Real-time Measurement for Controlling Grounding Resistance

Ismujianto

, A. Damar Aji

, Isdawimah

, Nuha Nadhiroh

Department of Electrical Engineering, Politeknik Negeri Jakarta, Depok, Indonesia

Keywords: Grounding resistance, real-time, monitoring system, LabVIEW

Abstract: Grounding is the protection system that is useful for transferring the leakage current from an electrical system

to the ground through a grounding electrode buried in the ground. Types of grounding electrodes can be in

the form of rod electrodes, plate electrodes, mesh-connected electrodes or other forms. In order for the

grounding system to function properly, it must be ensured that the grounding system has very small earth

resistance, close to zero. In addition, earth resistance value is influenced by soil resistivity, mineral content,

soil moisture and temperature particularly due to weather changes. Indonesia has two seasons, the dry season

and the rainy season. During the dry season, soil temperatures increase, causing the soil to dry up and the

earth resistance to increase as well. Therefore, to prevent an increase in the value of earth resistance due to

weather change, a grounding system that can be monitored and controlled automatically is needed. The

proposed grounding resistance monitoring system is developed in LabVIEW environment. The voltage

applied to the electrodes will cause current to flow to the ground, so the earth resistance value can be

measured. Experimental results show that the earth resistance value can be measured in real-time, and the

data obtained can be used as feedback to control the earth resistance value.

1 INTRODUCTION

In an electrical system, the safety of equipment

and users or operators against leakage currents and

the danger of thunder is the first priority (Vilacha,

Otero, Moreira, & Miguez, 2015). Therefore, an

grounding system must be used as part of a safety

system. Grounding system is a system that is

intentionally made to connect parts of the equipment

that are secured with a grounded conductor, to

prevent the touch voltage being too high (Lee, Chang,

& Jiang, 2015).

The main purpose of the earthing system is to

provide safety for the system and the personnel

involved in it. There are two main things in the

grounding system, namely a grounding system must

have a ground resistance value close to zero and

prevent potential differences (voltage) between the

electrical system and other elements during

operation(Caetano, Lima, Paulino, Boaventura, &

Cardoso, 2018). In the electrical system, to provide

protection for components from damage caused by

high voltage and leakage currents, a good isolation

and grounding system is needed (Androvitsaneas,

Alexandridis, Gonos, Dounias, & Stathopulos, 2016).

The distance between the grounding electrodes is

one of the important subjects in the design of the

earthing system(Harid et al., 2015; IEEE Guide for

Improving the Lightning Performance of Electric

Power Overhead Distribution Lines, 1997). The

greater the distance between the earth electrodes, the

earth resistance value is also greater. In this study,

another important subject is the depth of the

electrodes burial. The deeper, the smaller the earth

resistance value(Garip & BAL, 2014; Powering and

Grounding Electronic Equipment, 2005).

Some grounding methods that have been

developed at present are the use of grounding

electrodes, associated grounding systems, meshed

(mesh) grounding systems, and plate grounding

systems(Guo et al., 2014).

The amount of grounding resistance value

depends on the specific soil resistance at that location

and the type and dimensions of the grounding system

installed. A location makes it possible to have

different soil structure, both horizontally and

vertically(Clark et al., 2014).

Increasing the value of grounding resistance can

pose a risk to human safety or components in the

system(Clark et al., 2014). To prevent this situation,

there are many different ways to reduce the resistance

120

Ismujianto, ., Aji, A., Isdawimah, . and Nadhiroh, N.

Real-time Measurement for Controlling Grounding Resistance.

DOI: 10.5220/0009910800002905

In Proceedings of the 8th Annual Southeast Asian International Seminar (ASAIS 2019), pages 120-125

ISBN: 978-989-758-468-8

value between grounding electrodes and the surface

touch ground. To get the ideal grounding conditions

studies need to be conducted to meet the standard

earth resistance values(Jafari, Kanabar, Member, &

Sidhu, 2019).

In this study, a grounding resistance measurement

method is applied continuously, so that resistance

values can be monitored in real time. Not only

grounding resistance data, ambient temperature is

also measured. The monitoring results will be used as

a baseline in controlling ground resistance values to

overcome changes in grounding resistance values due

to weather change.

2 SYSTEM ESTABLISHMENT

Grounding resistance plays a large role in

planning a good earthing system. The most effective

method of improving the quality of a grounding

system is to make the ground resistance value (R

) as

small as possible, ideally zero ohms(Mohos &

Ladanyi, 2015; Saleh et al., 2015). This R

value

depends on the resistivity of the soil type (ρ), the

length of the ground electrode (L) and the cross-

sectional area (A) of the ground

electrode(Shariatinasab & Gholinezhad, 2017;

Yamamoto, Yoshioka, Sumi, Yanagawa, & Sekioka,

2015). The value of R

on the ground rod is expressed

in the following equation:

(1)

According to the equation above, one of the most

influential factors in determining the value of Rg is

the factor ρ. The value of ρ is influenced by soil

conditions, where the more moist the smaller the ρ is.

Not only that, the resistance value of soil types is also

influenced by acidic pH, soil temperature, salt

content, soil density, weather, and soil type.

In addition, the Rg value can be improved by

enlarging the cross-sectional area, namely by

changing the shape of the ground rod to the shape of

the ground mesh(Kumar & Bharadwaj, 2015). R

value on the ground mesh is equal to:

(2)

In this study measurements of ground resistance

at 2 grounding points that have been buried and not

connected to the lightning protection system. The

grounding system used in this research is a ground

mesh system installed in the area of the Jakarta State

Polytechnic Electrical Engineering Laboratory as

shown in Figure 1. Both grounding points are buried

at the same depth, which is 1.5 meters, and have the

same soil conditions. At the first point no treatment

was added to the burying of the ground mesh, while

at the second point the addition of bentonite powder

was made to reduce the ground resistance

value(Manikandan, 2015). Therefore, 2 different

earth resistance values are obtained.

