Nexus switchgear

Nexus switchgear chambers are intended for operation in electric installations of a three-phase alternating current with frequency of 50 and 60 Hz and voltage of 35 kV for system with the neutral isolated via arc suppression coil. Used to organize power supply to various consumers of the oil and gas industry, railway facilities, industrial enterprises, agricultural facilities, as well as cottage settlements and individual dwellings zones.

The Nexus switchgear cell is a prefabricated metal structure, the components of which are connected to each other with rivets. All metal parts of the cell housing are made of a bent profile made of at least 2 mm thick sheet. Devices and fittings of the main and auxiliary circuits are located inside the housing. Cell maintenance conditions are one-way and two-way.

For safe maintenance and fault location, the housing is divided into isolated sections.

The cell consists of five sections:

• cable connection section;
• secondary distribution section;
• draw-out element section;
• cable inlet section
• busbar section.

From the front side, access to the section is restricted by specially designed doors.

Cable connection section and cable inlet section

The cable connection section consists of:

• earthing device with manual or electric motor drive (optional);
• current transformers;
• zero sequence current transformers (for two-way cell service type);
• non-linear surge suppressors;
• support insulators and insulators with voltage dividers;
• cable glands with power cable clamps (for two-way cell service type);
• cable distribution heads (for two-way cell service type);
• excess pressure relief valve with end switch;
• optical arc protection sensor (optional);
• anti-condensation heating element (optional);
• ground bus system;
• metal channels for auxiliary circuits;
• busbar temperature monitoring sensor (optional).

The compartment is designed for both bus connection (side, top) and single-phase or three-phase high voltage power cables. An earth electrode with an instantaneous operation mechanism is used In Nexus switchgear cabinets, which does not depend on the control shaft rotation speed.

The location of the earthing device eliminates the possibility of the earthing blades falling on live elements and allows visual control of the earthing blades position through an inspection window on removable panels or the doors of the cable connection section. The earthing device drive is located on the right wall of the draw-out element section.

Secondary distribution section

Dimensions of the secondary distribution section compartment (width 1,200 mm) allow to apply various digital devices of relay protection, control and automatics, devices of control and account of electric power, digital converters, fiber optic devices of arc protection, terminal rows and other equipment of secondary switching circuits.

The following is installed on the section door:

• control keys;
• malfunction signal and protection triggering lamps;
• electrical measuring devices;
• indication and control units for microprocessor-based relay protection devices.

Relays, terminal connections, circuit breakers, low voltage fuses and other devices are mounted on DIN rails, making it easy to install and replace these elements.

The elements of low-voltage equipment are interconnected by multi-core wires (harnesses) laid in a protective box of intersection connections located directly on the module roof.

For protection against external influences, an anti-condensation heating element with automatic control from the thermostat is installed in the section.

For ease of maintenance, the section is equipped with LED lighting.

Withdrawable element compartment

Withdrawable element compartment of the Nexus switchgear cabinet consists of:

• draw-out element with manual (electric motor) drive;
• arc-proof door with multi-point lock;
• a system of movable metal shutters which automatically close when the draw-out element is moved out of the operating position;
• removable metal partitions allowing access to the busbar section and the top of the connection compartment;
• lead-in insulators of the contact unit with fixed contacts;
• a system of mechanical and electromagnetic interlocks for the draw-out element movement;
• earthing device and door opening interlock from the position of the draw-out element;
• excess pressure relief valve;
• plug connector for the auxiliary circuits of the draw-out element;
• light bulbs.

Draw-out element with circuit breakers, disconnectors or voltage transformers allows easy maintenance and repair of this equipment during operation.

The draw-out element relative to the housing of the Nexus switchgear cabinet can take the following fixed positions:

• operating: all main and auxiliary circuits of the cabinet are closed;
• control: main cabinet circuits are open, auxiliary circuits are closed, the draw-out element remains in the cabinet, the door is closed;
• repair: main and auxiliary circuits are open, the draw-out element is outside the enclosure.

The draw-out element is brought out into the repair position using a special ramp.

The auxiliary circuits of the draw-out element are plugged into the plug connector.

The shutter lifting system in the draw-out element section of the Nexus switchgear cabinet allows to move the shutters away from the lead-in insulators of the contact unit, and therefore from the main contacts of the switch. The shutters move along curved guides, the top shutter moves up, the bottom shutter moves down. No need for additional contact insulation.

The design of the curtain mechanism includes eyelets for locking of top shutters by the hinged lock with possibility of opening of bottom shutters during the planned inspections and repairs in high-voltage sections without putting the whole section into repair. Busbar section The busbar section includes: - copper flat current carrying buses; - lead-in insulators of the contact unit; • lead-in and dead end busbar insulators with panels made of non-magnetic materials; - excess pressure relief valve; - optical arc protection sensor. Nexus switchgear busbars are made of copper profile and marked in accordance with the assembly drawing included in the working documentation for the switchgear.