Chauvin Arnoux C.A 6421 User manual

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CONTRÔLEUR DE TERRE

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EARTH TESTER

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ERDUNGSPRÜFER

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CONTROLLORE DI TERRA

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CONTROLADOR DE TIERRA

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C.A 6421

ENGLISH

User's Manual

1

i

English

Meaning of the symbol :Caution! Read the instruction manual before using the

instrument.
In this manual, safety instructions prefixed with this symbol will, if not observed or followed,
bring hazardous conditions for the operator or for the instrument and installation.

You have just acquired an Earth Tester and we thank you for your confidence.
To get the best service from your instrument:

- read carefully this user’s manual,

- respect the safety precautions in it,

- stick the label corresponding to your language on the back of the instrument.

SAFETY IN USE

■ Before connecting the C.A 6421, check for any hazardous voltage in the earth
connection to be tested.

■ Before opening the battery trap-door, check that no test lead is connected to the
insrument.

■ Before performing a resistance measurement, check the galvanometer rating (the
pointer must stop at 0.5 Ω).

WARRANTY

Unless notified to the contrary, our instruments are guaranteed from any manufacturing
defect or material defect. They do not bear the specification known as the safety specification.
Our guarantee, which may not under any circumstances exceed the amount of the invoiced
price, goes no further than the repair of our faulty equipment, carriage paid to our workshops.
It is applicable for normal use of our instruments, and does not apply to damage or
destruction caused, notably by error in mounting, mechanical accident, faulty maintenance,
defective use, overload or excess voltage.
Our responsability being strictly limited to the pure and simple replacement of the faulty parts
of our equipment, the buyer expressly renounces any attempt to find us responsible for
damages or losses caused directly or indirectly.

Our guarantee is applicable for twelve (12) months after the date on which the
equipment is made available. The repair, modification or replacement of a part during the

guarantee period will not result in this guarantee being extended.

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SUMMARY

Page

1. PRESENTATION .......................................................................................................................................................................... 16

2. DESCRIPTION ...................................................................................................................................................................... 17

3. OPERATING MODE ......................................................................................................................................................... 18

3.1. Earth connection resistance measurement ........................................................................... 18

3.2. Resistance measurement ...................................................................................................................... 20

3.3. Fault indications ............................................................................................................................................. 20

4. CHARACTERISTICS ........................................................................................................................................................ 21

5. MAINTENANCE ................................................................................................................................................................... 25

5.1. Routine maintenance ................................................................................................................................. 25

5.2. Calibration ........................................................................................................................................................... 26

5.3. Repair ...................................................................................................................................................................... 26

6. TO ORDER ............................................................................................................................................................................... 27

1. PRESENTATION

This self-powered and watertight tester was designed for measuring earth connection
resistances in outdoor sites. It is particulary adapted to harsh environments and may be used
in all weather conditions.

It is very easy to use thanks to:

■ a single pushbutton for triggering your measurements

■ a large galvanometer, directly graduated in Ω

■ three lights indicating any fault liable to vitiate test results

■ a low-battery indicator built in the galvanometer

■ three color-coded screw-on terminals making test connections easier

■ one captive bar

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2. DESCRIPTION

1 Test input terminal E (green))
2 Test input terminal S (blue)
3 Test input terminal H (red)
4 Captive bar S - H for two-wire resistance measurements

5 Moving-coil galvanometer, logarithmic scale: 0,5....1000 Ω

6 Low-battery indicator
7 Galvanometer calibration screw
8 Fault indicator - current circuit (E - H)

9 Fault indicator - voltage circuit (E - S)
10 Parasitic voltage indicator - voltage circuit (E - S)
11 Pushbutton for triggering measurements

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3. OPERATING MODE

3.1 EARTH CONNECTION RESISTANCE MEASUREMENT

Two rod-based methods let you measure earth connection resistances with the C.A 6421.
The Tagg-method (said “ of the 62% ”) is indiscutably the best. It requires an unhindered stretch
of land at least 100 m in length, close to the earth connection to be tested.
The triangular method also provides suitable results, although test results may be vitiated in
the event of overlapping vicinitiy areas.

3.1.1. Measurements using the method “ of the 62% ”

Switch off the installation and disconnect it from the ground by opening the
earthing rod!

1. Connect terminal E to the earth connection to be tested.

2. Check that the bar 4 was not installed between terminals S and H.

3. Push down the rod H into the earth as deeply as possible, at a distance “a” from the earth
connection (E).
Note: this distance will be proportional to the depth of the earth connection (wider vicinity area).

4. Similarly, push down the rod S by lining it up with the earth connection E and the rod H,
at a distance of about 62% of “a”.