Figure 1. Ground Mesh Location and Wiring

The system developed in this study is in

accordance with the working principle of the earth

tester meter, as shown in Figure 3. The P electrode is

mounted as far as 10 meters from the earthing point,

while the C electrode is mounted as far as 20 meters

from the earthing point. Then the measurement of

earth resistance is made using the inline method. The

current is injected into the earth electrode circuit with

2 auxiliary electrodes, then voltage measurements are

taken. The results of the measured voltage

distribution (V) and the injected current (I) show the

value of Rg, as stated in the following equation:

(3)

Figure 3. Earth Tester Configuration

Real-time Measurement for Controlling Grounding Resistance

121

2.1 Hardware

The implementation of the measurement of

grounding resistance continues is developed in the

LabVIEW environment. LabVIEW is a programming

language in the form of graphical languages (Nicola

et al., 2016). This graphical language, like visual

basic, can be used to conduct data acquisition and

analysis. Figure 4 shows the hardware system

architecture in this study.

Figure 4. Hardware Architecture

National Instrument Data Acquisition Card (NI-

cDAQ) 9174 is used to carry out physical data

acquisition such as injection of current, voltage and

temperature (NI cDAQ

-9174 NI CompactDAQ

Four-Slot USB Chasis, 2013). The NI-9265 module

is a current output module(NI 9265 Datasheet, 2015).

Each analog channel has a DAC (digital-to-analog

converter) that can produce current injection. NI-

9219 module is a 4-channel C series universal analog

input module that can be used to measure voltage(NI

9219 Datasheet, 2017). Whereas NI-9211 is C series

temperature input module which is used to measure

ambient temperature(NI 9211 Datasheet, 2015).

The three physical parameters (current, voltage

and temperature) are then acquired by NI cDAQ -

9174. cDAQ communicates with personal computers

via USB cable type B. So users can obtain data in real-

time and continuously. The working principle of this

system is in accordance with the working principle of

the grounding resistance meter as explained above.

Figure 5 shows the use of the NI-module in this study.

2.2

Software

In principle, the software developed in this study,

reads all measurements taken. Communication

between software and hardware takes place through

Ni CDAQ-9174.

Figure 6 shows the software flowchart.

Programming is divided into 2 parts, namely the data

acquisition process and the data logging process. In

the data acquisition process, after being given an

injection of current to the ground of 15 mA, the

measured voltage will be averaged every 10

measurements, so that Vmean is obtained.

Temperature measurements are carried out to

determine the ambient temperature when measuring.

Because the characteristics of temperature change are

very slow, no average temperature is needed. The

output of the data acquisition process is the earth

resistance value at both points (R

and R

) and

ambient temperature (T). The obtained data processed

in the form of time function waveform graphs.

(a)

(b)

Figure 5. NI module installation (a) side view (b) top view

Data logging process is the process of storing data

in the form of a .txt file. Data storage is done in 1

minute intervals. Measuring ground resistance has

been carried out for several days in October 2019.

The output of this data logging process is a

spreadsheet file containing measurement data, as

shown in Figure 7.

ASAIS 2019 - Annual Southeast Asian International Seminar

122

Figure 6. Flowchart of the Software

Figure 7. Spreadsheet file from data logging

3 RESULTS AND DISCUSSION

Real-time measurement of grounding resistance

software successfully shows and records the earth

resistance value, as shown in Figure 8.

Figure 8. Display of Measurement Software

On the front panel, it can be seen the date of

measurement, the magnitude of grounding resistance

at points A and B (R

and R

), and ambient

temperature (T). Not only that, the three physical

parameters are displayed in the waveform graph. The

front panel is also equipped with a "Reset" and "Save

Data" button. The reset button functions to repeat the

measurement, while the save data button must be

activated if the data is stored according to the

specified folder directory.

The continuous testing of the performance of the

grounding measurement system was carried out

during October 2019. The measurement results are

shown in Figure 9 and Figure 10.

Figure 9. Graphic of R

and R

Figure 10. Value of Ambient Temperature

Real-time Measurement for Controlling Grounding Resistance

123

Based on the graph above, the average value

during measurements in October showed an R

value of 23.2 Ohms; R

of 20.4 Ohms; and ambient

temperature of 28.2

C. Grounding resistance value is

still very high, this is because special controlling

treatments have not been done to reduce the value of

earthing resistance. The R

value is greater than the

value due to the addition of bentonite at point B.

In figure 10, ambient temperature does not show a

significant impact on the measurement of grounding

resistance.

In general it can be stated that the measurement

system developed in the study works well, so that it is

able to measure the value of earth resistance at both

points. Measured data, it can be recorded at intervals

every 1 minute.

4 CONCLUSIONS

In this study, the development of a real-time and

continuous grounding resistance measurement

system shows excellent results. The measurement

system was developed in LabVIEW language and

uses a reliable sensor module and output module.

From the data taken, it is found that the earth

resistance at both earthing points is still far from

ideal, the R

of 23.2 Ohms; R

of 20.4 Ohms. In

subsequent studies the data obtained can be used as

feedback to control the grounding resistance value.

ACKNOWLEDGEMENTS

This research was funded by the Jakarta State

Polytechnic under contract number 215 / PL3.18 / PN

/ 2019 in the Decentralized Research Program "Skim

Penelitian Produk Terapan".

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