Users Manual
fluencing conditions (see diagramm), the display shows a warning symbol W
and a notice that RS or RH are too high.
F
%0001
%001
%01
%1
0
%1,
1 01
k
1 00
k01
3
k001
0001000
E
00
H
=R/R
3
0
01
3
0
01
3
1
3,0
S
M
1
edw005.eps
Automatic switchover of measuring resolution in dependence to auxiliary earth
electrode resistance R
:
H
RH with Umeas = 48 V RH with Umeas = 20 V Resolution
< 300 Ω < 250 Ω 1 mΩ
< 6 kΩ < 2,5 kΩ 10 mΩ
< 60 kΩ < 25 kΩ 100 mΩ
< 600 kΩ < 250 kΩ 1 Ω
16
Earth/Ground Tester
Specifications
Selective Measurement of the Earthing Resistance
(R
A
)
E
Measuring method: Current and voltage measurement with probe as per
EN61557-5 and current measurement in the individual
branch with additional current transformer (patent applied for).
Open circuit volt-
20 / 48 V AC
age:
Short circuit current: 250 mA AC
Measuring frequency:
94, 105, 111, 128 Hz selected manually or automatically (AFC), 55 Hz (R
*
)
Noise rejection: 120 dB (16 2/3 , 50 , 60 , 400 Hz)
Max. overload: max. Urms = 250 V (measurement will not be started)
Measuring
Range
0.001...2.999 Ω 0.001 Ω
3.00...29.99 Ω 0.01 Ω
0.020 Ω... 30.0...299.9 Ω 0.1 Ω
30 kΩ 0.300...2.999 kΩ 1 Ω
3.00...29.99 kΩ 10 Ω
Display Range Resolution
Intrinsic
Error *
± (7 % of
m.v. +2
digit)
Operating
Error *
± (10% of m.v.
+5 digit)
* With recommended current clamps / transformers.
Additonal error because
of probe- and auxiliary
earth typ.electrode resis-
RR
R
SH
ETOTAL
)2000(
Ω+
6
−
+××
digits
5%1025.1
tance:
Measuring error of RH
and RS:
Measuring time:
typ.of 10% of
RRR ++
HSETOTAL
typ. 8 sec. with a fixed frequency 30 sec.max.
with AFC and complete cycle of all measuring
frequencies
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1625
Users Manual
Minimal current in single
0.5 mA with transformer (1000:1)
branch to be measured:
Max. interference current
through transformer:
0.1 mA with transformer (200:1)
3 A with a transformer (1000:1)
Resistance Measurement (R~)
Measuring method: current and voltage measurement
Measuring voltage: 20 V AC, square pulse
Short circuit current: > 250 mA AC
Measuring frequency: 94, 105, 111, 128 Hz selected manually or auto-
matically (AFC)
Measuring
Range
0.001 Ω ... 2.999 Ω 0.001 Ω
3.0 Ω ... 29.99 Ω 0.01 Ω
0.020 Ω... 30 Ω ... 299.9 Ω 0.1 Ω
300 kΩ 300 Ω ... 2999 Ω 1 Ω
Display Range Resolution
Intrinsic
Error
± ( 2 %
of m.v.
+2 digit )
Operating
Errors
± ( 5% of m.v.
+5 digit )
3.0 kΩ ... 29.99 kΩ 10 Ω
30.0 kΩ ... 299.9 kΩ 100 Ω
Measuring time: typ. 6 sec.
Max. interference voltage: 24 V, with higher voltages measurement will not
be started
Max overload: Urms max. = 250 V
18
Earth/Ground Tester
Specifications
Resistance Measurement (RF)
Measuring method: current- voltage measurement as per IEC61557-4
possible
Open circuit voltage: 20 V DC
Short circuit current: 200 mA DC
Formation of measured
value:
with 4-pole measurement wires on H, S, ES can
be extended without additional error.
Resistances >1 Ω in wire E can cause additional
error of 5m Ω/Ω.
Measuring
Range
0.001 Ω ... 2.999 Ω 0.001 Ω
0.020 Ω 3.0 Ω ... 29.99 Ω 0.01 Ω
3 kΩ 30.0 Ω ... 299.9 Ω 0.1 Ω
300 Ω ... 2999 Ω 1 Ω
Display Range Resolution Intrinsic
Error
±( 2 % of
m.v. +2
digit)
Operating
Error
±( 5% of
m.v. +5
digit)
Measuring sequence: approx. 2 measurements/s
Measuring time: typ. 4 sec. incl. reversal of polarity (2 pole or 4
pole)
Max. interference voltage: ≤ 3 V AC or DC, with higher voltages measure-
ment will not be started
Max inductivity: 2 Henry
Max. overload: Urms = 250 V
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Users Manual
Compensation of Lead Resistance (RK)
Compensation of lead resistance (RK) can be
switched on in functions R
A, R~ , and R F 2pole
Formation of measured value:
3pole, RE 4pole
E
R
* Value of setpoint entry R
display
= R
measured
- R
compensated
*
= 0.000Ω, vari-
K
able from 0.000…29.99 Ω by means of
measuring adjustment.
20
Earth/Ground Tester
Description of the Operating Elements
Description of the Operating Elements
Figure 4 illustrates the operating elements described below.
6
EARTH / GROUND TESTER
2
3
4
START
TEST
DISPLAY
MENU
CHANGE
ITEM
SELECT
1625
Earth/Ground Resistance 300k
RA
4
POLE
3
POLE
4
POLE
3
POLE
OFF
AC
Resistance
300k
R
2
POLE
DC Low Resistance 3k
R
2
POLE
4
POLE
ES/P1
H/C2
S/P2
8
9
7
E/C1
10
5
1
rear side
12
13
11
edw006.eps
Figure 4. Operating Elements
A Central rotary switch to select measuring function or switch ON/OFF
B "START TEST"-button to start the set measuring function.
C "DISPLAY MENU"-button to call corresponding supplementary values.
21
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Users Manual
D "CHANGE ITEM" button to change the set point entry values.
E "SELECT" button to select the digit to be changed.
F Display unit, liquid crystal digits, 18 mm high with automatic decimal
point as well as active illumination.
G Connecting socket H (auxiliary earth electrode) (4 mm ø) also usable
with safety measuring lead
H Connecting socket G (probe) (4 mm ø) also usable with safety measuring
lead.
I Connecting socket for an ext. clip-on current transformer (optional).
