Amprobe GP-2A Operating Manual

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GP-2 GeoTest

Instruction Manual

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GP-2 GeoTest

1. PRECAUTIONS AND SAFETY MEASURES.....................................................................3

1.1. PRELIMINARY INSTRUCTIONS ........................................................................................3

1.2. DURING USE......................................................................................................................4

1.3. AFTER USE.........................................................................................................................4

2. GENERAL DESCRIPTION.....................................................................................................5

2.1. INSTRUMENT DESCRIPTION...........................................................................................6

3. PREPARING THE INSTRUMENT........................................................................................8

3.1. INITIAL CHECK...................................................................................................................8

3.2. POWER SUPPLY................................................................................................................8

3.3. CALIBRATION.....................................................................................................................8

3.4. STORAGE...........................................................................................................................8

4. SWITCH FUNCTIONS............................................................................................................9

4.1. EARTH 2 WIRES.................................................................................................................9

4.2. EARTH 3 WIRES...............................................................................................................12

4.3. "ρ" MODE (Resistivity of the Earth)...................................................................................15

4.3.1. SELECTING THE UNITS OF MEASURE.........................................................................15

4.3.2. OPERATING INSTRUCTIONS....................................................................................15

4.4. ANOMALOUS SITUATIONS WHICH CAN OCCUR DURING TESTS............................19

5. HOW TO SAVE, RECALL AND CANCEL DATA.............................................................22

5.1. TO SAVE: "SAVE" KEY.....................................................................................................22

5.2. TO RECALL: "RCL" KEY...................................................................................................23

5.3. TO CANCEL: "CLR" KEY..................................................................................................24

6. RESET AND DEFAULT PARAMETERS...........................................................................26

6.1. HARD RESET...................................................................................................................26

6.2. DEFAULT PARAMETERS................................................................................................26

6.2.1. DEFAULT PARAMETERS..........................................................................................26

7. CONNECTING THE INSTRUMENT TO A PC..................................................................27

8. MAINTENANCE.....................................................................................................................28

8.1. GENERAL..........................................................................................................................28

8.2. BATTERY REPLACEMENT..............................................................................................28

8.3. CLEANING.........................................................................................................................28

9. TECHNICAL SPECIFICATIONS.........................................................................................29

9.1. TECHNICAL FEATURES..................................................................................................29

GENERAL FEATURES................................................................................................................31

9.2. OPERATING CONDITIONS..............................................................................................32

9.2.1. ENVIRONMENTAL CONDITIONS ................................................................................32

9.2.2. EMC..................................................................................................................32

9.3. ACCESSORIES.................................................................................................................32

9.3.1. STANDARD AND OPTIONAL ACCESSORIES..................................................................32

10. SERVICE.................................................................................................................................33

10.1. WARRANTY......................................................................................................................33

10.2. SERVICE...........................................................................................................................33

11. PRACTICAL REPORTS FOR ELECTRICAL TESTS......................................................35

11.1. EARTH RESISTANCE MEASUREMENT .........................................................................35

11.2. EARTH RESISTIVITY MEASUREMENT ..........................................................................38

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GP-2 GeoTest

Warning: Should you fail to keep to the prescribed instructions you could

1. PRECAUTIONS AND SAFETY MEASURES

This instrument complies with European Community (EC) standards: EN61557-1, EN61557-5 and EN 61010-1.

WARNING: For your safety as well as that of the instrument you are

recommended to follow the procedures described in this instruction manual and carefully read all the notes preceded by

the symbol .

Before and during measurements please carefully heed the instructions below:

F Do not measure in wet or dusty places; F Do not measure in the presence of gas, explosive materials or combustibles; F Do not touch the circuit under test if no measurement is being taken; F Do not touch exposed metal parts, unused terminals, circuits, etc… F Do not use the instrument if it seems to be malfunctioning (i.e. if you notice

deformations, breaks, leakage of substances, absence of messages on the display etc…);

F Be particularly careful when measuring voltages higher than 25V in potentially

hazardous areas (such as building sites, swimming pools and so on) and higher than 50V in any area, in order to avoid the risk of electrical shocks.

The following symbols are used in this manual:

damage the instrument and/or its components or endanger your personal safety.

Switch

1.1. PRELIMINARY INSTRUCTIONS

F This instrument has been designed for use in environments with pollution rating 2.

It can be used for tests on installations of excess voltage category III max 250V (phase to earth).

F Always keep to the usual safety standards intended to:

- protect you against dangerous currents;

- protect the instrument against incorrect operation.

F Only the accessories supplied with the instrument guarantee compliance with the

safety standards. Accordingly, they must be used only when in good condition and, if necessary, they must be replaced with identical factory parts.

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GP-2 GeoTest

F Use the instrument in TT, TN, IT system and industrial, civil, medical electrical plants,

in normal conditions (contact voltage limit 25V) and in particular condition (contact voltage limit 50V).

F Do not take measurements on circuits exceeding the specified current and voltage

limits.

F Do not take measurements under conditions exceeding the limits stated in paragraphs

9.2.1 and 9.2.2.

F Make sure that the batteries are properly installed. F BEFORE connecting the alligator clips to the circuit under test, make sure that the

switch is in the correct position.

F Make sure that the display shows the same function as that to which the switch is set.