5. Connect the test leads between the rods and their respectives terminals.

6. Press the pusbutton 11 till the galvanometer pin stabilizes. Make sure none of the three
indicators is blinking, otherwise check the connections (see § 3.3: FAULT INDICATION)
and repeat the measurement.

earth bar

E

earth
point

0 % 72 % 100 %

E S H

S'' S'

S

52%62

%

Earth resistance measurement using the method of the 62%

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H

Checking measurement readings

7. Write down the measurement reading.

8. Repeat the measurement after a while.

9. Move the rod S toward H over a distance equal to 10% of “a”. Start the measurement and

write down the reading.

10. Move the rod S from its initial location toward E, over a distance equal to 10% of “a”. Start

the measurement and write down the reading.
The measurement is correct if all three readings have the same order of magnitude.
Otherwise, increase “a” and repeat the above steps.

Do not forget to connect the earth connection again after the test.

3.1.1. Measurement using the “ triangular ” method

Switch off the installation and disconnect it from the ground by opening the
earthing rod!

1. Connect terminal E to the earth connection to be tested.

2. Check that the bar 4 was not installed between terminals S and H.

3. Push down the rods S and H into the earth as deeply as possible, in order that they form

with the earth connection an equilateral triangle E - S - H.

4. Press the pusbutton 11 till the galvanometer
pointer stabilizes. Make sure none of the three
indicators is blinking, otherwise check the
connections (see § 3.3: FAULT INDICATIONS)
and repeat the measurement. Write down the
reading.

5. Move the rod S (without moving H) in order
to form a new triangle E - S’ - H.

6. Start a new measurement and compare the
reading with the previous one. The
measurement will be considered as correct if
there is little difference between the two
readings (only some %). Otherwise, this
indicates that the rod S is located within a
vicinity area. Make the triangle much larger
and repeat the above steps.

Earth resistance measurement using the triangular method

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Do not forget to connect the earth connection again after the test.

3.2 MEASUREMENT OF RESISTANCE

The instrument can also measure resistances under 1 kΩ.

Diconnect the resistance from any voltage source.

1. Short the S and H terminals using the bar 4 .

2. Connect the E and H terminals to the resistance to be measured.

3. Press the pushbutton 11 till you read the measurement Make sure none of the three

indicators is blinking; otherwise check the connection (see § 3.3: FAULT INDICATIONS) and
repeat the measurement.

N.B: With very low earth resistances, you must consider test lead resistance (about 22.5 mΩ
per meter, for the test leads supplied as accessories).

3.3 FAULT INDICATIONS

■ Galvanometer pointer

If the pointer stops on the right side, this indicates that you measured more than 1000 Ω
(overranging condition) or that the circuit is open.
If the pointer stops on the left side, this indicates that you measured less than .5 Ω . This may
also indicate that the H and E rods, or the S and E rods, were inverted.

Check the connections.

■ Indicator 6 on

Battery condition is permanently checked during the measurements. If this is the first time the
battery indicator comes on, you have twenty minutes battery time left.

Change the batteries quickly. See § 5.1.2.

■ FAULT indicator 8 blinking

There is a fault in the current circuit (E - H). It may result from:

- current circuit resistance too high between E and H

- low measurement condition (R < 0,5 Ω)

- open fuse

Check the rods, the leads, the connections and the fuse (see § 5.1.3).

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■ HIGH RESISTANCE indicator 9 blinking

There is a fault in the voltage circuit (E - S). At the start of the measurement, the instrument
automatically checks the resistance between E and S. If the resistance is higher than 50 kΩ,
the indicator 9 blinks, meaning your measurement may be impaired by the voltage circuit
resistance.
N.B: The indicator will blink during the whole measurement, even if the resistance comes
under 50 kΩ.

Check the rods, the leads and their connections.

■ HIGH NOISE indicator 10 blinking

There are parasitic voltages in the voltage circuit (E - S), interfering with the measurement.

Move the rods.

