JSC Nevsky zavod Electroshchit produces individually-designed block-module double-transformer step-up and step-down complete substations (KTP) with capacity up to 3150 kilowatts, factory-assembled. Step-down KTP are intended for: receiving of electric power of the three-phase current with frequency of 50 Hz at the voltage of 6(10) kV and for its transformation into electric power with 0.4 kV voltage; power distributing and accounting; reactive power compensation; overload and fault protection of busbars and outgoing lines. Step-up KTP are intended for: operation as a part of autonomous power systems; high-voltage consumers power supply from low-voltage diesel or gas engine power stations. Structure of conventional signs is given in attachment A.

Structurally KTP is a three-sectioned block module, in which equipment of high-voltage lead-in and low-voltage switchgear are placed in the central section, and power transformers - in the side sections. The sections are isolated from each other and equipped with the door and the swinging gate. The transformer sections are of cold fulfillment, the central section of isothermal (heated) fulfillment. The transformer sections have side blind. If the oil transformers are used, there is an oil collector in the section foundation. The oil collector is counted on the full capacity of the transformer oil. The oil collector is rigged with drain hole and plug. For easy mounting and demounting of power transformer, the special facility is provided. This facility corresponds to the metal construction with the winch and rails that are used to roll the transformer in and out of the section.

High-voltage (6,10 kV) lead-in (lead-out) equipment are designed on the basis of KSO chambers of Rial type, own production. The application of gas-insulated switchgears, vacuum circuit breakers is the distinctive feature of these chambers, as well as inside sectioning of the chambers and their small dimensions and block system, that excepts the staff incorrect operations. These chambers are adjustable and service-strong. Also the application of RM6 monoblock (Schneider Electric) as a high-voltage lead-in (out) is possible on the customers request .

KTP technical features

Parameter designation


Power transformers capability, kVA (oil-immersed)


Power transformers capability, kVA (dry-type)


Rated voltage of the primary winding, kV

0.4, 6, 6.3, 10

Rated voltage of the secondary winding, kV

0.4, 6, 6.3, 10

Short-time withstand current (HV/LV) during 1 s, kA


Peak withstand current (HV/LV), kA


Insulation level acc. to GOST 1516.3-96


Neutral mode

Dead-grounded, insulated

KTP are designed for operation in the following climate conditions:

-operational ambient air temperature: from -60 0C till +40 0C;

-relative humidity: up to 80% (t = +200C);

-environment industrial atmosphere, type 2 according to GOST 15150-69;

-altitude above sea level: up to 1000 m;

-substations can be step-down or step-up type (power supply from generators 0.4 kV).

KTP equipment

KTP are equipped with power transformers, produced by Minsk electrotechnical plant named after V.I. Kozlov. Transformers of another manufacturer may be installed on the customers request.

The connection of the transformer and the switchgear (0.4 kV), that is situated in the heated chamber, is provided with the help of busline with copper and aluminum bas bars. The bus bars are connected to the transformer through bus compensators.

Sometimes the installation of high-voltage switchgear in KTP is necessary, for example: to protect the transformers; to sectionalize it with or without reserve switching device; for double-ended substation. In that case KTP is equipped with KSO Rial chambers, produced by JSC Nevsky zavod Electroshchit.

The leads-in of low-voltage switchgear are equipped with draw-out automatic breakers. The outgoing lines protection is provided with stationary or plug-in automatic breakers, as well as with fuse-disconnectors. Reserve switching device (AVR) is provided with sectionalizing draw-out breaker and programmable controller. Its also possible to output control signals to the control console. Switching devices may be of home or foreign manufacture, it depends on the customer requirements.

Reactive power compensator in KTP

The technical information is applied to the reactive power compensators, intended for reactive power generation in low-voltage three-phase distribution power systems of industrial enterprises and other objects of national economy to save energy.

Reactive power compensators can be:




Nonadjustable reactive power compensators are designed for raising power coefficient (cos φ) of industrial electrical installations and in low- voltage distribution systems with the constant reactive power consumption.

Adjustable reactive power compensators are designed for keeping power coefficient (cos φ) invariable in industrial electrical installations and in low- voltage distribution systems with the constant reactive power consumption. Adjustable reactive power compensators provide set value of cos φ during maximum and minimum load hours, as well as they except over-generation of reactive power in line of power source.

Compound reactive power compensators are designed for keeping power coefficient (cos φ) invariable in three-phase low- voltage distribution systems and other objects with reactive power consumption, that includes constant and variable components.

For three-phase distribution systems and other low-voltage objects with large number of nonlinear load, that generate high harmonics (over 13%), filter compensation devices are manufactured.

Fast-acting compensation devices are designed for three-phase distribution systems and other objects with fluctuating load (welding apparatus, electric arc furnaces).

Reactive power compensators are used for reactive power compensation in group power systems of industrial plants and separate collectors.

Reactive power compensation devices may be available with KTP and may be placed inside of low-voltage switchgear chambers.