User manual AMPROBE GP-2 GEOTEST

[. . . ] EN - 1 GP-2 GeoTest Instruction Manual GP-2 GeoTest GP-2 GeoTest 1. PRECAUTIONS AND SAFETY MEASURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. 1. PRELIMINARY INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 DURING USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] 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 F F Drive the 4 earth rods into the ground at the same distance D. 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. Insert the 4 connectors (black, red, blue and green) of the cables into the corresponding input terminals of the instrument (E, S, H, ES). Connect the alligator clips as shown in Figure 4. E CAT III 440 V 250 V P-N-PE S ES H H a a a Figure 4: 4 wire earth resistivity measurement EN - 15 GP-2 GeoTest F Position the switch on . Display appearance: --DIST ft or m 0 V 010 ft/m 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 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 t s Press s or t to select the value of the parameter D: 006 ft or m ft/m Value of the parameter D ESC Press ESC to confirm the value previously set. GO 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. 5 Measured earth resistivity value Measurement unit: m EN - 16 GP-2 GeoTest 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 m 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). AVG 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 700 is not inserted in the calculation of average value. Example: 1st measurement Main display: 6. 6 m Secondary display on the right-hand side: empty 2nd measurement Main display: 26 m Secondary display on the right-hand side: Add Press AVG: main display: 16. 4 m 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 km Secondary display on the right-hand side: Add Press AVG: main display: 16. 4m secondary display on the left-hand side: 2 secondary display on the right-hand side: Add ESC Use ESC to leave the screen showing the average value and return back to the screen corresponding to the last measurement taken. EN - 17 GP-2 GeoTest SAVE Example: Press SAVE to store the test results in memory (see paragraph 5. 1). You position the rods at a distance D of 3 feet and take 3 resistivity measurements: 7. 7 m 7. 1 m 7. 1 m A dd A dd 1st meas. 2nd meas. 3rd meas. a) 1st measurement: you see the measured value but not 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. 4 002 m This screen appears after press in AVG Add A The "002" indicates that 7. 4m 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. c) 3rd measurement: as with point b) above, but the average value is calculated as average between the three values measured. 7. 3 003 m This screen appears after pressing AVG Add A The "003" indicates that 7. 3m is the average value calculated as average between the three values previously measured. EN - 18 GP-2 GeoTest 4. 4. ANOMALOUS SITUATIONS WHICH CAN OCCUR DURING TESTS F 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. rP indicates an high resistance value. F 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. [. . . ] 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 / Ia 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= 50= (*) (**) tripping time in 5s increments of the automatic switch; nominal tripping current of the RCD (in case of RCD S 2 In). [. . . ]