1.2. DURING USE

Please read carefully:

WARNING: Should you fail to keep to the prescribed instructions you could

damage the instrument and/or its components or endanger your personal safety.

F Before setting, or changing, the switch position, disconnect the alligator clips from the

circuit under test.

F When the instrument is connected to the circuit under test, do not touch any unused

terminal(s).

F Do not take resistance measurements in the presence of external voltages; even if the

instrument is protected, any excessive voltage may cause unit malfunction.

WARNING: If, during use, the symbol appears, suspend the test and

replace the batteries (see paragraph 8.2). The instrument is able to keep in memory any previously saved data for approximately 10 minutes.

1.3. AFTER USE

F After use, move the switch to the OFF position. F If you do not expect to use the instrument for more than 30 days, remove the batteries.

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GP-2 GeoTest

2. GENERAL DESCRIPTION

Thank you for purchasing a quality AMPROBE Test Instrument. This instrument will provide you with accurate and reliable measurements provided that it is used according to this manual’s instructions

The GP-2 GeoTest is able to measure:

F EARTH 2 WIRES: 2 wires earth resistance F EARTH 3 WIRES: 3 wires earth resistance

F ρρ: 4 wires earth resistivity

The GP-2 GeoTest uses the "Fall of potential" method of measurement for all of the above tests.

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2.1. INSTRUMENT DESCRIPTION

ESC

DISP

SAVE

CLR

Rotary switch:

GP-2 GeoTest

DIST

AVG

Permits selection of the desired function

OFF

RCL

Figure 1: Front panel

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GP-2 GeoTest

AVG

ESC

SAVE

DIST

RCL

DISP

CLR

F Displays the average value of the earth resistivity, calculated on the

basis of all valid measurements taken.

F Selects the distance "D" between the earth rods (ρ resistivity test).

F Increases the value of the parameter D; Scrolls through the recorded

test results; or Selects the unit m/ft.

F Decreases the value of the parameter D; Scrolls through the recorded

test results; or Selects the unit m/ft.

F Starts a measurement.

F Escape from (exit) the selected function or mode.

F Saves test results.

F Recall recorded test results.

F Displays recorded data from the selected memory location.

F Deletes:

- the average value of the measurements and the number of the tests included in the average value calculations

- recorded test results from a specified memory location

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GP-2 GeoTest

3. PREPARING THE INSTRUMENT

3.1. INITIAL CHECK

This instrument has been carefully checked for proper electrical and mechanical function prior to shipment. All possible precautions have been taken in order to deliver it in the best possible condition.

Nevertheless, on receipt of the instrument we suggest that it be checked completely to make sure that no damage has occurred in transit. Should you find anomalies please contact the carrier immediately.

Please also make sure that the package contains all the accessories and parts listed in paragraph 9.3.1. In case of discrepancies please contact your dealer.

Should it be necessary to return the instrument, please refer to the instructions in paragraph 10.

3.2. POWER SUPPLY

The instrument is powered by 6 size 'AA' 1.5V batteries ( LR6– AM3 – MN 1500) not included in the package.

For correct installation of the batteries see paragraph 8.2. When the batteries are low the symbol appears. For replacement see paragraph 8.2.

3.3. CALIBRATION

The instrument complies with the standards mentioned in this manual. Its performance is guaranteed for one year from the date of purchase.

3.4. STORAGE

To guarantee accurate measurements, after extended storage in severe environmental conditions please allow the unit to normalize to proper ambient conditions.(see environmental conditions listed at paragraph 9.2.1).

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GP-2 GeoTest

Secondary display on the

4. SWITCH FUNCTIONS

4.1. EARTH 2 WIRES

Whenever it is not possible to drive rods into the ground to take a 3-wire measurement, or in case of TT installations it is possible to use the simplified 2-wire method (Figure 2) which gives an excess (therefore safer) value. To carry out the test a suitable auxiliary rod is necessary; a rod is “suitable” when its earth resistance is negligible and it is independent of the earth equipment under test. In Figure 2 a water pipe has been used as auxiliary rod. However, any metal body driven into the ground can be used, provided that the above said requirements are met. Although this test is not provided for by the CEI 64.8 standard at present, it gives a value, which many 3-wire comparison tests have proved to be revealing for earth resistance.

ESE S

Figure 2: 2 wire earth resistance measurement

Measuring procedure:

F Insert the 4 connectors (black, red, blue and green) of the measuring cables into the

corresponding input terminals of the instrument (E, S, H, ES).

F Connect the alligator clips as shown in Figure 2. F Position the switch on EARTH 2 WIRES.

Display appearance:

Main display

Secondary display on the lefthand side:

In this stage it displays the eventual interfering voltage present on the circuit

------

right-hand side

0 0 V - - -- - -

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GP-2 GeoTest

Average value of the resistance calculated Value of the

resistance

Press GO to take the measurement and read the result on the display. At the end of the test, a screen similar to the following will be displayed.

NOTE! If you keep pressing GO, the instrument takes more measurements

consecutively. When a new value is acquired, the symbol Ω blinks on the main display, the instrument emits a short sound and the counter shown on the

secondary display on the left-hand side is updated. This counter indicates the number of measurements calculated on the basis of the average resistance value.