4. CHARACTERISTICS

REFERENCE CONDITION

Temperature 23°C ±3 K

Relative humidity 45% < RH < 55%
Power supply voltage 10.5 V ± 0.2 V

Auxiliary resistances RH, RS et R
Parasitic AC and DC voltages none

Electric field none
Magnetic field < 40 A/m

E

none

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METROLOGY CHARACTERISTICS

Measurement range 0.5...1000 Ω
Short-circuit current 10 mA (square wave 128 Hz)
Accuracy ± 5%L ± 1% of galvanometer scale length
Voltage at no-load condition 24 V

eff

Response time about 4 seconds

INFLUENCE QUANTITIES

Range Max. variation
Temperature -10...+55°C ± 5% per 10°C
Relative humidity 20...90% HR ± 10% ± 0.1 Ω
Operating voltage 8.8...12.5 V minor
Voltage circuit load (1) 50 kΩ ± 1% per 10 kΩ
Current circuit load (2) 3000 times the reading from 1 to 10 Ω : ± 2% per 1 kΩ ± 0.1 Ω

up to 50 kΩ from 10 to 1000 Ω : ± 3% per 10 kΩ
Direct voltage 0...20 V (3) minor
Parasitic ~ voltages on H 7 V
Parasitic ~ voltages on S 3 V

for readings < 1 Ω ± 5%

eff

5 V

for readings ≥ 1 Ω ± 5%

eff

eff

minor

(1) Resistance measured + resistance of rod E + resistance of rod S + lead resistance
(2) Resistance measured + resistance of rod E + resistance of rod H + lead resistance
(3) Possible blinking of HIGH RESISTANCE indicator beyond 5V

ELECTRICAL CARACTERISTICS

Power supply source 8 alkalin R6 1.5V batteries or 8 accumulators

Allowage voltage range 8.8...12.5 V

Average battery time 1680 measurements x 15 secondes (at 23°C 3K, with 8 alkalin

batteries), permanently checked

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DISPLAY

Galvanometer magneto-electric (moving-coil) type, range: 100 µA,

accuracy class: 1.5
logarithmic scale: 77 mm, graduated from 0.5 to 1000 Ω

Low battery condition the indicator 6 built in the galvanometer comes on

Current circuit fault indicator blinking red LED - FAULT (E - H)
Voltage circuit fault indicator

n Resistance oo blinking red LED - HIGH RESISTANCE (E - S)
n Parasitic noise blinking red LED - HIGH NOISE (E - S)

MECHANICAL CHARACTERISTICS

Protection index IP 54 according to IEC 529 and NF EN 60 529

Free fall 25 cm according to EC 68-2-32
Resistance to shocks 50 gn (gn = 9,81 m/s²) according to IEC 68.2.27

Resistance to impacts IK 04 according NF EN 50 102
Resistance to vibrations ± 1 mm, from10 to 55 Hz according to IEC 68.2.6

Dimensions (L x l x h) 238 x 136 x 150 mm
Lead connections through 3 color-coded terminals, for banana plugs ∅ 4 mm or for fork

sockets 6 mm

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ENVIRONMENTAL CONDITIONS

Domaine nominal de référence
Domaine d'utilisation
Domaine de stockage

100

90

80

70

60

50

40

30

20

10

Humidité en % HR

- 40 - 20 0 20 40 60 80

Température

en °C

Humidity in % RH

Standard reference domain
Operating domain
Storage domain

COMPLIANCE TO STANDARDS

Electrical safety (according to IEC 1010-1)

- Double insulation

- Installation class III

- Pollution degree 2

- Service voltage 24 V

eff

Temperature in °C

Electromagnetic compatibility

■ Emissions and immunity in an industrial setting compliant with IEC 61326-1.

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5. MAINTENANCE

Only use the specified spare parts. The manufacturer will not be held as
responsible for any accident resulting from a repair made outside its after-sales
service or accredited repair centers.

5.1. ROUTINE MAINTENANCE

5.1.1. Cleaning

Use a damp cloth or a sponge slightly wetted with soapy water. Do not use alcohol, petrol
or any other hydrocarbon-based product.

5.1.2. Replacing the batteries or accumulators

Battery condition is automatically and permanently checked. When the indicator 6 is on,
battery time is nearly over and the batteries need to be changed rapidly. In order to
avoid any operating failure, take a pack of 8 batteries with the instrument when you are
about to perform field measurements.

Before replacing the batteries, make sure no lead is connected to the instrument.
Replace all batteries at the same time.
Do not mix the batteries and accumulators.

Unscrew the two captive screws located under the instrument and remove the battery trap­door. Replace all 8 batteries by 8 new batteries of the same type, and observe the polarity.
Put back the battery trap-door.

5.1.3. Replacing the fuse

The FAULT indicator blinks if the current circuit fuse is burnt out. This may be checked by
installing, between the S and E terminals, a resistance within the range 1 -1000 Ω , then by
shorting the E and H terminals (with the bar 4 open and the test leads disconnected). If the
FAULT indicator is still blinking, replace the fuse. Remove the battery trap-door, unscrew the
fuse holder, take out the fuse and replace it by a fuse of the same type (0.1 A - 250 V). Put
back the battery trap-door.