W Warning
No voltage permissable to sockets EFGH.
J Connecting socket F (earthing probe) (4 mm ø) also usable with safety
measuring lead. Potential pick off with 4-pole earthing measurement.
K Connecting socket E (earth electrode) (4 mm ø) also usable with safety
measuring lead.
W Attention
Do not open or close the instrument with force!
L Battery compartment for: 6 x IEC LR6 batteries or type AA batteries.
W Warning
Disconnect all leads before opening the instrument!
M Screws to fasten the battery compartment
22
Earth/Ground Tester
Description of the Operating Elements
Description of Display Elements
The display (Figure 5) is divided into four display elements:
1. Digital display of measured value
2. Measuring function field to display measuring function
3. Unit field: V, Ω, kΩ, Hz
4. Special characters for operator guidance
2 3
Figure 5. Display Elements
1
4
Description of display symbols:
U
Interference voltage (AC + DC)
ST
F
Frequency of interference voltage
ST
F
Frequency of measuring voltage
M
U
Measuring voltage limit 20/48 V
M
R
Earthing resistance
E
R
Auxiliary earth electrode resistance
H
R
Probe resistance
S
R
Compensation resistance
K
R
, R2 Low voltage measurement with polarity indication
1
edw008.eps
23
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Users Manual
R ~ AC- resistance
*
Earthing impedance (measuring frequency 55 Hz)
R
AFC Automatic-frequency-control
TEST Measuring sequence in process
LIMIT Limit value
> LIMIT Limit value exceeded
EFGH Socket recognition
B Recognition of current transformer socket
} Message of an exceeded limit with beeper
LO-BAT Battery voltage too low, replace batteries.
REMOTE Interface ( optional ) active - button operation locked
C Measuring circuit ( E-S,E-H ) interrupted or measured value
instable
W Warning
Refer to Operating Instructions.
Procedure of Measurements
W Warning
Use the instrument on voltage free systems only.
1. Set measuring function with the central rotary switch 1
2. Connect instrument without measuring lead connected START is
omitted
3. Start measurement with "START TEST" button.
4. Read out measured value.
For optimum performance and utilization of the device observe the following
points:
24
Earth/Ground Tester
Procedure of Measurements
POWER ON Functions
During switching on of the instrument with the central rotary switch it is possible to access certain operating conditions by pressing certain 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 "---") approx. 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"
during switching 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.
c) Prolonged displaytest
By keeping the "DISPLAY MENU" button pressed during switching 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 switch on sequence, the
number of 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
Date of calibration: M M . J J
Note
At delivery the date of calibration is set to 0.00. Only after the first
recalibration a proper date is indicated.
25
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Users Manual
e) Activation of display illumination
By keeping the "CHANGE ITEM" button pressed during the switch on sequence the display illumination is activated. Illumination fades away automatically if the instrument is switched to"Stand by" and, together with the instrument, is switched on again by pressing any button. The instrument is switched
off with ON/OFF on the central rotary switch exclusively.
Operation
The measuring functions have two initial operational modes: the Control loop
and the Measuring loop (see Figure 6).
26
Earth/Ground Tester
Procedure of Measurements
CONTROL LOOP
POWER ON
Function
SELECT MEASURING
FUNTION WITH
CENTRAL ROTARY
SWITCH
1 X DISPLAY
SET VALUE OR
VOLTAGE
MEASUREMENT
1 X CHANGE 1 X SELECT
QUICK
SWITCHOVER,
SET VALUE
DIGIT/DECIMAL POINT
SPOT SELECTION
ON/OFF
LIMIT
MEASURING LOOP
1 X START
MEASUREMENT
DISPLAY, MEASURED VALUE
OR SUPPLEMENTARY VALUE
1 X DISPLAY
1 X CHANGE
INCREASE SELECTED
SPOT (DIGIT/DECIMAL
POINT) BY 1
edw009.eps
Figure 6. Operational Modes
27
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Users Manual
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 contiuous loop. The "SELECT" button selects
the decimal point 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 parmeter setting has been finished the next display can be called with
"DISPLAY MENU" or the measurement can be started with "START TEST".
Depending on the selected function, the following parameters can be displayed
or changed:
Function Parameter Setting Range Remarks
U
F
RE
3pole
U
and RK 0.000 Ω ... 29.99 Ω in position RE
R
RE
4pole
Sound) is activated with
R* On/Off only if activated
display only
ST
display only
ST
FM (AFC/94/105/111/128) Hz
48 V/20 V selectable to 20 V
M
with CODE
3pole only *
LIMIT 0.000 Ω ... 999 kΩ only if activated
E
with CODE
}(warning On/Off only if R
CODE
with CODE
U ST display only RE
F ST display only
LIMIT
E
28
Earth/Ground Tester
Procedure of Measurements
A U
and RK 0.000 Ω ... 29.99 Ω in position RE
4pole
A
}(warning- On / Off only if RE LIMIT
sound) is activated with
R* On / Off only if activated
48 V/20 V selectable to 20 V
M
with CODE
3pole only *
I ( ratio ) 80 ... 1200 display only RE
RE LIMIT 0.000 Ω ... 999 kΩ only if activated
with CODE
CODE
with CODE
* (see Compensation of Earth Electrode Connecting Lead)
Function Parameter Setting Range Remarks
U
F
F
R~ RK 0.000 Ω ... 29.99 Ω
R ~ LIMIT 0.000 Ω ... 999 kΩ only if activated
}(warning- On / Off only if R ~ LIMIT
sound) is activated with
RF U
2pole F ST display only
and RK 0.000 Ω ... 29.99 Ω
4pole R LIMIT 0.000 Ω ... 9,99 kΩ only if activated
}(warning -
display only
ST
display only
ST
(AFC/94/105/111/128) Hz
M
with CODE
CODE
display only
ST
with CODE
On / Off only if R LIMIT is
sound)
activated with
CODE
29
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Users Manual
Measuring Loop
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).
Checking of Correct Measuring Connection (Socket Allocation)
The instrument implements an automatic check, corresponding to the measurement selected, to see if the correct input sockets are used.
The display symbols EFGH and B
as shown in 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
30
are assigned to a specific socket
Earth/Ground Tester
Procedure of Measurements
Safety Control Measurements
Before each measurement the instrument automatically checks the measuring
conditions and, while simultaneously displaying the kind of error, prevents
measurements from being started under the following conditions:
• excessive voltage on the sockets (> 24 V in RE and R~; > 3 V in
RF)
• wrong or incomplete connection
• Problems during the measuring sequence (display "E1 ... E5") see
display description in the section ‘Procedure of Measurements’.