No. of earth resistance measurements

included in the calculation of the average resistance

0.960.96 ΩΩ

2 2 0.93 0.93 ΩΩ

as:

(Val1+Val2+…+Valn)/(No. measurements)

WARNING: When the message “Measuring” appears on the display, the

instrument is measuring. Do not disconnect the alligator

clips during the measurement.

Ex.: if the operator takes three measurements consecutively, the instrument will

display:

- 1st measurement: main display = measured resistance value (Ex: 0.90Ω)

secondary display on the left-hand side = 001 (no. of measurements = 1 means that 1 earth measurement has been taken) secondary display on the right-hand side = average of the measurements taken (in case just one measurement has been taken the average value is equal to the measured value, in this case 0.90Ω)

- 2nd measurement: main display = measured resistance value (Ex: 0.96Ω)

secondary display on the left-hand side = 002 (no. of measurements = 2 means that 2 earth measurements have been taken consecutively) secondary display on the right-hand side = average of the measurements taken ((Val1+Val2)/no. of measurements = (0.90+0.96)/2 = 0.93Ω)

- 3rd measurement: main display = measured resistance value (Ex: 0.93Ω)

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GP-2 GeoTest

SAVE

CLR

secondary display on the left-hand side = 003 (no. of measurements = 3 means that 3 earth measurements have been taken consecutively) secondary display on the right-hand side = average of the measurements taken ((Val1+Val2)/no. of measurements = (0.90+0.96+0.93)/3 = 0.93Ω)

NOTE! A test with a result over 700Ω is not inserted in the calculation of average value.

Example:

1st measurement Main display: 1,07Ω

Secondary display on the left-hand side: 1 Secondary display on the right-hand side: 1,07Ω

2nd measurement Main display: 4,15Ω

Secondary display on the left-hand side: 2 Secondary display on the right-hand side: 2,61Ω

3rd measurement (not inserted in the average value)

Main display: 1018Ω Secondary display on the left-hand side: 2

Secondary display on the right-hand side: 2,61Ω

Press CLR if you want to cancel the average value of the resistance and the no. of measurements which are included in the calculation (displayed on the secondary displays on the right-hand side and on the left-hand side respectively). A screen similar to the following will be displayed:

Last value of resistance measured

0.960.96 ΩΩ

- - - - - - - - -- - -

The test results can be stored in memory by pressing SAVE (see paragraph

5.1).

NOTE! The resistance measurement is taken according to a 4-wire voltmetric method.

Therefore, it is not affected by the resistance value of the cables used: it is not necessary to calibrate the cables or their extension.

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GP-2 GeoTest

Secondary display on the left-

Secondary display on the

4.2. EARTH 3 WIRES

The measurement is taken according to what is prescribed for CEI 64.8, IEC 781, VDE 0413, EN61557-5 standards.

Small earth plant:

- current probe (terminal H, blue wire) positioned a distance from the earth equipment outline

CAT III 440 V P-N-PE 250 V

ESES

corresponding to five times the diagonal of the area of the earth equipment.

Large earth plant:

- current probe (terminal H, blue wire) positioned a distance from the earth equipment outline corresponding the diagonal of the area of the earth equipment.

Figure 3: 3 wires earth resistance measurement

Measuring procedure:

F Insert the 4 connectors (black, red, blue and green) of the cables into the

corresponding input terminals of the instrument (E, S, H, ES).

F Connect the alligator clips as shown in Figure 3. F Position the switch to EARTH 3 WIRES.

Display appearance:

Main display

hand side:

In this mode it displays the eventual interfering voltage present on the circuit

------

right-hand side

0 0 V - - -- - -

Press GO to take the measurement and read the value on the display. At the end of the test, a screen similar to the one below will be displayed.

NOTE! If you keep pressing GO, the instrument takes more measurements

consecutively. When a new value is displayed, the symbol Ω blinks on the main display, the instrument emits a short sound and the counter shown on the

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secondary display on the left-hand side is updated. This counter indicates the

No. of earth resistance

Average value of the resistance calculated Value of the resistance

quantity of measurements included in the calculation of the average resistance value.

measurements included in the calculation of the average resistance

WARNING: When the message “Measuring” appears on the display, the

instrument is measuring. Do not disconnect the alligator

clips during the measurement.

GP-2 GeoTest

measured

0.960.96 ΩΩ

2 2 0.93 0.93 ΩΩ

as:

(Val1+Val2+…+Valn)/(no. measurements)

Ex.: if the operator takes three measurements consecutively, the instrument will

display:

- 1st measurement: main display = measured resistance value (Ex: 0.90Ω)

- 2nd measurement: main display = measured resistance value (Ex: 0.96Ω)

- 3rd measurement: main display = measured resistance value (Ex: 0.93Ω)

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GP-2 GeoTest

SAVE

CLR

Last resistance value

NOTE! A test with a result over 700Ω is not inserted in the calculation of average value.

