Integrated Power Company, Moscow, Russia:

S. I. Malafeev, Chief Researcher, Doctor of Engineering Sciences, sim_vl@nm.ru
A. V. Anuchin, Engineer

The article addresses the method to control insulation resistance in DC mains with adjustable voltage and variable polarity based on the each bus leakage test and calculation of the resistances. Each bus is connected to a grounded element via the series-connected diode and precision resistor. In case of the insulation fault in a bus, current flows in the precision resistor connected to another bus if it has a positive potential. By the value of this resistor voltage and the mains voltage, the insulation resistance is calculated with the help of a controller. The instrumental error depends on the mains voltage error, precision resistor voltage error and the insulation resistance. The instrumental error lowers with the insulation resistance. Such testing is eff ective in mains with adjustable voltage in case of the change in the voltage polarity, which is typical of the adjustable gears of excavators and other mining machines. Based on the discussed approach, the insulation resistance control unit is designed to protect electrical equipment of main gear groups in mining excavators (mechanical shovels and draglines). The essential advantages of the control unit are the simple and reliable design, and the capacity to control the DC bus insulation resistance upon the change in the adjustable voltage polarity without additional sources of test signals.

1. Shkrabets F. P., Likarenko A. G., Pirozhenko A. V., Parkhomenko R. A., Petrichenko A. A. Mine vehicle of protecting from losses for the electric networks of 380 V of movable mountain machines of ore quarries. Elektromekhanіchnі і energozberіgayuchі sistemi. 2012. No. 2(18). pp. 85–90.
2. Martko E. O. Models of reliability and technical state of isolation of electric engines, used for the forecasting of their fail. Polzunovskiy vestnik. 2013. No. 4-2. pp. 138–142.
3. Cadick J., Capelli-Schellpfeffer M., Neitzel D. K., Winfield A. Electrical Safety Handbook. McGraw-Hill Companies. 4^th ed. New York : McGraw-Hill, 2012. 704 p.
4. Bise C. J. Modern American Coal Mining: Methods and Applications. Society for Mining, Metallurgy, and Exploration, 2013. 576 p.
5. PB 05-619-03. Safety rules during the open-cast mining of coal deposits. Iss. 3. Series 05. Regulations for safety, control and permitting activities in coal industry. Moscow : NTTs “Promyshlennaya bezopasnost”, 2004. 144 p.
6. Ivanov E. A., Kuznetsov S. E. Methods of control of isolation of ship electrical power systems. Saint Petersburg : Elmor, 1999. 80 p.
7. Olszowiec P. Insulation Measurement and Supervision in Live AC and DC Unearthed Systems. Heidelberg : Springer, 2013. 194 p.
8. Low Level Measurements Handbook. Precision DC Current, Voltage, and Resistance Measurements. 7th ed. Tektronix, 2016. 245 p.
9. Malafeev S. I., Malafeev S. S., Serebrennikov N. A. The Predicting Model for the Continuous Testing of the Dielectric Resistance and Protection of the Electrical Circuit. Kontrol. Diagnostika. 2012. No. 10. pp. 57–60.
10. Ivanov A. V., Rybakov L. M. Development monitoring of high voltage insulation electric equipment based on high sensing. Vestnik Chuvashskogo universiteta. 2015. No. 1. pp. 66–72.
11. Malafeev S. I., Anuchin A. V., Serebrennikov N. A. Excavator ЭШ-11/75 with New Control System of Drivers. Gornoe oborudovanie i elektromekhanika. 2013. No. 2. pp. 14–18.
12. Tulskiy V. N., Kartashev I. I., Kuznetsov N. M., Simutkin M. G., Nazirov Kh. B. The quality management of electric power in power grids. Gornyi Zhurnal. 2012. No. 12. pp. 52–55.
13. Malafeev S. I., Serebrennikov N. A., Anuchin A. V. Device for monitoring of insulation resistance in electric circuit of direct current. Patent RF, No. 2390033. Applied: 16.03.2009. Published: 20.05.2010. Bulletin No. 14.
14. Taylor J. R. An Introduction to Error Analysis. The Study of Uncertainties in Physical Measurements. 2nd ed. Sausalito : University Science Books, 1997. 344 p.
15. Resistors: reference book. Ed.: I. I. Chetvertkov, V. M. Terekhov. Second edition, revised and enlarged. Moscow : Radio i svyaz, 1991. 527 p.