• Battery voltage too low ( display LO-BAT )
Measurement of Interference - Voltages and Frequencies
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 intereference voltage is higher than 1 V. See Figure 7.
Bring central rotary switch in desired position, read out measured value of interference voltage, measured value of interference frequency is displayed with
"DISPLAY".
31
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Users Manual
START
TEST
DISPLAY
MENU
Earth/Ground Resistance 300k
4
POLE
CHANGE
ITEM
3
POLE
OFF
SELECT
EARTH / GROUND TESTER
1625
RA
4
POLE
3
POLE
Resistance
300k
2
H/C2
S/P2
AC
DC Low Resistance 3k
R
R
POLE
2
POLE
4
POLE
ES/P1
E/C1
Auxiliary
earth
Earth
Probe
electrode
electrode
>20 m >20 m
Figure 7. Measurement of Interference - Voltages and Frequencies
edw010.eps
Measurement of Earthing Resistances
This instrument is equipped with a 3 pole as well as a 4 pole resistance measurement which 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 seperating parts of the system.
To ensure most feasible interference suppression during measurements, the
instrumen t is equipped with 4 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
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.
*
) a measurement with a frequency
32
Earth/Ground Tester
Procedure of Measurements
To keep the instrument as simple as possible at the time of delivery, all special
functions, such as LIMIT input, BEEPER programming, measurement of
earthing impedance (R
*
) etc, are not activated at delivery. They can be activated with personalized user's code (see "Changing of all Pre-set Data with
Personalized Code"). Refer to Figure 8.
G
I
E
E
RE
E
U
Umeas.
I
S
S
RS
H
H
H
R
edw011.eps
Figure 8. Earthing Resistances Measurement - Method
3-pole/4-pole Measurement of Earthing Resistance
This measuring function measures earthing and earth dissipation resistances of
single earth electrodes, foundation earth electrodes and other earthing systems
by using 2 earth spikes. See Figure 9.
33
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Users Manual
START
TEST
DISPLAY
MENU
Earth/Ground Resistance 300k
4 POLE
CHANGE
ITEM
3 POLE
OFF
SELECT
EARTH / GROUND TESTER
1625
RA
4 POLE
3 POLE
Resistance
300k
2 POLE
H/C2
S/P2
AC
DC Low Resistance 3k
R
R
2 POLE
4 POLE
ES/P1
E/C1
4 pole
Auxiliary
earth
Earth
Probe
electrode
electrode
>20 m >20 m
Figure 9. 3-pole/4-pole Measurement of Earthing Resistance - Process
edw012.eps
1. Turn central rotary switch to position "RE 3pole" or "RE 4pole"
The instrument is to be wired according to picture and notices given
on the display.
A flashing of the sockets symbols EFGH or A, 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, probe- and earth electrode resistance, is implemented and finished with the display of the result R
3. Read out measured value R
4. Call R
and RH with "DISPLAY MENU".
S
E
.
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 area of earth electrode
and auxiliary earth electrode (also see “The Influence of Potential Gradient
areas on Earth Resistance Measurement”). 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.
34
Earth/Ground Tester
Procedure of Measurements
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
E
constant.
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 “Procedures of Measurement”, “Description of display”) after a test sequence, most likely it is caused
by strong interference signals (e.g. unsteady noise voltage).Nevertheless, to get
reliable values, the instrument offers the possibility of averanging over a
longer period.
1. Select a fixed frequency (see “Control loop” in “Operation”)
2. Keep the "START TEST" button pressed until the warning "measured
value unstable" disappears. Max. averaging time is approx. 1 min.
Evaluation of measured value:
Figure 10 shows the maximum permissible value of the Earth resistance which
will not exceed a permissible limit value, taking into account the maximum
usage error.
Desired Values
10
0
5
10
20
20
50
50
100
100
200
200
500
1000
1000
500
Measured Values
3000 3152
2000
2999
edw013.eps
Figure 10. Earth Resistance - Maximum Permissible Value
35
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Users Manual
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 (e.g. lightning protection system
with several electrodes or high voltage pylons with earth cabling etc.). 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). 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
RE
RE
1
RE
2
3
RE3 =
Figure 11. Measurement of Single Earth Electrode Resistances in Mesh
Operated Earthing Systems
G
I
Z
tr
U
A
meas.
I
3
=
U
V
RS
meas.
tr
U
meas.
Aux. Earth
Probe
Electrode
RH
I
.
Z
edw014.eps
36
Earth/Ground Tester
Procedure of Measurements
Errors of the current transformer can be corrected as described in “Correcting
Clip-on Transformer Error”.
3-pole/4-pole Measurement of Single Earth Electrode Resistances
See Figure 12.
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
Earth/Ground Resistance 300k
4 POLE
CHANGE
ITEM
3 POLE
OFF
SELECT
H/C2
S/P2
AC
Resistance
300k
DC Low Resistance 3k
RA
R
R
2 POLE
4 POLE
2 POLE
3 POLE
4 POLE
ES/P1
E/C1
4 Pole
Probe
Auxiliary
earth
electrode
Earth
electrode
>20 m >20 m
edw015.eps
Figure 12. 3-pole/4-pole Measurement of Single Earth Electrode Resis-
tances
Turn central rotary switch to position "A RE 3pole" or "A RE 4pole".
The instrument is to be wired according to picture and notices given on the
display.
A flashing of the sockets symbols EFGH or A, 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
“Changing of all Data Settings with Personalised CODE”)
37
1625
Users Manual
Note
The ratio that is preset from factory is correct for the EI162X sensing
clamp
Press "START TEST" button.
Now a fully automated test sequence of all relevant parameters like auxiliary
earth electrode, probe- and earth electrode resistance, is implemented and finished with the display of the result R
1. Read out measured value R
2. Call R
and RH with "DISPLAY MENU".
S
.
E
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 (see also 12.5). 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 “Description of Displays”,
Procedure of Measurements) after a test sequence, most likely it is caused by
strong interference signals (e.g. unsteady noise voltage). Nevertheless, to get
38
Earth/Ground Tester
Procedure of Measurements
reliable values, the instrument offers the possibility of averaging over a longer
period.