Example:

1st measurement Main display: 1,07Ω

Secondary display on the left-hand side: 1 Secondary display on the right-hand side: 1,07Ω

2nd measurement Main display: 4,15Ω

Secondary display on the left-hand side: 2 Secondary display on the right-hand side: 2,61Ω

3rd measurement (not inserted in the average value)

Main display: 1018Ω Secondary display on the left-hand side: 2

Secondary display on the right-hand side: 2,61Ω

Press CLR if you want to cancel the average resistance value and the no. of measurements, which are included in the calculation (displayed on the

secondary displays on the right-hand side and on the left-hand side respectively). A screen similar to the following will be displayed:

measured

0.960.96 ΩΩ

- - - - - - - - -- - -

NOTE! The resistance measurement is taken according to a 4-wire voltmetric method.

Therefore, it is not affected by the resistance value of the cable used: it is not necessary to calibrate the cables or their extension.

The test results can be stored in memory by pressing SAVE (see paragraph

5.1)

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GP-2 GeoTest

4.3. "ρρ" MODE (Resistivity of the Earth)

The measurement is taken according to CEI 64.8, IEC 781, VDE 0413, EN61557-5 standards.

4.3.1. Selecting the units of measure

WARNING Whenever the units of measure are changed the instrument will perform a hard reset and all the data in the

memory will be erased (see paragraph 6.1).

SELECT THE UNIT press and hold the "RCL" key and turn the rotary switch. The

instrument will display a screen that permits selection of the correct measurement unit: m or ft (used to determine distance between the ground rods) with the s or t keys. Press the SAVE or ESC key to save the measurement unit selected.

NOTE! Regardless on the unit of distance D set up (either ft or m) the resistivity will

be automatically calculated in OhmMeters!

4.3.2. Operating Instructions

Measuring procedure:

F Drive the 4 earth rods into the ground at the same distance D. The distance D

between the rods is usually 3 to 30 ft (1 to 10 m). The distance D between the rods determines the depth at which the earth resistivity is measured. In order to identify the distance (and therefore depth) corresponding to the lowest resistivity value, the test must be repeated several times, positioning the rods at different distances. This depth will then have to be physically reached by the rods of the earth equipment.

F Insert the 4 connectors (black, red, blue and green) of the cables into the

corresponding input terminals of the instrument (E, S, H, ES).

F Connect the alligator clips as shown in Figure 4.

CAT III 440 V P-N-PE 250 V

Figure 4: 4 wire earth resistivity measurement

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F Position the switch on ρρ.

Value of the parameter D

Measured earth resistivity value

DIST

ESC

Display appearance:

To select the distance D between the rods. This parameter can be chosen from the following values (expressed in ft/m):

3, 6, 9, 12, 15, 18, 21, 24, 27, 30

GP-2 GeoTest

--- --- ρρ

0 0 V 010010 ft/m

1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Press s or t to select the value of the parameter D:

006 006 ft/m ρρ

Press ESC to confirm the value previously set.

Press GO to take the measurement and read the value on the display. At the end of the test a screen similar to the one following will be displayed.

36.536.5 ρρ

Measurement unit: Ωm

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GP-2 GeoTest

ESC

AVG

NOTE! Regardless on the unit of distance D, which is set up (either ft or m) the

resistivity will be automatically calculated in OhmMeters!

WARNING: When the message “Measuring” appears on the display, the

instrument is measuring. Do not disconnect the alligator

clips during the measurement.

NOTE! If you keep pressing GO, the instrument takes more measurements

consecutively. When a new value is acquired, the symbol Ωm blinks on the main display, the instrument emits a short sound and, if the measured value is

inserted in the calculation of the average resistivity value, the message “Add” appears on the secondary display on the right-hand side.

The earth resistivity value is an indispensable parameter to calculate the resistance value of the rods, which will be used for the earth equipment (see paragraph 11.2).

Use AVG to display the average resistivity value measured. This key is enabled only when the message “Add” appears on the secondary display on the lefthand side.

NOTE! The value of the resistivity corresponding to a resistance value over 700Ω is not

inserted in the calculation of average value.

Example:

1st measurement Main display: 6.6 Ωm

Secondary display on the right-hand side: empty 2nd measurement Main display: 26 Ωm

Secondary display on the right-hand side: Add Press AVG: main display: 16.4 Ωm

secondary display on the left-hand side: 2 secondary display on the right-hand side: Add

3rd measurement (not inserted in the average value)

Main display: 6.3 kΩm Secondary display on the right-hand side: Add

Press AVG: main display: 16.4Ωm

secondary display on the left-hand side: 2 secondary display on the right-hand side: Add

Use ESC to leave the screen showing the average value and return back to the screen corresponding to the last measurement taken.

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GP-2 GeoTest

SAVE

This screen appears

Press SAVE to store the test results in memory (see paragraph 5.1).

Example: You position the rods at a distance D of 3 feet and take 3 resistivity measurements:

7.7 7.7 ΩΩm ρρ 7.1 7.1 ΩΩm ρρ

AAdd

1st meas. 2nd meas. 3rd meas.

a) 1st measurement: you see the measured value but not the message “Add”. b) 2nd measurement: you see the message “Add”. This means that the second

measurement is included in the calculation of the average; by pressing AVG you will get also the average value calculated.

7.4 7.4 ΩΩm ρρ

002 A 002 Add

The "002" indicates that 7.4Ωm is the average value calculated as the average between the two values previously measured.

Press ESC to return back to the screen corresponding to the second measurement. Upon returning back to the second measurement, press CLR if you want to cancel the average value calculated and the corresponding counter.

