Major tech MT330 Instruction Manual - Page 8

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9. SIMPLIFIED EARTH RESISTANCE MEASUREMENT METHOD

1. This method is recommended where an earth resistance higher than

10Ω is measured or where it is not possible to drive auxiliary earth

spikes. An approximate value of earth resistance can be obtained by the

two wire system where is shown in Fig. 2.

2. Rotary to function switch to "EARTH VOLTAGE" position and press to

test. Make certain that earth voltage is less than 10V.

3. First rotary the function switch to "200Ω" position and press to test, read

earth resistance. If the display shows "1" (MSD), switch to "2000Ω"

position and read earth resistance.

4. The reading obtained (Rx) is an approximate earth resistance value.

There is no need for external shorting as P and C terminals are shorted

by using the test leads specified for the Simplified measurement.

5. Rx = Re – re

Rx = True Earth Resistance

Re = Indicated Value re = Earth Resistance of Earth Electrode

6. Since measuring current is as low as 2 mA, the earth leakage breaker

(ELCB) does not trip even if the earth side of the commercial power

supply with an ELCB is used.

* Follow the proper connection such as Fig1.

1. Set the function switch to the highest 1000V DC (

position.

2. Insert the black test lead banana plug into the negative COM jack.

3. Insert the red test lead banana plug into the positive V jack.

4. Touch the black test probe tip to the negative side of the circuit.

5. Touch the red test probe tip to the positive side of the circuit.

6. Read the voltage in the display.

DC/AC VOLTAGE MEASUREMENTS: If the polarity is reversed, the

display will show (-) minus before the value

) or 750VAV (~)