1. Select a fixed frequency (see "Control loop", Operation)
2. Keep the "START TEST" button pressed until the warning "measured
value unstable" disappears. Max. averaging time is approx. 1 min.
Measurements on High Voltage Pylons
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 seperation
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.
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 pre-
meas
sent resistances involved.
One part flows via pylon construction to the overhead earth wire and further to
the parallelly circuited pylon earthing resistances.
The other four current components (I
The addition of all currents result in a current I
... I4) flow via the individual pylon foots.
1
going through the earthing
E
resistance, i.e. 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 behaviour inversely proportional to the corresponding current components I
... I4. The feeding point of
1
the measuring current is to be left unchanged to avoid a change in the current
distribution.
39
1625
Users Manual
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
E
circuit of the individual equivalent resistances:
R
=
E
1
+++
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
Earth/Ground Resistance 300k
3
4
POLE
CHANGE
ITEM
3
POLE
OFF
SELECT
H/C2
S/P2
AC
Resistance
300k
DC Low Resistance 3k
RA
R
R
2
POLE
4
POLE
2
POLE
POLE
4
POLE
ES/P1
E/C1
1111
RRRR
4321
EEEE
4 Pole
Probe
>20 m >20 m
Figure 13. Measuring the Earthing Resistance without Disengaging the
edw016.eps
Overhead Earth Wire
1. Turn central rotary switch to position “ARE 3pole" or ARE
4pole". The instrument is to be wired according to picture and notices
given on the display.
Auxiliary
earth
electrode
A flashing of the sockets symbols EFGH or B, 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 Personalised CODE”)
40
Earth/Ground Tester
Procedure of Measurements
3. Press “START TEST” button
Now a fully automated test sequence of all relevant parameters like
auxiliary earth electrode, probe- and earth electrode resistance, is implemented and finishes with the display of the result R
4. Read out measured value R
5. Call R
and RH with “DISPLAY MENU”.
S
E
.
E
Notices 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 (see also “The Influence of Potential Gradient Areas
on Earth Resistance Measurement”). 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
R
has to be calculated:
E
R
=
E
of all pylon foots are determined, the actual earth resistance
Ei
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.
41
1625
Users Manual
Time average measurement:
If there is a warning "measured value unstable" (see "Description of displays",
Procedure of Measurement) after a test sequence, most likely it is caused by
strong interference signals (e.g. unsteady noise voltage).
Nevertheless, to get reliable values, the instrument offers the possibility of
averanging over a longer period.
1. Select a fixed frequency (see "Control loop", Operation)
2. Keep the "START TEST" button pressed until the warning "measured
value unstable" disappears. Max. averaging time is approx. 1. min.
Measuring Earthing Impedance with 55 Hz (R*)
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
E
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 RE positions, the earthing impedance R* is displayed before all other measured values.
Correcting Clip-on Transformer Errors
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 (approx. 1 Ohm - in the range you want
to correct) as described in the picture below.
42
Earth/Ground Tester
Procedure of Measurements
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
CHANGE
ITEM
SELECT
Earth/Ground Resistance 300k
RA
3
POLE
4
POLE
3
POLE
OFF
AC
Resistance
300k
R
2
POLE
4
POLE
DC Low Resistance 3k
R
2
POLE
4
H/C2
S/P2
POLE
ES/P1
E/C1
Figure 14. Correcting Clip-on Transformer Errors
edw017.eps
2. Turn central rotary switch to position "A RE 3pole".
3. Press "START TEST"-button and note result of RE value.
4. Connect clip-on transformer.
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
CHANGE
ITEM
SELECT
Earth/Ground Resistance 300k
RA
3
POLE
4
POLE
3
POLE
OFF
Resistance
300k
2
4
POLE
AC
R
POLE
DC Low Resistance 3k
2
POLE
H/C2
S/P2
R
4
POLE
ES/P1
E/C1
edw018.eps
5. Turn central rotary switch to position "A RE 3pole".
6. Press "START TEST" again.
If the thus measured value R
deviates from the RE value determined without
E
clip-on transformer by more than 5 %, adjust the clip-on transformation ratio
(tr) correspondingly:
)(
troldtrnew
E
×=
E
−
−
merontransforwithclipR
)(
meronTransfprpwithoutcliR
43
1625
Users Manual
Example:
Your clip-on transformer has a transformation ratio of tr = 1000:1. The measurement without clip-on transformer results in a value R
clip-on transformer a value of R
= 1.175 Ω is measured.
E
The deviation thus reads (1.175 - 0.983) Ω= + 0.192 Ω and referring to R
= 0.983 Ω . With a
E
=
E
0.983 Ω an error evolves as following:
Ω
192.0
%100 +=
×
Ω
983.0
%5.19
The new transformation ratio to be set calculates:
1000 =×=trnew
175.1
1195
983.0
Compensation of Earth Electrode Connecting Lead
If the line resistance to the earth electrode can not be ignored, a compensation
of the connecting lead resistance to the earth electrode is possible. Proceed as
described below:
Measuring process:
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
Earth/Ground Resistance 300k
RA
4
POLE
3
POLE
4
POLE
CHANGE
ITEM
3
POLE
OFF
SELECT
Figure 15. Compensation of Earth Electrode Connecting Lead
Resistance
300k
2
H/C2
S/P2
AC
DC Low Resistance 3k
R
R
POLE
2
POLE
4
POLE
ES/P1
E/C1
Auxiliary
Earth
electrode
earth
electrode
edw019.eps
1. Turn central rotary switch to position "RE 3pole".
2. Wire instrument according to picture.
44
Earth/Ground Tester
Procedure of Measurements
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 actual measured value.
K
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.
Measurement of Soil Resistivity
The soil resistivity is the geological and physical quantity for calculation and
design of earthing systems. The measuring procedure applied below 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 478496; 1915/16).
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
Earth/Ground Resistance 300k
RA
4
POLE
3
POLE
4
POLE
CHANGE
ITEM
3
POLE
OFF
SELECT
AC
Resistance
300k
R
2
POLE
DC Low Resistance 3k
2
POLE
H/C2
S/P2
R
4
POLE
ES/P1
E/C1
edw020.eps
Figure 16. Measurement of Soil Resistivity
45
1625
π
ρ
Users Manual
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 hammered in deeper than a maximum of 1/3 of
"a".
2. Turn central rotary switch to position "R
4pole".
E
The instrument is to be wired according to picture and notices given
on the display.
