Earth Tester

PRECIOHM ET – EARTH TESTER

Taurus Powertronics – Training

Taurus Earth Tester

1/3/2011Taurus Confidential Document

Earth Tester


Current Terminal

Potential Terminal-P1

Potential Terminal-P2

Earth Terminal

Range Selector

RS 232 Port

Mains Switch

Power ON

Memory

Battery Indication

Reset Set Print

Salient Features

Fall-Potential method of Earth Resistance Wenner method for Soil Resistivity measurementHigh dynamic measurement range of 0.01Ω to

20kΩDigital display in Ω with accuracy of ±2%Complete suppression of induction and leakage

power frequencies & its harmonics.Modular with in-built rechargeable batteryAvailable in models of 0–2kΩ & 0-20kΩCompact, portable, AC mains & battery operatedHoused in IP67 pelican casing


SOIL RESISTIVITY


Factors to be considered

Temperature

Humidity

Type of Soil

Strata of the Soil

Depth of Peg insertion


Principle of Operation– Soil Resistivity


Wenner 4 Pole Method

a a ab

V

I

ρ = 2πa

ΔvI

ρ = 2πaR

ρ = Resistivity (Ω-m) a = Probe Spacing (m)Δv = Voltage Measured

(volts) I = Injected current (Amps) R = Measured resistance

(Ω)

a = 10*b

Principle of Operation

Soil Resistivity Measurement: Four pole - Wenner Method A constant current with low frequency (128Hz) is

passed to current terminal The voltage across potential terminals P1& P2 is

measured Soil Resistivity is calculated using formula ρ = 2пaR


Schematic Diagram


Wenner 4 Pole Method for Soil Resistivity Measurement

a a ab

a = 10*b

P2P1E C

Operating Procedure

Soil Resistivity Measurement Install four terminals in the ground equally spaced

in a straight line Using the connecting cables, connect the E, P1,

P2 and C terminals to the corresponding electrodes.

Press the SET button and read the digital display. Record the reading at the appropriate location Using the obtained R-value, calculate the value of

resistivity (ρ), which is represented by the units of Ω-m (Ohm-Meter)


Soil Resistivity Measurement Testing Layout


a a ab

P2P1E

EP

1P

2

C

C

a

a

a

b

P2

P1

E

C

Building A Soil Resistivity Profile

A minimum of 3 direction of testing

Property line

ρx

ρy ρz

ρx + ρy + ρz 3

ρ =

SUB STATION EARTH MEASUREMENT


Principle of Operation—Earth Resistance


Distance of potential probe in meters

Ground Electrode Potential

probe (P) Current probe (C)

Current probe resistance

Ground probe resistance 61.8%

CXRes

ista

nce

in

ohm

s

Three pole -Fall Potential Method

Principle of Operation

Earth Resistance Measurement: Three pole -Fall Potential Method A constant current with low frequency (128Hz) is

passed to current terminal The voltage across potential terminal P1& earth

terminal measured The resistance is calculated using formula R =


VI

Schematic Diagram


d

3 Pole Method for Earth Resistance Measurement

d

h < 5% * d

h

Substation Earth Pit P2 C

Operating Procedure

Earth Resistance Measurement Connect equipment earth terminal to the station

earth pit Potential terminal to centre peg at distance 30m

from the earth pit Current terminal to current peg at distance 60m

from the earth pit The depth of penetration is less than 5% of the

distance between the pegs All the pegs are connected in straight line


Case Study


Case Study – PGCIL-NR ІІ

Place: Sonepat (PGCIL -NR ІІ)Date: 11/12/2010Substation: 400/220 kV S/s Powergrid,

MohanaContact Person: Mr. Shrivastava, Manager

Mr. Anil Kumar, DT Customer Requirements

Repeatability of the values & Heavy duty battery

Readings


Earth Pit Resistance R 0.90 Ohms

Soil Resistivity 5.1 Ohm-meter


Place: Nalagarh (PGCIL -NR ІІ)Date: 13/12/2010Substation: 400/220 kV S/s Power Grid,

ReruContact Person: Mr. Manish Gandotara,

Manager Mr. Vikram Sarochaya,

Engineer Readings


Earth Pit Resistance R=(Pit connected to grid)

0.60 Ohms

R= ( Individual earth Pit) 36.5 Ohms

Soil Resistivity 16.48 Ohm-meter


Place: Banala (PGCIL -NR ІІ)Date: 14/12/2010Substation: 400/220 kV S/s PowerGrid,

JhiriContact Person: Mr. Amit Kumar,

Sr.Engineer Mr. Pravesh Kaundal,

EngineerReadings


Distance ‘A’meters

Resistance ‘R’ Ohms

ResistivityOhm-meters

Location A 5 6.55 205.67

Location B 4 25.5 640.56

Location C 4 24.5 615.44


Place: Chamba (PGCIL -NR ІІ)Date: 16/12/2010Substation: 400/220 kV S/s Power Grid,

Sultanpur

Contact Person: Mr. Manish Sharma, Chief Manager

Mr. Mahendra Kaloria, Engineer

Readings


Earth Pit Resistance R=

2.5 Ohms

Soil Resistivity 138 Ohm-meter

Q & A


Earth Tester

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