World-Class Remote Backup Protection for 0.4 kV Electrical Grids are Made in Russia

The 0.4 kV networks have been the most damageable and the least protected in all areas of power engineering and industry, including the oil and gas industry.

Short circuit currents in 0.4 kV networks as compared to 6 to 10 kV networks heavily depend on transition resistance in the short circuit point, including the electric arc parameters.  Short-circuit current drops noticeably with the distance from the 0.4kV integrated transformer substation (ITS). The currently operated ITS's - the KTP-6(10)/0.4 kV model equipped with a circuit breaker and protection devices cannot provide the required number of relaying functions (like sensitivity, fast response, performance stability, detuning from the group execution mode and self-starting of motors, etc.).

In cases of cabling short circuits followed by protection/shutoff device failure, cable damage by large ignites and cabling fire ensues. Lack of efficient protection results in a mass-scale failure (burnout) of circuit breakers at the input terminals and outgoing feeders of 0.4 kV services feeding the submersible pumps installed at the oil production facilities.

Standard overcurrent protection cannot provide backup of protection devices and outgoing feeder breakers. It must be tuned away (desensitized) from the motors startup/self-start currents.

The problems with 0.4kV networks can be addressed through long-range backup protection systems and higher overcurrent protection sensitivity. The authors of long-range algorithms are the Russian scientists A.V. Belayev and M.A. Edlin.
These unique protection capabilities unparalleled in world practice have been implemented in the BMPZ-0,4 terminals that are manufactured by Mekhanotronika Research and Development Center.

The philosophy behind the new protection devices is based on the continuous analysis of current network parameters and calculation of criteria to be used for clear identification of short circuit occurrence in the 0.4 KV networks with identification of the motor start/self-start modes.

Emergency parameters in the long-range backup algorithms during short circuit and configuration of overcurrent protection interlocks during motor starts and self-starts are the correlations between the increments of active and reactive components of positive-sequence current. This protection reliably functions with static (idle) load as well.

The BMRZ-0,4 terminals, complete with the BMPA emergency control scheme unit, use complex algorithms for the automatic throw-over circuit-breaker in the КТP-6(10)/0.4 kV with two to four 0.4kV inputs and busbar sectionalizing switch installed between the two busbar sections.  

The standard mode scheme can be automatically restored after enabling the automatic throw-over circuit-breaker.

Apart from original relay protection functions, the BMPZ-0.4 terminals provide current zero-phase-sequence protection, local and remote breaker control, registration of emergency events and oscillographs, and measurements of standard-mode electrical parameters, as well as interfacing with PC and SCADA.
The BMPZ-0,4 terminals have been produced in lots since 2000. Top building companies in Russia and Belarus buy them to equip their KTP-6(10)/0.4 substations for switch- and control gear.

Integrated transformer substations have been used at various facilities operated by Gazprom, AK Transneft, and Severstal plants, as well as various power stations and manufacturing enterprises. Gazprom specialists expressed their appreciation of the unique performance characteristics of the BMPZ-0,4.
The unique functions of long-range backup of protection and breaker failures and interlocking protection current during motor start and self-start implemented in the BMPZ-0,4 terminals have proven their high performance with six years of smooth operation of over 1,000 relay protection items manufactured by Mekhanotronika for the facilities in the oil and gas industry, manufacturing enterprises and traditional power engineering.

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