Development and manufacturing of low-voltage
and high-voltage electric equipment

10 Chelyabinskaya Str., Ozersk, Chelyabinsk region, 456783, Russia
Phone: (35130) 4-36-40; fax: (35130) 4-87-15; e-mail:
Sales department. Phone: (35130) 4-82-45, 4-17-79; fax: (35130) 4-46-83; e-mail:

Карта сайта Русский язык

Low-voltage complete devices NKU-E98

JSC "Energoprom" produces and delivers all the product line of low-voltage complete devices of NKU-E98 series necessary for using at power stations, substations, enterprises for oil-fields construction, oil and gas production factories, metallurgical complexes, objects of housing and communal services. NKU, made according to Technical Conditions 3430-039-32574607-2002, are applied in alternating and direct current circuits of up to 1000 V.

Operating conditions

NKU are suitable for operation in stationary installations only, in industrial premises not containing caustic vapors and gases in concentrations causing metal and insulation destruction, besides NKU of open construction should be installed in premises without dust. The type of atmosphere is II in accordance with GOST 15150-69. Safety requirements are according to GOST‑75, GOST, GOST Р 51321.1-2000.

Height of installation above sea level in accordance with GOST 15150-69 is up to 1000 m.
Operating conditions group is М1, М6, М13, including operating conditions of seismic load at earthquake intensity of 8 points on МSК-64 scale.

Climatic modification and category of installation of NKU is in accordance with GOST 15150-69, intended for interstate deliveries and export to the countries with temperate climate - UHL4; to the countries with tropical climate - О4.

Modern polymeric powder covering used for painting metal jackets corresponds to resistance to influence of climatic factors combined under operating conditions UHL1.

As agreed with the customer, production of NKU of climatic modification and with a degree of protection different from the basic one is possible.


The embodiment of NKU can be in form of blocks, boxes, cases, panels and boards.
The way of service can be:
  • single-sided;
  • double-sided.

The design of each kind of NKU is executed as follows:
  • NKU-block in which apparatus and devices are installed on a frame, a plate or another basis no more than 1200 mm high. A degree of protection is IP00;
  • NKU-box is up to 1200 mm high, closed at all sides by the elements of the jacket, intended for hanging vertically (columns, walls, etc.). A degree of protection is IP31, IP41, IP54;
  • NKU-panel in which apparatus and devices are mounted on functional cabinets, a plate more than 1800 mm high. A degree of protection is IP00;
  • NKU-case is closed at all sides by the elements of the jacket in such a manner that, when doors, covers and other protected devices are closed, contacts with live parts are excluded. A degree of protection is IP20, IP31, IP41, IP54;
  • NKU-board consists of several panels or cases. A degree of protection is IP00 for open boards, IP20, IP31, IP41, IP54 - for protected boards;
  • NKU-benchboard is intended for control, signaling and  measuring equipment installation. There are modifications for standing and sitting operator work. A degree of protection is IP20, IP31.
Wiring inside NKU is made at the customer request in plastic punched buckets or in harnesses, laid and fixed on metalware details according to GOST 23586-96.

Dimensioning specifications of metal jackets of NKU cases and panels

Panels and cases NKU are intended for electric equipment, automatic and control devices installation.
Overall dimensions of cases and panels are given in table 1.1 and shown in figure 1.1


The degree of protection of metal jacket is in a range from IP00 up to IP54.

A casing of metal jacket that is a welded metal cage with punching and demountable elements is shown in figures 1.2,1.3

Cases and panels are one-door at NKU width up to 800 mm; two-door - at NKU width more than 800 mm.
NKU specification is made on the basis of the customer documentation or standard projects.


NKU-boxes and -boards

They are intended for electric equipment, automatic and control devices installation.

Overall dimensions are given in table 1.2 and shown in figure 1.4.

NKU-boxes and -boards are of single-sided service, hinged, built-in or floor modifications only.

A casing of metal jacket is a welded metal structure with demountable top and bottom covers (modification IP21, IP31), with welded top and bottom covers with semi perforated holes for gaskets (modification IP54).

Wiring inside NKU is done in harnesses.

NKU-boxes and -boards are completed by the equipment on the basis of standard projects or customer documentation.


Input NKU with automatic standby activation (PVA, PVAIM panels)



They are intended for completing distribution electrical boards and electrical drives control boards up to 1000V in networks with dead-earthed neutral which have two sections of collecting buses divided by a section switch. Thus two variants of collecting buses supply are provided.

The first variant is a two-input supply. Each section of buses is supplied by its working input. The first input is a reserve one for the second input and vice versa.

The second variant is a three-input supply. It is similar to the first one, but provides an additional reserve input for one of the sections from diesel power station (DPS). It is energized in case of simultaneous disconnection of the two inputs.

Engineering data

For the boards of PVA panels of PVAM2, PVAM3 series albums of electric circuits for the currents from 100 A up to 1600 A are developed.

For the boards of PVA panels of PVAIM2, PVAIM3 series albums of electric circuits for the currents from 100 A up to 3000 A are developed. Significant advantages of the given devices are operating speed, reliability and compactness of the equipment.

Design and action

Structurally boards of PVA panels are made for single-sided and double-sided service with top and bottom power supply lines. For top power supply to panels, boards or cases constructive demountable elements in the form of bus bar bridges, buckets or trays fasten on the top panel socle are provided.