A flashing of the sockets symbols EFGH or B, points to an
incorrect or incomplete connection of the measuring lead.
3. Push "START TEST" button.
4. Read out measured value R
From the indicated resistance value R
.
E
, the soil resistivity calculates according
E
to the 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 approx. the distance "a" between two earth spikes. By increasing "a", deeper strata can be measured and checked for homogenity. 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.
46
Earth/Ground Tester
Procedure of Measurements
2
E
Soil restivity
Distances of Probe
1
3
A
edw021.eps
Curve 1: As ρE decreases only deeper down, a deep earth electrode is advis-
able
Curve 2: As ρE decreases only down to point A, an increase in the depth
deeper than A does not improve the values.
Curve 3: With increasing depth ρE is not decreasing: a strip conductor elec-
trode is advisable.
As measuring results are often distorted and corrupted by underground pieces
of metal, underground aquifers etc, a second measurement, in which the spike
axis is turned by an angle of 90 ° , is always advisable (see picture).
47
1625
Users Manual
O
90
E
ES
S
H
I
edw022.eps
Measurement of Resistances
Resistance Measurement (R~)
This measuring function determines the ohmic resistance between 0.001 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”).
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
CHANGE
ITEM
SELECT
Earth/Ground Resistance 300k
RA
3
POLE
4
POLE
3
POLE
OFF
AC
Resistance
300k
R
2
POLE
4
POLE
Figure 17. Resistance Measurement (R~)
DC Low Resistance 3k
R
2
POLE
4
H/C2
S/P2
POLE
ES/P1
E/C1
edw023.eps
1. Turn central rotary switch to position "R~".
48
Earth/Ground Tester
Procedure of Measurements
2. Connect instrument according to picture.
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 (RF)
In this measuring mode all resistances from 0.001 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.
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
CHANGE
ITEM
SELECT
Earth/Ground Resistance 300k
RA
3
POLE
4
POLE
3
POLE
OFF
AC
Resistance
300k
R
2
POLE
4
POLE
DC Low Resistance 3k
R
2
POLE
4
H/C2
S/P2
POLE
ES/P1
E/C1
edw024.eps
Figure 18. Resistance Measurement (RF)
1. Connect instrument according to picture.
2. Turn central rotary switch to position "RF".
3. In this mode, all settings and LIMIT values available can be called
with "DISPLAY MENU".
W Warning
Before starting a measurement bring plant or test object to
off or de-energized circuit condition! With an external voltage higher than 3 V measurement will not be started.
49
1625
Users Manual
W 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
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.
Evaluation of measured value:
Taking into account the maximum operating error, the diagrams show the
maximum admissable display values to be displayed so not to exceed the required resistance.
Measuring Range 29, 99 ... 299, 9 ... 2999 Ω
" is measured with negative voltage on jack "E".
2
Desired Values
10
0
5
20
10
Figure 19. Evaluation of Measured Value
20
50
50
100
100
200
200
500
1000
500
1000
Measured Values
Compensation of Measuring Lead Resistance
1. Call display of RK with button "DISPLAY MENU".
2. Short circuit measuring lead according to picture.
3. Press "START TEST" button. Value R
the "START TEST" button, the display jumps back to voltage measurement. Thereafter, R
is subtracted from the actual measured value.
K
50
is stored after the release of
K
3000 3152
2000
2999
edw025.eps
Earth/Ground Tester
Procedure of Measurements
Turning the central rotary switch for a short moment deletes the line
compensation again.
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
CHANGE
ITEM
SELECT
Earth/Ground Resistance 300k
RA
3
POLE
4
POLE
3
POLE
OFF
AC
Resistance
300k
R
2
POLE
4
POLE
DC Low Resistance 3k
R
2
POLE
4
H/C2
S/P2
POLE
ES/P1
E/C1
Figure 20. Compensation of Measuring Lead Resistance
edw026.eps
Changing of All Data Settings with Personalized CODE
With this function (FM, UM-Limit, Limit, beeper, ratio, R*, F*) limit- and set
values can be programmed which keeps them memorized even if the instrument is switched ON/OFF. This feature enables the operator to create an instrument set-up with customer defined settings according to the specific need.
Settings can only be made in the respective functions:
51
1625
Users Manual
Function Parameter Setting range
F
RE
3pole
R
and LIMIT On / Off Off
R
RE
4pole
R* On/Off Off
F
RE
3pole
A R
and I ( ratio ) 80 ... 1200 1000
RE
4pole
A R
}(Warning
R* On/Off Off
F
R
R~ LIMIT On/Off Off
R ~ LIMIT 0.000 Ω ... 999 kΩ 999 kΩ
(AFC/94/105/111/128) Hz AFC
M
UM 48 V/20 V 48V
0.000 Ω ... 29.99 Ω 0.000 Ω
K
LIMIT 0.000 Ω ... 999 kΩ 999 kΩ
E
}(Warning
sound)
(AFC/94/105/111/128) Hz AFC
M
UM 48 V/20 V 48V
0.000 Ω ... 29.99 Ω 0.000 Ω
K
LIMIT On/Off Off
LIMIT 0.000 Ω ... 999 kΩ 999 kΩ
E
sound)
(AFC/94/105/111/128) Hz AFC
M
0.000 Ω ... 29.99 Ω 0.000 Ω
K
}(Warning
sound)
On/Off Off
On/Off Off
On/Off Off
Standard
presetting
52
Earth/Ground Tester
Procedure of Measurements
R F
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
}(Warning
sound)
On/Off Off
Storing a Code
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. If an unknown "CODE" has been programmed, it can only be
read or erased by its author or manufacturer. Therefore note down
your personal "CODE" here.
CODE . . .
3. Inputing 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.
53
1625
Users Manual
6. The changed value is stored by pressing the "DISPLAY MENU" key.
7. 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.
Deleting 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. Inputing 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.
54
Earth/Ground Tester
Description of Displays
Description of Displays
Table 3. Description of Displays
Function Displays Condition Note
Before
"START"
ST
LO-BAT
edw027.eps
V
edw028.eps
edw029.eps
Stand by
position to
reduce
power
consumption
No or
incorrect
measuring
lead
connection
Battery
voltage too
low
Beeper on Acoustical
Turn rotary
switch or
push
button. All
measured
values
remain
stored
Apart from
voltage
measurement all
measuring
functions
are locked.
