HỘI NGHỊ KHOA HỌC TOÀN QUỐC VỀ CƠ KHÍ – ĐIỆN – TỰ ĐỘNG HÓA
(MEAE2021)
Design, make and install a test-rig for testing 660V/1140V
earth leakage protective device
Nguyen Thac Khanh 1,*, Kim Ngoc Linh 1, Nguyen Truong Giang 1, Bui Minh Dinh 2
1 Hanoi University of Mining and Geology, Vietnam
2 Hanoi University of Science and Technology, Vietnam
ARTICLE INFO ABSTRACT
Article history:
th In order to determine the specifications of a leakage current protective
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un 2021 device, an appropriate test-rig is required. Currently, in Vietnam, there is
Accepted 16th Aug 2021 no facility that has such a test-rig. With the financial support from the
Available online 19th Dec 2021 project KC.05.24.6/20, the group of authors participating in the project
have successfully designed, made and installed a test-rig for testing
Keywords:
test-rig, short-duration 660V/1140V earth leakage protective device. This test-rig allows to
determine most of the characteristic parameters of a leakage protective
leakage current, tripping device used in underground mines such as symmetric and asymmetrical
resistance, single phase leakage resistance, long-time leakage current, short-duration leakage
leakage current, operating time. The test-rig also allows to evaluate: the efficiency
of the capacitive component compensation circuit of the leakage current;
circuit that automatically detects and shunted the leakage phase; the
effect of the back e.m.f of the large motor on the leakage current; allows
build the characterization of the protective device.
Copyright © 2021 Hanoi University of Mining and Geology. All rights reserved
1. Introduction and calibrating the type АЗУР protective device) ,
the goal set for the test-rig must be to allow the
The design and manufacture of electrical
following types of tests to be performed: value of
equipment used in underground mines has very
tripping resistance when single-phase or
high requirements for testing procedures. The
symmetrical three-phase leakage, long-term
objective of the project KC.05.24.6/20 is to design
leakage current value, short-duration leakage
and manufacture a leakage current protection
current value, the operating time of the
device with a voltage of 660/1140V that meets
equipment when a single-phase leak through a 1
the technical requirements according to
KΩ resistor, the effect of the back electromotive
TCVN7079, capable of automatically detecting
force of the motor when the power is cut off and
and connecting leakage phase short circuit,
the characterization of the leakage protection
ensure capacitance current compensation
device.
according to voltage 660/1140V. To achieve the
project’s goals, one of the first things to be 2. Test-rig building results
considered is to build a test-rig. On the basis of 2.1. Design the schematic diagram of the test-
studying the requirements of the leakage current rig
protective device test, with reference to
international test equipment (Stand for testing
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HỘI NGHỊ KHOA HỌC TOÀN QUỐC VỀ CƠ KHÍ – ĐIỆN – TỰ ĐỘNG HÓA
(MEAE2021)
In order that the test-rig can be used for the single-phase leakage resistance is selected
testing earth leakage protective device at two according to criteria: Total single-phase leakage
voltage levels, 660V and 1140V, the substitution resistance to earth is about 100 KΩ; two
insulation resistance is selected according to the resistance levels corresponding to the single-
following criteria: Total insulation resistance per phase leakage tripping resistance with
phase about 200 KΩ; two values of tripping deformation characteristic of 20 KΩ (660V
resistance corresponding to the symmetrical network) and 50 KΩ (1140V network) must be of
three-phase leakage are 30 KΩ (660V network) high accuracy class and can work long-term in
and 60 KΩ (1140V network) must be the type heavy conditions, especially when there is a leak;
with high accuracy and can work for a long time in 1 KΩ leakage resistance equivalent to human
the heaviest conditions when there is a leak; it is resistance when touching one phase of the
necessary to have small value resistors, high network must be high power rating, capable of
accuracy class, long-term working in leakage long-term work in the case of the heaviest leakage
conditions to correct or take test signals when (1-phase leakage through a 1 KΩ resistor when
necessary; the insulation resistance of each phase the network has the insulation resistance near the
relative to earth can be easily varied over a tripping resistance and the capacitance of the
narrow or wide range in order to develop the network equal to the limited value is 1uF); need
characteristic of the leakage protective device. small value resistor, high accuracy grade, long-
The capacitance of each phase to ground is term working in leakage condition to correct or
replaced by five 1uF/1600V capacitors connected take test signal when necessary; The single-phase
in series. The equivalent capacitance of each leakage resistance can be easily varied over a
phase relative to ground can be varied by means wide range to develop the characteristic of
of plugs at 5 levels of 0.2uF (5 capacitors in leakage protection.
series); 0.25uF (4 capacitors in series); 0.33 (3 From the above results, the schematic diagram
capacitors in series); 0.5uF (2 capacitors in series) of the experimental circuit test-rig of the
and 1uF (3 capacitors short). 660V/1140V power network leakage current
Similar to the insulation resistance and protection device in the laboratory is designed as
capacitance test-rigs, so that the test-rig can be shown in Figure 1.
used for testing leakage current protective
devices at two voltage levels of 660V and 1140V,
_____________________
* Corresponding author
E - mail: nguyenthackhanh@humg.edu.vn
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HỘI NGHỊ KHOA HỌC TOÀN QUỐC VỀ CƠ KHÍ – ĐIỆN – TỰ ĐỘNG HÓA
(MEAE2021)
~ 380V ~ 660V(1140V) MC
A A1
B B1
C C1
CD 10 KVA Trans.
