Design, make and install a test-rig for testing 660V/1140V earth leakage protective device

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 253 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 254 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 255 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. 256 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 1-103 257 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 258 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, 259