7.1 7.1 ΩΩm ρρ

AAdd

after press in AVG

c) 3rd measurement: as with point b) above, but the average value is calculated as

average between the three values measured.

The "003" indicates that 7.3Ωm is the average value calculated as average between the three values previously measured.

7.3 7.3 ΩΩm ρρ

003 A 003 Add

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after pressing AVG

GP-2 GeoTest

SAVE

rP indicates an high resistance value.

4.4. ANOMALOUS SITUATIONS WHICH CAN OCCUR DURING TESTS

WARNING

If the voltmetric circuit (red and green cables) is interrupted, when pressing GO the instrument will not read the minimum voltage, therefore a screen similar to the one beside appears. Make sure that the terminals are connected correctly and that the voltmetric rod (red conductor) has not been driven into a gravelly or scarcely conductive ground. If necessary, pour water around the rod.

νν - - -- - -

PP - - - - - -

THIS RESULT CANNOT BE SAVED.

If the amperometric circuit is interrupted, when pressing GO the

instrument will not read the minimum current, therefore a screen similar to the one beside appears. Make sure that the terminals are connected correctly and that the amperometric rod (blue conductor) has not been driven into a gravelly or scarcely conductive ground. If necessary, pour water around the rod.

rC indicates an high resistance value.

THIS RESULT CANNOT BE SAVED.

WARNING

νν - - -- - -

- - - cc

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GP-2 GeoTest

SAVE

In case both the amperometric circuit and the voltmetric circuit are interrupted, when pressing GO

the instrument will not read the minimum current nor the minimum voltage, therefore a screen similar to the one beside appears. Make sure that the terminals are connected correctly and that the amperometric and voltmetric rods (blue and red conductors) have not been driven into a gravely or scarcely conductive ground. If necessary, pour water around the rod.

THIS RESULT CANNOT BE SAVED.

If the resistance measurement is higher than the full scale of the

instrument, when pressing GO the instrument performs the test and a

screen similar to the one beside appears.

1999ΩΩ is the full scale of the instrument.

WARNING

νν - - -- - -

PP cc

rC and rP indicate an high resistance value both for the voltmetric circuit and for the amperometric circuit.

WARNING

νν>>1999 1999 ΩΩ

- - - - -- - - - -

If the resistivity measurement is higher than the quantity

1999x6.28x(distance between the rods selected) when pressing GO

the instrument performs the test and a screen similar to the one beside appears.

1999ΩΩ is the full scale of the instrument.

WARNING

νν>>1999 1999 ΩΩ

- - - - - -- - - - - -

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If the instrument measures an

SAVE

UC indicates the presence of too high

SAVE

interfering voltage higher than 30V on the amperometric circuit, it does

not perform the test and a screen similar to the one beside appears.

voltage on the amperometric circuit.

THIS RESULT CANNOT BE SAVED.

If the instrument measures an interfering voltage higher than 5V on the voltmetric circuit, it does not

perform the test and a screen similar to the one beside appears.

GP-2 GeoTest

WARNING

νν - - -- - -

UC UC - - -

WARNING

νν - - -- - -

230230v - --

Interfering voltage measured.

THIS RESULT CANNOT BE SAVED.

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5. HOW TO SAVE, RECALL AND CANCEL DATA

SAVE

No. of memory location where the measure

5.1. TO SAVE: "SAVE" KEY

If you want to save the test results:

Press SAVE once.

GP-2 GeoTest

A screen similar to the one beside is

displayed for 3 seconds, the instrument emits a sound, then the screen corresponding to the last measurement taken is displayed.

has been saved.

MEM

003003

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5.2. TO RECALL: "RCL" KEY

RCL

No. of last memory location occupied.

DISP

ESC

Message “rEc ord”:

DISP

If you want to review the test results:

1. Press RCL.

GP-2 GeoTest

If the memory contains

measurements, a screen similar to the one beside will be displayed.

If the memory is empty, a screen

similar to the one beside will be displayed.

the memory contains no values, therefore it is impossible to recall them.

MEM

003003

MEM

EC C

2. Press tt, ss to select the number of the memory location you wish to

3. Press DISP to display the test result associated to the selected

4. Press tt, ss to run over the saved results.

5. Press DISP again to review the memory locations again.

6. Press ESC at any time to leave the memory and return to the selected

consult.

memory location.

measuring function.

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GP-2 GeoTest

RCL

No. of the last memory location occupied.

DISP

CLR

ESC

No. of the last memory location occupied. If you press CLR

5.3. TO CANCEL: "CLR" KEY

If you want to delete the test results:

1. Press RCL. A screen similar to the following will be displayed:

MEM

2. Press tt, ss to select the number of the memory location.

NOTE! when you cancel data the instrument cancels all the saved

data from the SELECTED location up to the last memory location occupied.

3. Press DISP to display the test result associated with the selected memory location. Press DSP again to review the memory locations.

4. Press CLR. The secondary displays are blinking.

MEM

No. of last memory location which will be cancelled.

twice the instrument will cancel the memory locations from no. 2 to no. 8.

At this point you have two possibilities:

0202

08 08 C C ii

Press CLR again to cancel the test results from the selected location (main display) through the last location saved (secondary display on the left-hand side)

Press ESC once to abort the cancellation and return to the number of the memory location.