In PVAM, PVAIM boards entry and section switches are installed in separate panels. The general view of the board with panels of different versions is shown in figures 1.5, 1.6, 1.7.
Distinctive features of the given series of devices are:
  • overall dimensions of the panels are the same for currents up to 1600 A;
  • it is possible to record electric power on any types of meters;
  • application of stick-in automatic switches is possible. When stationary switches are applied, circuit breakers are installed in case the former are to be repaired;
  • automatic standby activation  (ASA) circuit provides two operating modes: manual and automatic;
  • voltage control at inputs;
  • control circuits protection against sort circuit;
  • reset of a normal mode;
  • the relay part of the control circuit can be made on the base of both electrical mechanical relays, and intellectual Zelio relay of  "Schneider Electric" production. Microprocessors of BMRZ, BMPA blocks are produced by the scientific and technological centre "Mehanotronika"Ltd; application of microprocessor blocks of other manufacturers is possible.

Variants of circuit decisions

The relay part of the control circuit can be executed on the base of:
  • electromechanical relays;
  • intellectual Zelio relay of  “Schneider Electric” manufacture;
  • BMRZ, BMPA microprocessor blocks of the scientific and technological centre "Mehanotronika"Ltd;
When realizing the circuit decision on the basis of electromechanical relays in PVA panels, we provide for:
  • pointer-and-scale instruments of current and voltage control;
  • signal system of input and section switches condition (on - off) on light-emitting diodes.
Use of Zelio relay allows:
  • to increase the board reliability;
  • to simplify ASA realization;
  • to reprogram the circuit on the controller itself;
  • for PVAM2 (3-1000 (1600) boards - to reduce the number of panels (the relay case is removed);
  • to reduce time for service and simplify operation;
  • the total cost of board remains the same, but the pay-back period is considerably reduced due to lower maintenance charges since  it isn’t necessary to adjust and clean the relay, the nomenclature and the size of a spare parts set decrease.
One of the variants of ASA circuit arrangement is on the basis of BMRZ-0,4 and BMPA microprocessor blocks of "Mehanotronika" Ltd. These blocks are included in the automatic control system through RS-458 standard. Connection by consecutive channels is carried out according to MODBUS protocol. The given system decision can be applied on objects with both direct, and alternating operative current. Application of ASA circuit on the given blocks provides high accuracy of measurements and constant characteristics that allows to increase sensitivity and speed of protection essentially.

Additional functions of the controller:
  • storage of protection and automatics setting parameters during all service life, irrespective of supply voltage availability, and their fast changeover;
  • continuous self-diagnostics during all period of work;
  • account of time and number of failures;
  • account of the number of on-off cycles;
  • possibility of setting a desirable working algorithm;
  • possibility of connecting to the automatic control system and remote control from a remote computer.

NKU of outgoing lines

They are intended for distribution of electric power from main buses to outgoing feeder cables, for asynchronous motors control.

They are completed with typical electrical energy distribution blocks and control blocks.

In typical control blocks, as a rule, the following kinds of protection are provided:
  • power circuit protection against short circuits and overloads;
  • engine protection against overload;
  • protection of the engine against breakage of phases;
  • control circuits protection against short circuits.
This NKU type includes control blocks with microprocessor protection and engine control devices (EPCD) with automatics of events, current parameter and voltage registration.

EPCD combines the functions of maximal and minimal current relays, thermal relay and built-in thermal protection.

Due to application of control blocks with EPCD, the following additional functions are provided:
  • protection against current unbalance;
  • protection against starter windings overheating;
  • protection against reduction of engine insulation resistance (phase - case);
  • alarm signaling activation in case of failure;
  • remote engine start, settings change, engine characteristics control, reading of failures list through RS 485 interface ;
The structure of NKU of outgoing lines can include blocks of free design made in accordance with the technical documentation given by the Customer.

NKU of outgoing lines are manufactured using domestic and import component parts and materials, in particular, “Schneider Electric”.

Application of import control and distribution blocks allows to reduce NKU dimensions essentially and also to increase reliability and serviceability of the product.

Busbar bridges

At two and multi-row arrangement of NKU-cases busbar bridge (BB) is installed between the rows in a premise.

A busbar bridge represents a metalware, installed in closed buckets, painted in the same color as all NKU-cases.
Insulators and buses are set in the buckets. In BB an access to electric equipment by means of demountable covers and buckets, allowing service without dismantling, is BB structure is made on the basis of a technical project of the Customer (according to applied questionnaire).

NKU of free design

They are intended for realization of atypical electric circuits and individual requirements of the Customer.

NKU of free design can include the following equipment:
  • automatic devices;
  • relay protections;
  • condenser installations;
  • control and measuring devices;
  • other equipment at the request of the Customer;

Order formulation

When ordering control NKU, it is necessary to specify:
  • typical NKU designation  (a box, a panel, a case);
  • overall dimensions;
  • rated voltage of all NKU circuits;
  • nominal operating currents of corresponding circuits under NKU specifications;
  • a kind of climatic modification and a rate of IP.
When ordering typical devices, it is necessary to specify NKU designation, modification, circuit number, rated voltage and current of the device, rated currents of outgoing group lines, input switch and input clips arrangement (top or bottom).

  1. At the absence of full specifications in the order formulation the company chooses NKU type on its own.
  2. It is possible to produce NKU-E98 of various functional purposes with metal jackets of foreign manufacturers: Rittal, Sarel, Prizma.
To attention of the customers!
Besides the complete typical devices included in the catalogue, JSC "Energoprom" takes individual orders for manufacturing of complete devices (blocks, panels, boards, cases, boxes, benchboards, NKU).


Смотрите также >     Блок-бокс типа БНКУ-Э Смотрите также >     Блок-боксы типа 2БКТП-Э с КТПВ и НКУ
Have you got any questions? Call or come to us. Highly qualified
skilled consultants will help you to find optimal
decision for your business!
10 Chelyabinskaya Str., Ozersk, Chelyabinsk region, 456783, Russia
Phone: (35130) 4-36-40; fax: (35130) 4-87-15,
e-mail:, site:,