CC
K ro K1A K1B K1C K 2 A K 2B K2C
R R R
V mA A B C
Rro1pha
CA CB CC
R 120k 120k R 120k R
30k ro10 RA10 B10 C10
CC R C C
10k Rro9 10k RA9 10k RB9 10k C9 A5 CB5 C5
A B C1
1 1 1 1 1
10k R 5,6k R 5,6k R 5,6k R
EARTH ro8 A8 B8 C8
R
LEAKAGE 1k Rro7 1k RA7 1k RB7 1k C7 CA4 CB4 CC4
RELAY 1 1 1
1k R 1k R 1k R 1k R
UNDER TEST ro6 A6 B6 C6
CA3 CB3 CC3
1k R 1k RB5 1k R
1k Rro5 A5 C5 1 1 1
100 R 100 R 100 R 100 R
ro4 A4 B4 C4 C C
CA2 B2 C2
1 1
30k Rro3 30k RA3 30k RB3 30k RC3 1
10k Rro2 100 RA2 100 RB2 100 RC2 CA1 CB1 CC1
1 1 1
10k Rro1 30k RA1 30k RB1 30k RC1
Earth
Figure 1. Schematic diagram of the test-rig of the 660V/1140V leakage current protection device
2.2. Design, fabrication and installation of test- In laboratory conditions, in order to be able to
rigs investigate the effect of back electromotive force
of the motor when the power is cut off to the
To create a 660V (or 1140V) three-phase
leakage current, a back electromotive force
power network with isolated neutral voltage, use
generator has been designed and manufactured
a three-phase transformer to convert the mains
as shown in Figure 3. To generate the back
voltage in the laboratory from 380V to 660V
electromotive force of the motor when the power
(1140V). The transformer is a 380V/660 (1140V)
is cut off, the authors use a 2.2kW permanent-
isolated three-phase transformer with a capacity
magnet synchronous motor with direct starting
of 10kVA, taking power from 380V through the
type LSPMSM, voltage 380V and another 10 kVA
isolating circuit breaker CD. 10kVA transformer,
isolated three-phase transformer, with voltage of
switching devices and measuring instruments are
380/660/1140V.
installed in the electrical enclosure as in Figure 2.
Figure 2. Internal structure of the electrical Figure 3. Devices for generating back e.m.f of the
enclosure motor when the power is cut off
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HỘI NGHỊ KHOA HỌC TOÀN QUỐC VỀ CƠ KHÍ – ĐIỆN – TỰ ĐỘNG HÓA
(MEAE2021)
2.3. Test-rig correction
After installing the test-rig, measured,
calibrated and determined the actual parameters
of the test-rig.
• Measure the resistance and capacitance
parameters of each phase against ground
The results of measuring the parameters of the
resistance and capacitance equivalence model
from phases to the ground of the network are
presented in tables 1 and 2.
Figure 4. The 660V/1140V test-rig of leakage
current protection device
Table 1. Measurement results of insulation resistance from phases to ground
RA, KΩ RB, KΩ RC, KΩ Measuring instrument
Design value 198.8 198.8 198.8
Measured results 198.1 198.1 198.1 Sanwa LCR700
Table 2. Measurement results of insulation capacitance parameters from phases to ground
CA, uF CB, uF CC, uF Measuring instrument
0,2-1 0,2-1 0,2-1 Sanwa LCR700
• Measure and test single-phase leakage The results of the resistance measurement of
resistive loads the single-phase leakage resistance equivalent
test-rig are shown in Table 3.
Table 3. Single-phase leakage resistance measurement results
Design value 103.1 KΩ 1 KΩ 10 KΩ 20 KΩ 50 KΩ
Measured results 102.9 0.999 9.9 19.63 49.8
2.4. Test-rig Manual
For a leakage resistance equivalent to 1 KΩ,
tested at 400mA leakage current condition, After the test-rig for testing leakage current
capable of operating for not less than 30 min. protective devices 660V/1140V has been
• Measure and check the test-rig in the live designed and installed completely in the
state of 1140V Laboratory of the University of Mining and
Proceed to supply 380V main power to the Geology, the authors have compiled detailed
transformer. Measure the voltage of the phases to instructions for use test-rig. Figure 5 is an
earth in 3 cases: normal working, single-phase example illustrating test-rig connection
leak through the 20 KΩ resistor and single-phase instructions for testing the tripping resistance
leak through the 1 KΩ resistor. when three-phase symmetrical leakage of 660V
power network.