Replace
batteries.
warning if
limit is
exceeded.
edw030.eps
Legend: W= displayed flashing
55
1625
Users Manual
Function Displays Condition Note
Before
"START"
After
"START"
Apart from
voltage
measurement all
measuring
functions
ST
LIMIT
V
edw031.eps
Dangerous
AC - voltage > 50
V
are locked.
Rotary
switch in
inter-
Select correct posi-
tion.
mediate
position
edw033.eps
Probe re-
S
TEST
edw034.eps
sistance is
being
tested
Aux. current spike-
H
TEST
edw035.eps
resistance
is being
tested.
Wait for
test result.
Wait for
test result.
E
TEST
Legend: W= displayed flashing
56
edw036.eps
Earth resistance is
being
tested.
Wait for
test result.
Earth/Ground Tester
Description of Displays
Function Displays Condition Note
ST
V
Measuring
circuit of
earth- and
auxil. earth
electrode
edw037.eps
disconnected.
Check lead
connection
on earth
spikes
measuring
lead might
be defective.
ST
V
Measuring
circuit of
earth- and
probe electrode dis-
edw038.eps
connected.
Check lead
connection
on earth
spikes
measuring
lead might
be defective.
Max allowable error
H
LIMIT
K
edw039.eps
exceeded
because of
too high
sense or
aux earth
Try to
moisten
soil or
connect
2nd aux
earth spike
in parallel.
spike resistance.
After
"START"
Measuring
range ex-
E
k
ceeded.
Measured
value is
higher than
300 kΩ.
LIMIT
edw040.eps
Legend: W= displayed flashing
57
1625
Users Manual
Function Displays Condition Note
Display of
measured
E
value exceeds
LIMIT
edw041.eps
LIMIT.
Compensation
K
higher than
measured
LIMIT
edw042.eps
ST
value.
Wrong polarity on
Measured
value is
higher than
set LIMIT.
Delete
compensation or
switch instrument
ON/OFF.
Reverse
polarity.
jacks E
and ES.
edw043.eps
Measured
value in-
E
stable.
Unsteady
noise volt-
age. Try
time aver-
age meas-
urement.
edw044.eps
ST
Legend: W= displayed flashing
58
V
edw045.eps
Current in
external
transformer to
low.
Reduce
auxiliary
current
spike re-
sistance.
Earth/Ground Tester
Description of Displays
Function Displays Condition Note
No reactions to button
control etc.
After
"START"
E
Legend: W= displayed flashing
edw046.eps
edw047.eps
edw048.eps
edw049.eps
Operation
under
faulty conditions.
Reverse
orientation
of current
clamp or
"upwards"
current.
Checksum
of EE
PROM incorrect.
Hardware
malfunction (e.g.
current
overload).
Check batteries.
Switch
ON/OFF if
still faulty,
contact
service.
Reverse
clamp or
see note
on page
28.
Switch
ON/OFF if
still faulty;
The symbol may
appear
when using the
stakeless
measurement on
low resistance circuits.
59
1625
Users Manual
Function Displays Condition Note
ST
E
12MKH
REMOTE
LO-BAT
TEST
LIMIT
Legend: W= displayed flashing
edw050.eps
edw051.eps
edw052.eps
VmA
k
nFmH
edw053.eps
Hz
EE PROM
memory
access malfunction.
Internal
computation malfunction.
Thermal
overload.
Battery
voltage decreases at
measurement.
contact
service.
Cool thor-
oughly.
The internal
resistance of
the batteries
is too high
(worn out, low
temperature).
Replace batteries, warm
up instrument.
Care and Maintenance
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
60
Earth/Ground Tester
Care and Maintenance
detergent or spirit. Avoid aggressive cleaning agents and solvents (trilene,
chlorothene etc.).
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).
Caution
Before any maintenance, repair or parts replacement the
instrument must be disconnected from all voltage sources.
Replacing Batteries
Note
NiMH or NiCADcells 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 instrument is equipped with six 1.5 V batteries IEC RL 6 or type AA. If
after pressing the START-button all display-segments are lit (instrument resets, display-test) or if “LO-BAT” appears on display during a measurement
the batteries must be replaced or the accumulators must be recharged.
Caution
For replacement of batteries the measuring cable must be
disconnected, and the instrument switched off. Now the
two screws at the rear of the instrument can be loosened
with a suitable tool (screwdriver) and the battery recess
cover removed. When replacing batteries, mind the correct
polarity.
Always replace the complete set of batteries.
Note
For protection of the environment, please ensure proper disposal of
the batteries.
61
1625
Users Manual
Recalibration
This instrument exceeds the prescribed accuracies by multiples as it leaves the
factory. To maintain it in this state, we recommend a check at 1-year intervals.
Please contact the nearest sales or service center for this purpose.
As an extra service feature we offer you periodic checking and calibration of
your meters. You may order, for a fee, either company test certificates or test
certificates of the public calibration service at your option. These orders will
be carried out either generally or with additional test records (measuring
points) as ordered by you.
Service
If you suspect that the tester has failed, review this manual to make sure you
are operating it correctly. If the meter still fails to operate properly, pack I securely (in its original container if available) and forward it, postage paid, to the
nearest Fluke Service Center. Include a brief description of the problem. Fluke
assumes NO responsibility for damage in transit.
To locate an authorized service center, call Fluke using any of the phone numbers listed below:
USA: 1-888-99-FLUKE (1-888-993-5853)
Canada: 1-800-36-FLUKE (1-800-363-5853)
Europe: +31 402-678-2005
Japan: +81-3-3434-0181
Singapore: +65-738-5655
Anywhere in the world: +1-425-446-5500
Or, visit us on the World Wide Web: www.fluke.com. To register your prod-
uct, visit register.fluke.com
Storage
If the instrument is stored or remains unused for some time, the batteries
should be removed and stored separately to guard against damage by leaking
electrolyte.
62
Stakeless Earth/Ground Resistance Testing
Care and Maintenance
Appendix A
Stakeless Earth/Ground Resistance
Testing
Introduction
Stakeless testing provides the ground tester with the unique capability to measure individual ground resistances in multi-grounded systems using two clampon current transformers.
The use of ground stakes is not necessary.
Before this method was available, users were required to disconnect an individual ground path to be tested from other grounds to eliminate the influence
of parallel ground paths.
This was time consuming at the minimum and in many cases dangerous.
