Sbe-8 Type Earth Resistance Meter

. Summary
SBE-8 Type analogous earth resistance meter's features are complete function, high accuracy, easy to operate and work stably, with built in generator. It is suitable for the field application.It can be utilized to measure the earth resistance of the earthing system of the electric system, electrical equipment, communication tower, high-rise buildings and others.Moreover, it also can be utilized to measure the resistance value of low-resistance conductor and the specific resistance of the soil.The GB/T7676-1998 standard is applicable to the the ZC-8 Type earth resistance meter.
.Specification, Performance and technical Index
1. Specification
Type
Measurement range (Ω)
Mini scale mark (Ω)
Auxiliary earth resistance (Ω)
Percent of accuracy (%)1000Ω0-100.1≤1000 30-1001≤2000 30-100010≤5000 3100Ω0-10.01≤ 50030-100.1≤1000 30-1001≤2000 32. Operating temperature and humidity : temperature (-20-40)ºC, relative humidity ≤80%.
3. Testing temperature and humidity: temperature (23ºC±5ºC), relative humidity ≤75%.4. The rated speed of handle : 120 rpm.5. Influence of tilting : If the 5 degree tilting of any direction occurs to the meter , the variation of indicator value should be less than 50% accuracy.6. Influence of external magnetic field: If the magnetic intensity of external magnetic field is 0.4kA/m, the variation of indicator value should be less than 100% accuracy.7. The insulation resistance : The resistance value should be more than 30 MΩ.8. The dielectric strength: The insulation between the circuit and housing can withstand 1kV 50Hz AC for 1 minute.9. The boundary dimension: L x Wx H(170x110x164)mm.10. Weight: 4.0kg (including the accessory). Main structure and Working Mechanism1. SBE-8 Type Earth Resistance Meter is consisted of the hand generator, current transformer, slide-wire potentiometer, galvanometer and other parts. All components are installed in the housing and the auxiliary probe and wire are put in the knapsack. It is very easy to carry the meter.2. The Working mechanism of this meter can be find in the figure. If the meter generator rotates at 120 rpm, it will output the AC voltage.
1.1. The *1 component can be replaced with 10k.2.2. The *2 component can be replace with 47k.3.3. The *2 component can be replace with 30k.
IV. Operating Instruction1. Measuring the earth resistance (Figure 1)
To the protected electrical equipmentSwitch offFigure 1
1.1The electric potential probe P' and current probe C' should be inserted straightly along the testing earth electrodes and the distance between them is 20 meter. The electric potential probe P is inserted in the middle of the the electric potential probe P and current probe C'.1.2 It should use the wire to connect the E', P' and C' to the corresponding terminal of meter.1.3 It should place the meter horizontally, and make certain the galvanometer is at the center line, or the galvanometer should be adjusted to the center line via using zero setting device.1.4 It should turn the handle multiplier to the max position and rotate the generator handle slowly; meanwhile, it turns the "measuring dial" and make the galvanometer pointer point to the center line.1.5 If the galvanometer pointer is closed to the balanced position, it should rotate the generator handle faster and let the speed reach 120 rpm as well as adjust the measuring dial and make the pointer point to the center line.1.6 If the reading of measuring dial is less than 1, it should turn the multiplying power scale to the smaller one and re-adjust the measuring dial so that the correct reading can be acquired.1.7 The earth resistance value can be acquired via using the reading of measuring scale dial to multiply the multiplying power of multiplying power scale dial.2. Measuring soil specific resistance(see figure 2)
2.1. The earth resistance meter with four terminal (1-10-100Ω, 0.1-1-10Ω) can be utilized to measure the soil specific resistance.2.2 The 4 probes should be buried in soil along a line and the distance between them is "acm". The setting depth of the probe should be less than 1/20 "a" distance.2.3 It should open C2 and P2 connector and connected to the corresponding probes by using 4 wires as indicated in figure 2. The measuring method is the same with the measuring earth resistance.2.4 Measuring specific resistance: P=2πaR; in this formula, "R" refers to the earth resistance reading, "a " refers to the distance (cm) between probes," P" refers to the soil specific resistance in that area. The specific resistance in the above figure can be regarded as the approximate average soil specific resistance between the probes.3. Measuring the conductor resistance (Figure 3)Figure 3
3.1 If it is the meter with three terminals, the P and C terminal should be short circuit and the measured resistance should be connected to the E terminal as well as P and C short circuit terminal.3.2 If it is the meter with four terminals, the C1 and P1 as well as C2 and P2 should be short circuit at first, the measured resistance should be connected to he short circuit terminals of C1 and P1 as well as C2 and P2.3.3. Making certain the earth resistance meter works normally:It should connect the C2 and P2 using the two ends of one longest wire that is 40 meter (or 20 meter) and is one of the accessories. And it should turn the handle multiplier to X1 position ( or X0.1 position) , rotate the generator handle at 120 rpm and turn the dial rotary knob to make the galvanometer pointer point to the "0" position. At this moment, the reading of the dial multiplies the multiplying power and the calculating result is the measured wire's resistance value( about 1.3Ω ~ 1.9Ω or 0.7~1Ω). If the result is the wire's resistance value, the meter works normally.
V. Notes1. If the galvanometer is too sensitive, the depth that dipolar probe are inserted into the soil should be shallowered; if the galvanometer's sensitivity is too low, it can inject the water into the soil around the probe.2. If the earth interfering signal is strong, it can speed up the rotation of hand generator to enhance the anti-jamming capability so that the steady reading can be acquired.3. If the distance between the earth electrode E' and current probe is more than 40 meter, the position of electric potential probe can be meters away from the line of E' and C' and its measuring error can be ignored. If the distance between the earth electrode E' and the current probe C is less than 40 meter, the electric potential probe P' should be inserted into the middle of the line formed by E' and C'.4.If the measuring earth resistance value is less than 1Ω, it should turn the SBE28 type earth resistance meter's handle multiplier to the minimal position (X 0.1), open the two connectors of E and connect a 5 meter (0.75mm2) wire to the measured objects so that the additional resistance resulted from the connecting wire resistance can be eliminated. (See figure 4)Figure 4VI. Transportation and Storage1. The meter should be handled with care and avoid the violent or long-term vibration during transporting and storing so that the meter axle tip will not be damaged and the accuracy is ensured.2. If the meter is not be used, it should be stored indoor. The ambient air temperature must not be too cold or too hot. It must not be place on the dirty and humid ground and in the corrosive gas ( like acid or alkali steam).VII. Warranty1. The manufacturer should freely repair or change the meter and notify the sales department on condition that the meter can not work normally and the user strictly comply with the specification in the manual and the factory seal is complete.2. The manufacturer has the right to change the structure of meter without notification.. Complete equipment1. earth resistance meter one pcs2. auxiliary probe two pcs3. wire 5m, 20m and 40m one pcs for each length4. Operating manual one pcs5. product certificate one copy