5.1.4. Storage

If the instrument has not been used for a long time, remove the batteries from their
compartment. Do not store the instrument in climatic conditions other than those specified
(see § 4: CHARACTERISTICS).

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5.2. CALIBRATION

Like all measuring or testing devices, the instrument must be checked regularly.

This instrument should be checked at least once a year. For checking and calibration, contact
one of our accredited metrology laboratories (information and contact details available on
request), at our Chauvin Arnoux subsidiary or the branch in your country.

5.3 REPAIR

For all repairs before or after expiry of warranty, please return the device to your
distributor.

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6. TO ORDER

ref.

■ C.A 6421 EARTH TESTER .................................................................................................. P01123011

shipped with batteries, transportation belt and instruction manual.

C.A 6421 accessories:

■ Transportation bag ...................................................................................................................... P01298006

C.A 6421 spare parts:

■ Transportation belt ...................................................................................................................... P01298005

■ Fuse HPC 0,1 A - 250 V (pack of 10) ........................................................................... P01297012

■ 1,5 V alkalin LR6 batteries (pack of 12) ........................................................................ P01296033A

Measurement accessories:

■ TERRE PRESTIGE kit .............................................................................................................. P01102022

semi-rigid pouch including:

- two T-rods

- 100 m red cord on a roller

- 100 m blue cord on a roller

- 10 m green cord on a roller

- one mallet of 1 kg

- 5 spade-lug / 4 mm banana adapters

TERRE PRESTIGE kit spare parts:

■ Semi-rigid pouch ........................................................................................................................ P01298026

■ one smooth T-rod ...................................................................................................................... P01102031

■ 100 m red cord on a roller ..................................................................................................... P01295261

■ 100 m blue cord on a roller ..................................................................................................... P01295264

■ 10 m green cord on a roller .................................................................................................. P01102026

■ TERRE STANDARD Kit ............................................................................................................ P01102021

soft pouch including:

- two straight rods,

- two wrenches to extract the rods from the earth,

- 50 m red cord on a roller

- 50 m red cord on a roller,

- 10 m green cord,

- one mallet of 1 kg

- 5 spade-lug / 4 mm banana adapters

TERRE STANDARD kit spare parts

■ 50 m blue cord on a roller ....................................................................................................... P01295265

■ 50 m red cord on a roller.......................................................................................................... P01295262

■ 10 m green cord ............................................................................................................................. P01102026

■ One straight rod ........................................................................................................................... P01102031

■ Flexible pouch n°1 ...................................................................................................................... P01298066

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01 - 2013

Code 906129363 - Ed. 2

DEUTSCHLAND - Chauvin Arnoux GmbH

Straßburger Str. 34 - 77694 Kehl / Rhein
Tel: [phone] - Fax: [phone]

ESPAÑA - Chauvin Arnoux Ibérica SA

C/ Roger de Flor N° 293, Planta 1
08025 Barcelona
Tel: [phone] - Fax: [phone]

ITALIA - Amra SpA

Via Sant’Ambrogio, 23/25 - 20050 Bareggia di Macherio (MI)
Tel: [phone] - Fax: [phone]

ÖSTERREICH - Chauvin Arnoux Ges.m.b.H

Slamastrasse 29/2/4- 1230 Wien
Tel: [phone] - Fax: [phone]

SCANDINAVIA - CA Mätsystem AB

Box 4501 - SE 18304 TÄBY
Tel: [phone] - Fax: [phone]

SCHWEIZ - Chauvin Arnoux AG

Einsiedlerstraße 535 - 8810 Horgen
Tel: [phone] - Fax: [phone]

UNITED KINGDOM - Chauvin Arnoux Ltd

Unit1 Nelson Court - Flagship Square- Shaw Cross Business Park
DEWSBURY - West Yorkshire - WF12 7TH
Tel: [phone] - Fax: [phone]

MIDDLE EAST - Chauvin Arnoux Middle East

P.O. BOX 60-154 - 1241 2020 JAL EL DIB (Beirut) - LEBANON
Tel: [phone] - Fax: [phone]

CHINA - Shanghai Pu-Jiang - Enerdis Instruments Co. Ltd

3 F, 3 rd Building - N° 381 Xiang De Road - 200081 SHANGHAI
Tel: [phone] - Fax: [phone]

USA - Chauvin Arnoux Inc - d.b.a AEMC Instruments

200 Foxborough Blvd. - Foxborough - MA 02035
Tel: [phone] - Fax: [phone]

http://www.chauvin-arnoux.com

190, rue Championnet - 75876 PARIS Cedex 18 - FRANCE

Tél. : [phone] - Fax : [phone] - [e-mail]

Export : Tél. : [phone] - Fax : [phone] - [e-mail]

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