Once disconnected, the standard 3-pole/terminal ground testing method was
used which requires auxiliary earth stakes. In addition to consuming additional
time, finding suitable locations for the ground stakes can be difficult and in
some cases, impossible. The "stakeless" method of ground resistance testing
eliminates these problems and ideally complements the ground testers' standard testing methods.
63
1625
Users Manual
edw060.eps
Specifications
General: Adapter unit for use with ground testers in the mode: R
3 pole (Order No. EI-1625)
All information contained in this section exclusively refers to this application.
Principle: Ground testing without using earth stakes
for the probe and the auxiliary earth electrode.
Working temperature range –10 °C ... +55 °C.
Operating temperature range 0 °C ... +30 °C.
Storage temperature range
–30 °C ... +70 °C.
Quality standard: Developed, designed and manufactured to
comply with DIN ISO 9001.
64
D
E
Stakeless Earth/Ground Resistance Testing
Principle of Operation
Dimensions
Operating error*: ± (10% of m.v. + 5 digit).
Display range*:
Measuring frequency:
Measuring voltage: U
Measuring range*:
Resolution:
*when using: CT EI-162AC to induce voltage and
Recommended distance between CT's:
Total length of adaptercable 1,8 m, Length
of shielded cable to clamp-on CT 1,5 m.
0,010 Ω ... 130 Ω.
128 Hz.
=48 VAC (primary).
m
0,020 Ω ... 100 Ω.
.001... .1 ohm.
CT EI-162X to detect current.
10 cm.
Principle of Operation
Purpose
Testing the resistances of individual ground connections in systems with parallel ground connections (multi-grounded systems).
65
1625
Users Manual
Equivalent diagram
AC
Source
U
I
66
U
R
R
X
X
R
1
+=
1
21
R
2
+⋅⋅⋅⋅++
R
3
R
n-1
R
n
edw061.eps
111
RRR
n
Stakeless Earth/Ground Resistance Testing
Principle of Operation
If the parallel connection of resistors, R1...Rn is considerably lower than the
ground connection under test R
:
X
then
1
21
U
= is a reasonable approximation.
R
X
I
<<
111
⋅⋅⋅⋅++
RRR
n
R
X
The test voltage (U) is applied without disconnecting ground rod and/or the
direct electrical connection by means of a clamp-on current transformer and
the current detected by a second current transformer.
Voltage
U
Current
I
R
X
R
1
R
2
R
n-1
R
n
edw062.eps
After synchronous rectification of current and voltage the tester displays RX.
67
1625
Users Manual
Operation
Connect the adapter according to the diagram and the designations E, S and H
(C1, P1 and P2 for US-version) to the tester and to a current clamp.
EARTH / GROUND TESTER
1625
START
TEST
DISPLAY
MENU
CHANGE
ITEM
SELECT
Earth/Ground Resistance 300k
RA
3
POLE
4
POLE
3
POLE
OFF
4
POLE
AC
Resistance
300k
R
2
POLE
DC Low Resistance 3k
2
POLE
H/C2
S/P2
R
4
POLE
ES/P1
E/C1
Use the test cable contained in the set to connect the second current clamp to
the socket. Ensure that connections are in the correct polarity. Turn the rotary
switch of the tester to position
H
S
E
R
D 3 pole.
E
Black
EI-162AC
Red
EI-162X
edw063.eps
Note
Use only current transformers referred to in this manual.
Clamp both transformers around the ground conductor to be tested.
Note
Try to have a distance > 10 cm between the clamps for optimal results.
68
Stakeless Earth/Ground Resistance Testing
Principle of Operation
Erder
>10 cm
edw064.eps
Pushing the START-button will display the value of RE.
Note
In this particular mode the values of RH and RS have no meaning.
Settings on the Tester
Refer to the Operation section in the Testers instruction manual.
The rotary switch of the tester must be in the R
Set Test Voltage to 48 V (standard value)
- U
m
- R
Set compensation resistance to 0,000 Ohms
k
3 pole position.
E
- I Set transformer ratio to 1000 (standard value)
- R* Set to OFF (no meaning in this mode).
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Applications
Example1: Ground rod on power poles.
edw065.eps
Example 2: Tests on multi-grounded (inter-connected) systems:
Ground conductors are for example bonded to grids or concrete-footing
grounds and other conducting elements such as lightning protection systems or
frameworks.
In this case the resistances of individual ground paths are not of significance.
It must be tested if the resistance of the bonding is sufficiently low and reliable.
70
Stakeless Earth/Ground Resistance Testing
Principle of Operation
Lightning
Protection
M
Footing ground
Framework
edw066.eps
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Description of Displays
With stakeless ground testing some display combinations have certain significance.
Display Significance Note
E
edw067.eps
edw068.eps
Legend: W= displayed flashing
Polarity of
CT’s is reversed
Resistance
under test is
below measuring range
or adapter
cable is
plugged into
ground tester
incorrectly
Turn one
CT
Switch
on/off for
next test
72
Stakeless Earth/Ground Resistance Testing
Principle of Operation
Display
ST
edw069.eps
Legend: W= displayed flashing
V
Significance
Resistance
under test is
above
measuring
range
Note
73
Appendix B
Earthing Resistance
Introduction
Per definition, the earthing resistance consists of several individual resistances.
1. The resistance of connecting lead to earth electrode
2. The resistance of the actual earth electrode; earthing rod, earthing
plate, earthing strip, mesh earth electrode etc.
3. The dissipation resistance, the resistance between earth electrode and
soil potential.
As the connecting cable and the resistance of the earth electrode are negligibly
small after correct dimensioning, the earthing resistance dominantly dependends on the dissipation resistance. This shows that an accurate measurement of the dissipation resistance is necessary to determine the exact earthing
conditions for protective measures. As the dissipation resistance is not only
dependent on the specific soil resistivity, that is the resistance of the actual soil
( gravel, clay, granite ), but also significantly depents on the shape of the earth
electrode, a metrological check has to be made even if the position of the earth
electrode and the condition of the soil is well known.
For redimensioning of an earthing system, e.g. a lightning protection, an approximate calculation, according to the table below, is possible. As a basis for
this calculation the soil resistivity of the spot where the earth electrode is to be
installed has to be known.