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Press ESC again to return to the selected measuring function.

ESC

Ex.: 97 test results have been saved.

You want to clear from the 43rd to the 97

- Press RCL.

- Select the 43rd memory location using t and s.

- Press CLR. The symbol “ C C i i ” will blink on the secondary display on the

right-hand. The number 43 will appear on the main display and the number 97 will appear on the secondary display on the left-hand side.

- Press CLR to erase saved data from the 43rd to the 97th location.

location.

GP-2 GeoTest

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GP-2 GeoTest

6. RESET AND DEFAULT PARAMETERS

This paragraph describes the HARD RESET procedure and the default parameters set when a HARD RESET procedure is performed.

6.1. HARD RESET

NOTE! BEFORE RESETTING, TRANSFER ALL SAVED DATA TO A PC.

1. Depress and hold the CLR key while turning on the instrument by rotating the switch.

This screen is displayed for 5 seconds.

The reset has been performed.

The screen corresponding to the selected function is displayed.

H E SE

NOTE! As a consequence of the HARD RESET procedure all the saved is deleted

and the parameter DST (distance between the rods, resistivity measurement) returns to the default value.

6.2. DEFAULT PARAMETERS

The default parameters automatically set when a HARD RESET procedure is performed are the following:

6.2.1. Default parameters

Parameter Default parameter set with the RESET procedure

Parameter DST = distance between the rods, resistivity measurement Test results contained in the memory

DST = 1

Memory empty

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GP-2 GeoTest

7. CONNECTING THE INSTRUMENT TO A PC

Connect the instrument to a PC through the RS-232 port with the supplied cable. Refer to software manual for information how to set up software for download.

In order to transfer recorded data to a PC follow this procedure:

Position the switch on RS232.

Proceed as indicated in the manual of the management software.

SeSe

NOTE! the transmission speed of the GP-2 is 9600 baud (see software manual).

NOTE! On RS232, the instrument will switch off automatically 2 minutes after the last

selecting command from a PC. .

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GP-2 GeoTest

8. MAINTENANCE

8.1. GENERAL

GP-2 GeoTest is a precision instrument. During its use and for its storage follow the recommendations and instructions contained in this manual in order to avoid possible damage or danger. Never use the instrument in environments with a high humidity or temperature. Do not expose the instrument to direct sunlight. Always turn off the instrument after use. If you expect to not use it for extended periods, remove the batteries.

8.2. BATTERY REPLACEMENT

When the symbol appears, the batteries must be replaced.

WARNING: Only qualified technicians can perform this operation.

Before replacing the fuse/fuses disconnect the alligator clips from circuit under voltage in order to avoid electrical shocks.

The tester is capable of keeping the values stored for approx. 10 minutes.

1. Disconnect the cables from the input terminals.

2. Set the switch to the OFF position.

3. Remove the battery cover screws and then remove the cover.

4. Replace the batteries with 6 new ones of the same type: 1.5V– AA (– LR6– AM3 – MN

1500).

5. Reposition the cover and replace the screws.

8.3. CLEANING

Use a soft dry cloth to clean the instrument. Do not use wet clothes, solvents, water etc.

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9. TECHNICAL SPECIFICATIONS

9.1. TECHNICAL FEATURES

Resistance measurement

GP-2 GeoTest

Range (**)

(ΩΩ)

Resolution

(ΩΩ)

Accuracy (*)

0.01 ÷ 19.99 0.01

20.0 ÷ 199.9 0.1 200 ÷ 1999

(*) If RP > 100RE and/or RC > 100RE , RP > 50kΩ and/or RC > 50kΩ, if the instrument carries out the test the accuracy of the instrument is ±(10%Reading)

RP = resistance of the voltage circuit RC = resistance of the current circuit RE = earth resistance

(**) Automatic selection of the range.

Measuring frequency 125Hz / 75Hz/ 41.66Hz Measuring current 10mA Open-terminal measuring voltage 25Vrms Waveform of measuring voltage: sine wave Interfering voltage:

- amperometric circuit: the measurement is taken with the stated accuracy if the interfering voltage is ≤ 3V, while for interfering voltages between 3 and 30V inclusive, the accuracy decreases progressively; with an interfering voltage of about 30V the instrument does not perform the test.

- voltmetric circuit: the measurement is taken if the interfering voltage is ≤ 3V; in case of higher voltages the instrument does not perform the test.

±(2% reading + 3 digits)

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GP-2 GeoTest

Resistivity measurement ρρ

Range (**) Resolution Accuracy (*)

0.6-125.6 Ωm 0.1 Ωm

0.125 – 1.256 kΩm 0.001 kΩm

1.25-19.99 kΩm 0.01 kΩm

20.0 – 199.9 kΩm 0.1 kΩm

(*) If RP > 100RE and/or RC > 100RE , RP > 50kΩ and/or RC > 50kΩ, if the instrument carries out the test the accuracy of the instrument is ±(10%Reading)

RP = resistance of the voltage circuit RC = resistance of the current circuit RE = earth resistance ρ = 2πDRE = calculated resistivity

(**) Automatic selection of the range

Measuring frequency 125Hz / 75Hz/ 41.66Hz Measuring current 10mA Open-terminal measuring voltage 25Vrms Waveform of measuring voltage: sine wave Interfering voltage:

- voltmetric circuit: the measurement is taken if the interfering voltage is ≤ 3V; in case of higher voltages the instrument does not perform the test.