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HỘI NGHỊ KHOA HỌC TOÀN QUỐC VỀ CƠ KHÍ – ĐIỆN – TỰ ĐỘNG HÓA
(MEAE2021)
Test-rig for testing 660V/1140V earth leakage protective device
~ 380V ~ 660V(1140V) MC
A A1
B B1
C C1
CD 10 KVA Trans.
CC
K ro K1A K1B K1C K 2 A K 2B K2C
R R R
V mA A B C
Rro1pha
CA CB CC
R 120k 120k 120k
30k ro10 RA10 RA10 RA10
CC C C
10k Rro9 10k RA9 10k RA9 10k RA9 A5 CB5 C5
A B C1
1 1 1 1 1
10k R 5,6k R 5,6k R 5,6k R
EARTH ro8 A8 A8 A8
LEAKAGE 1k Rro7 1k RA7 1k RA7 1k RA7 CA4 CB4 CC4
RELAY 1 1 1
1k R 1k R 1k R 1k R
UNDER TEST ro6 A6 A6 A6
C C C
1k R 1k R 1k R A3 B3 C3
1k Rro5 A5 A5 A5 1 1 1
100 R 100 R 100 R 100 R
ro4 A4 A4 A4 C C
TĐ CA2 B2 C2
1 1
30k Rro3 30k RA3 30k RA3 30k RA3 1
10k Rro2 100 RA2 100 RA2 100 RA2 CA1 CB1 CC1
1 1 1
10k Rro1 30k RA1 30k RA1 30k RA1
Tiếp đất
Figure 5. Connection of the test-rig to test the tripping resistance when three-phase symmetrical
leakage of 660V power network
Table 4 is the specification of the test-rig for 660/1140V earth leakage current protective device.
Table 4. Specifications of the test-rig
Input voltage, V 380
Output voltage, V 660/1140
Three-phase transformer capacity, kVA 10
Network capacitance change range, uF/pha 0-1
Symmetrical three-phase leakage resistance variation range, KΩ 0-198
Single phase leakage resistance variation range, KΩ 1-103
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HỘI NGHỊ KHOA HỌC TOÀN QUỐC VỀ CƠ KHÍ – ĐIỆN – TỰ ĐỘNG HÓA
(MEAE2021)
Measure the line voltage of the test network
using a HIOKI DT4254 digital multimeter. Single-
phase leakage current measurement using digital
millimeter HIOKI 3286-20. To measure the signal
pattern and determine the trip-time, use an
oscilloscope of the type TEKTRONIX MDO3014.
Below are some test results using the test-rig
for testing earth leakage protective devices.
Figure 8. Test results to determine the effectiveness
of the leakage-phase grounded solution
Figure 6. Experiment to determine the tripping
resistance of earth leakage protective device Figure 9. Test results to determine the effect of back
e.m.f of motor on leakage current
Figure 7. Test result for determining single phase Figure 18. Test results for determining the tripping
leakage current through a 1 KΩ resistor with back time of leakage current protective devices
e.m.f of load
3. Discussion
- The test-rig of leakage current protection
device in the Laboratory of Electrical and
Electronic Engineering of the University of Mining
and Geology allows to determine most of the
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HỘI NGHỊ KHOA HỌC TOÀN QUỐC VỀ CƠ KHÍ – ĐIỆN – TỰ ĐỘNG HÓA
(MEAE2021)
characteristic parameters of a leakage protection serving testing, calibrate leakage protection
device used in underground mines such as devices at production facilities.
symmetric and asymmetrical leakage resistance, 4. Conclusion
long-term leakage current, shot duration leakage
current, tripping time. The test-rig also allows to The test-rig for testing 660V/1140V earth
evaluate the efficiency of the capacitive component leakage protective device is the first test-rig in
compensation circuit of the leakage current, the Vietnam capable of testing to determine most of
automatic detection and short-circuit connection the specifications of a leakage current protective
of the leakage current, and the effect of the back device using in underground mine. The test-rig can
e.m.f of the large-capacity motor on the leakage be developed to be able to test leakage curret
current, perform to build the characterization of protective device use in underground mine power
the protective device. networks containing semiconductor converters
- With this test-rig, it also allows testing the (isolated ac/dc network).
results of new research directions on leakage
protection in underground mines such as testing References
insulation resistance by alternating current TCVN 7079, (2002). Tiêu chuẩn Việt Nam TCVN
measurement, active capacitance compensation, 7079 : 2002 - Thiết bị điện dùng trong mỏ hầm
asymmetrical capacitance compensation, negative lò (Vietnam Standard TCVN 7079 : 2002 –
capacitance compensation etc Underground mine electrical equipment).
- On the basis of the results of designing and
manufacturing test-rigs in the Laboratory, it is https://priborpostavka.ru/item/stend-dlya-
possible to go to research, design, and manufacture proverki-apparatov-azur.
test equipment of smaller and more compact size,
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