74
Earthing Resistance
Principle of Operation
Type of
Soil
Soil Re-
sitivity
[ρE]
Earthing Rod m
Earthing Resistance (Ω)
Depth
Earthing Strip m
Ω.m 3 6 10 5 10 20
Moist
30 10 5 3 12 6 3
humus
soil,
moor soil,
swamp
Farming
100 33 17 10 40 20 10
soil,loam
y and
clay soils
Sandy
150 50 25 15 60 30 15
clay soils
Moist
300 66 33 20 80 40 20
sandy
soil
Dry
1000 330 165 100 400 200 100
sandy
soil
Concrete
*
1 : 5
Moist
400 160 80 40
500 160 80 48 200 100 50
gravel
Dry
1000 330 165 100 400 200 100
gravel
Stoney
30000 1000 500 300 1200 600 300
soil
Rock 10
7
- - - - - -
* for concrete mixtures 1 : 7 the values have to be increased by 24 %
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Soil Resistivity
ρ
E
The soil resistivity is the resistance measured between two opposing surfaces
of a cube of homogenous soil material with a lateral length of 1 meter. The unit
is Ωm (see picture)
A = 1 m
p =
L=1 m
2
A
.
(
m
)
R
L
E
edw054.eps
The soil resistivity significantly depends on the specific kind of material (farming soil, dry sand, moist sand, concrete, gravel etc.), but also depends on seasonal changes. Dry soil has a higher resistivity than moist soil and frozen
ground has a higher resistivity than dry, warm sand (see picture).
The two examples below show the change of resistivity during the course of
one year.
76
Earthing Resistance
Principle of Operation
28
24
20
E
16
12
Earth resistance R
8
4
0
0
Jan.
2
1
34
5
month
6
7 9 10 11 12
July
8
Dec.
edw055.eps
Temporal change of the earthing resistance of a conductor earth electrode
(earth strip, earth cable).
14
12
10
E
8
6
4
Earth resistance R
2
0
0
Jan.
1
2
3
4
5
month
6
July
7
8
9
10 11
Dec.
12
edw056.eps
Temporal change of the earthing resistance of a buried earth electrode (earth
pipe, earth plate)
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Measuring Method
The current voltage measuring method is based on the block diagram circuit
shown in the figure below.
UE
G
I
E
ES
E
R
E
U meas.
V
I
S
S
R
S
H
H
R
H
edw057.eps
An AC generator G feeds current I via earth electrode E (earth electrode resistance R
R
Voltage U
) and auxiliary earth electrode H (auxiliary earth electrode resistance
E
).
H
drops on earthing resistance RE (UE proportional to RE.) This volt-
E
age is picked up and measured by probe S. With the so called three wire circuit, the instrument sockets E and ES are connected to each other. In a four
wire circuit an separate cable is used to connect socket ES with the earth electrode.
With that, the voltage drop of the cable between socket E and earth electrode is
not measured. As the voltage measuring circuit has such a high impedance, the
influence by the probe resistance R
is neglectable within certain limits.
S
Thus the earthing resistance evolves
U
R =
and is independent from the resistance of the auxiliary earth electrode R
Meas
E
1
. The
H
generator runs at a frequency between 70 and 140 Hz.
It has to hold a minimum distance of 5 Hz to one of the nominal frequencies
between 16 2/3, 50 or 60 Hz and their harmonic waves. A frequency selective
filter adjusted to the generator frequency is inserted.
78
Earthing Resistance
Principle of Operation
The Potential Gradient Area
Around every earth electrode a so called potential gradient area develops during the flow of an electric current (see picture below).
U
U
S
U
E
If the voltage between the earth electrode and a probe with a distance "a" from
the earth electrode is measured, the value increases less with increasing distance. Once the voltage does not increase, the probe is levelled to earth potential F
that is, outside the potential gradient area.
E
It is the soil resistivity that mainly affects the diameter of the potential gradient
area. This means the diameters in soils with a bad conductivity are correspondingly wide (30 ... 60 m), soils with a good conductivity correspondingly narrow (10 ... 15 m).
E
60 m
40
edw058.eps
Determining the probe- and auxiliary earth electrode resistance provides information about the size of a possible potential gradient area. High resistances
lead to correspondingly large gradient areas and vice versa. In this context it
has to be taken into account that soils with a good conductivity and correspondingly small potential gradient areas result in a relatively steep voltage
shape and therefore in a relatively high step voltage. If necessary, such systems
have to undergo a potential check.
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The Influence of Potential Gradient Areas on Earth Resistance Measurement
To pick off the true voltage drop from the earthing resistance (= the resistance
between the earth electrode and the soil potential F
probe is set outside the potential gradient area of all connected earth electrodes
and the auxiliary earth electrode H.
G
U
S1
V
I1
E1
S1
S1
U
U
S2
V
I2
S2
E2
U
S2
U
I
G
F
E
) it is to be assured that the
E
U
S2
V
S3
U
S3
U
S4
V
S4
U
G
I
H
U
S4
edw059.eps
A probe positioned inside a potential gradient area leads to incorrect measuring
results. As it can be seen in the picture above, probe voltages U
probes S
and S2 deliver a value too low, which also means that the earthing
1
resistance appears to be lower than it actually is(low resistance). Probe S
U
on the other hand, picks up a value too high which indicates a worse (high
S4
and US2 of
S1
with
4
resistance) earthing conditions.
Only probe S
potential F
picks up the correct voltage between earth electrode and soil
3
.
E
For that reason it is advisable to repeat each measurement with repositioned
probes and only to regard a measurement as successful and accurate if several
subsequent measurements result in the same values.
Normally, a distance of 20 m to the earth electrode and to the probes to each
other is sufficient.
80
Earthing Resistance
Principle of Operation
Earth Impedance (R*) on High Voltage Transmission Lines
The earthings of transmission line pylons are interconnected via the overhead
earth wire.
This wire is not only ohmic. There is also inductivity and resistivity (L´, R´).
For calculation of the short circuit current this impedance at line frequency has
to be determined.
Inductivity and resistivity are known in most cases. Therefore the actual impedance can be calculated for each point of the line by a complex computation
considering individual pylon resistance. This (computation) has to be done for
each single pylon.
The earth impedance can be measured with this instrument.
The inductive portion of the impedance of the overhead wire is frequency dependent.
Accordingly, the measuring frequency applied by the tester has to be close to
the mains frequency in order to get correct readings.
For that reason ordinary testers using frequencies between 70 Hz and 140 Hz
show incorrect readings. This instrument measures with 55 Hz to be near
enough to 50 / 60 Hz line frequency but to avoid interference with them
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