±(2% reading + 3 digits)

Interfering voltage measurement

Range

(V)

500 1

Safety standards

This instrument complies with EN 61010, EN 61557-1, EN 61557-5 standards. Insulation class 2, double insulation

Pollution 2 Maximum altitude 2000m Surge voltage category CAT III 250V (phase to earth)

Resolution

(V)

Accuracy

±(2% reading + 2 digits)

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GP-2 GeoTest

General features

Mechanical features

Dimensions: 222 (L) x 162 (W) x 57 (H) mm Weight (batteries included): about 1000g

Power supply

Batteries: 6 batteries 1.5 V size AA ( LR6 –– AM3 – MN

1500)

Low battery indication: The symbol appears on the display when the

battery voltage is low. Battery life: about 300 measurements Fusible Link: F 100 mA (not accessible to the operator)

Auto Power Off: the instrument will automatically switch off 2

minutes after last selecting a function or PC

command.

Display Features: standard LCD 65mm x 65mm. Memory: 999 memory locations Interfaces: opto-insulated serial output RS232 to transfer data

to a PC.

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GP-2 GeoTest

9.2. OPERATING CONDITIONS

9.2.1. Environmental conditions

Reference temperature: 73 ± 41 F (23° ± 5°C) Operating temperature: 14 ± 122 F (-10°C ÷ 50 °C) Relative humidity: <80% Storage temperature: -4 ± 140 F (-20 ÷ 60 °C) Storage humidity: <70%

9.2.2. EMC

This instrument has been designed in compliance with the EMS standards in force and its compatibility has been tested for:

Irradiated emissions: EN55011 Immunity: EN50140, EN 61000 Electrostatic discharges: EN61000-4-2

R.F. range: EN50140 Fast transient: EN61000-4-4

9.3. ACCESSORIES

9.3.1. Standard and optional accessories

Standard accessories * Code

- 1 carrying case containing:

- 4 earth rods

- 4 cables banana-crocodile Carrying case GP-2CC Optical serial cable C2000 Software and manual www.amprobe.com

GP-2CON

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GP-2 GeoTest

10. SERVICE

10.1. WARRANTY

This instrument is guaranteed against any defects in material and manufacturing for one year, in compliance with the general sale terms and conditions. During the warranty period all defective parts may be replaced, but the manufacturer reserves the right to repair or replace the product.

If the instrument is to be returned, its transport expenses must at the customer's expense. Shipping instructions may be obtained by contacting the factory. A Return Material Authorization (RMA) number must be obtained from the factory prior to return. A report should accompany the returned product, stating the reason(s) for return. The unit should be packed in its original carton or equivalent; any damage that may be due to non-original packing shall be charged to the customer. The manufacturer disclaims any responsibility for damages caused to people and/or objects.

The Warranty is not applicable in the following cases:

• Any repair and/or replacement of accessories and the battery (not covered by the

guarantee).

• Any repair that might be necessary as a consequence of a misuse of the instrument or

of its use with non-compatible devices.

• Any repair that might be necessary as a consequence of improper packaging.

• Any repair that might be necessary as a consequence of attempted service carried out

by unauthorized personnel.

• Any change to the instrument carried out without the express authorization of the

manufacturer.

• Use not intended for as per the instrument specifications or in the instruction manual. The content of this manual cannot be reproduced in any form whatsoever without express

authorization of the manufacturer.

This product is patented and its trade mark registered. The manufacturer reserves the right to modify the product specifications without prior notification.

10.2. SERVICE

If the instrument does not work properly, before returning, check the cables and replace them, if necessary. Should the instrument still operate improperly, check that the operation procedure is correct and corresponds to the instructions given in this manual.

If the instrument is to be returned, its transportation is at the customer’s expense. Shipping instructions may be obtained by contacting the factory. A Return Material Authorization (RMA) number must be obtained from the factory prior to return.

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GP-2 GeoTest

A report should accompany the returned product, stating the reason(s) for return. The unit should be packed in its original carton or equivalent; any damage that may be due to non-original packing shall be charged to the customer. The manufacturer disclaims any responsibility for damages caused to people and/or objects.

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GP-2 GeoTest

11. PRACTICAL REPORTS FOR ELECTRICAL TESTS

11.1. EARTH RESISTANCE MEASUREMENT

PURPOSE OF THE TEST

This test is carried out to make sure that the protective device is coordinated with the earth resistance value. You cannot take off hand a limit earth resistance value as a reference for the test result: occasionally you must make sure that the prescribed coordination is respected.

EQUIPMENT PARTS TO BE TESTED

The earth equipment and its working conditions. The test must be carried out without disconnecting the earth references.

ADMISSIBLE VALUES

The earth resistance value, however measured, must meet the following requirement:

RE < 50 / I

where: RE= measured resistance of the earth equipment. The value can be

determined with the following tests:

- earth resistance with 3-wire voltmetric method

- loop impedance (see (*))

- 2-wire earth resistance (see (**))

- 2-wire earth resistance in the socket (see (**))

- earth resistance given by the contact voltage Ut (see (**)).

- earth resistance given by tripping time of RCDs (A, AC), RCD S (A, AC) (see (**)).

Ia= tripping time in 5s increments of the automatic switch; nominal tripping

current of the RCD (in case of RCD S 2 I∆n).

50= Limit safety voltage (reduced to 25V for special places). (*) In presence of an RCD the test must be carried out on the RCD

upstream or downstream, bypassing it to avoid its intervention.

(**) These methods, even if not yet prescribed for by the CEI 64.8 standard,

give values which many 3-wire comparison tests proved to be revealing for earth resistance.

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GP-2 GeoTest

Black

Green

Use several rods in parallel and

EXAMPLE OF EARTH RESISTANCE MEASUREMENT

You must test equipment protected by a RCD at 30 mA. Measure the earth resistance according to one of the above-described methods. In order to check whether the resistance complies to the standards in force, multiply the value for 0.03A (30 mA). If the result is lower than 50V (or 25V for special places) the equipment is to be considered as coordinated as it meets the above stated requirement.

In case of RCDs at 30 mA (used for nearly the totality of civil equipment) the maximum earth resistance admitted is 50/0.03=1666###. This also permits use of the simplified methods described, which give an approximate value (although not extremely precise) for the calculation of the coordination.

VOLTAMPEROMETRIC METHOD For small earth plant

Let a current circulate between the earth rod and a current probe positioned at a distance from the earth equipment outline corresponding to five-times the diagonal of the area delimiting the earth equipment (see Figure 5). Position the voltage probe halfway between the earth rod and the current probe, then measure the voltage between the two.

moisten the surrounding ground if the instrument is not able to supply the current necessary to perform the test because of an high earth resistance.

Figure 5: Earth resistance measurement (voltamperometric method

Red

Blue

for small earth plant)

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GP-2 GeoTest

Black

Green

For large earth plants

This procedure is also based on the voltamperometric method, but it is mainly used when it is difficult to position the auxiliary current rod at a distance corresponding to five-times the diagonal of the area of the earth equipment. Position the current probe at a distance equal to the diagonal of the area of the earth equipment (see Figure 6). To make sure that the voltage probe is positioned outside the area affected by the rod under test, take more measurements, first positioning the voltage probe halfway between the rod and the current probe, then moving the probe both towards the earth rod and towards the current probe.

Use several rods in parallel and moisten the surrounding ground if the instrument is not able to supply the current necessary to perform the test because of an high earth resistance.

Red

Blue

Figure 6: earth resistance measurement (voltamperometric method for big earth

plant)

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GP-2 GeoTest

Black

Green

2nd measurement:

11.2. EARTH RESISTIVITY MEASUREMENT

PURPOSE OF THE TEST

This test is intended to analyze the resistivity value of the ground in order to define the type of rods to be used.

EQUIPMENT PARTS TO BE TESTED

For the resistivity test admissible values do not exist. The various values measured by positioning the rods at growing distances “a” must be quoted in a graph. According to the resulting curve, suitable rods will be chosen. As the test result can be affected by metal parts buried (such as pipes, cables or other rods), in case of doubt take a second measurement positioning the rods at an equal distance "a", but rotating their axis by 90°.

compared to the previous measurement the rods are rotated by 90°.

1st measurement: the rods are positioned at a distance “a”

90°

aaa

Blue

Red

The resistivity value is calculated with the following formula:

where: ρ= specific resistivity of the ground (Ωm)

ρ=2πaR

a= distance between the rods (ft/m)

R= resistance measured by the instrument (Ω)

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GP-2 GeoTest

The measuring method allows definition of the specific resistance up to the depth approximately corresponding to the distance “a” between the rods. If you increase the distance “a” you can reach deeper ground layers and check the ground homogeneity. After several ρ measurements, at growing distances “a”, you can trace a profile like the following

ones, according to the most suitable rod chosen:

Curve1: as ρ decreases only in depth, it is possible to use only a rod in depth. Curve2: as ρ decreases only until the depth A, it is not useful to increase the depth of the

rod beyond A. Curve3: even at a superior depth, ρ does not decrease, therefore a ring rod must be used.

(Ωm)

(ft / m)

APPROXIMATE EVALUATION OF THE CONTRIBUTION OF INTENTIONAL RODS (6412 2.4.1)

The resistance of a rod Rd can be calculated with the following formulas (ρ = average resistivity of the ground).

a) resistance of a vertical rod

Rd = ρ / L

L= length of the element touching the ground

b) resistance of an horizontal rod

Rd = 2ρ / L

L= length of the element touching the ground

c) resistance of linked elements

The resistance of a complex system with more elements in parallel is always higher than the resistance which could result from a simple calculation of elements in

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GP-2 GeoTest

parallel, especially if those elements are close and therefore interactive. For this reason, in case of a linked system the following formula is quicker and more effective than the calculation of the single horizontal and vertical elements:

Rd = ρ / 4r

r= radius of the circle which circumscribes the link.

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AMPROBE

MIAMI, FL Tel: 305 423 7500 Fax: 305 423 7554 www.amprobe.com

Tecnical Support:

www.amprobe.com

800 327 5060

Amprobe GP-2A Operating Manual

Specifications and Main Features

Frequently Asked Questions

User Manual