Overview

The HXGN15-12(SF6) type unit-type AC metal-enclosed ring main unit (hereinafter referred to as ring main unit) is a new generation of high-voltage electrical products independently designed and developed by our company based on the introduction of advanced foreign technology and in accordance with the requirements of domestic rural power grid and urban power grid transformation. All technical performance indicators meet the IEC62271-200:2003 and GB3906 standards.

The main switch, operating mechanism, and components of the ring main unit use original ABB parts or domestically assembled SFL-12/24 type switchgear using imported components. Original ABB HAD/US type SF6 circuit breakers or VD4-S type vacuum circuit breakers can also be installed according to user needs. It has two operating modes: manual and electric.

The cabinet is machined and riveted using CNC machine tools, achieving an IP3X protection rating and featuring reliable mechanical interlocking and anti-misoperation functions. This product boasts significant advantages such as small size, light weight, attractive appearance, easy operation, long lifespan, high parameters, no pollution, and minimal maintenance. The HXGN15-12(SF6) type unit-type AC metal-enclosed ring network switchgear is suitable for receiving and distributing electrical energy in 50Hz, 12kV AC power networks. The main switch inside the cabinet is an SF6 switch.

Model and Meaning

Normal usage conditions

Ambient temperature: Upper limit +40℃, Lower limit -25℃

Altitude: Not exceeding 2000m;

Relative humidity: daily average not exceeding 95%; monthly average not exceeding 90%;

Surrounding environment: The surrounding air is not significantly polluted by corrosive or Flammable gases, water vapor, etc.

There is no frequent, violent vibration.

Main technical parameters

Structural characteristics

Cabinet structure

The ring main unit is constructed from 2mm thick aluminum-zinc coated sheet (or cold-rolled sheet with powder coating) riveted together. Two pressure relief ports are located at the rear of the unit: one for the cable compartment and the other for the load switch/busbar compartment. This structure maximizes the reliability of personnel during installation and equipment operation.

Each compartment

Busbar compartment

The busbar compartment is located at the top of the cabinet and connects to the adjacent switch cabinet.

The load switch is an independent unit, filled with SF6 gas.

Cable room

Approximately 75% of the space is used for cable connections, fuses, grounding switches, and CT/PT installations.

Institutional compartments and interlocks

The small compartment includes the operating mechanism and mechanism interlocks, as well as position indicators, auxiliary contacts, trip coils, live indicators, and interlocks.

Relay box

The relay box, located at the top of the cabinet, is optional. Small compartments are used to install special devices such as instruments, relays, and motor units. (Circuit breaker compartment)

A circuit breaker (SF6 or vacuum) can be placed below a load switch.

External dimensions (mm)

Basic components

SFL type load switch (ABB genuine part)

The SFL type load switch is a double-break, rotary moving contact type that uses SF6 gas as the arc-extinguishing medium. The moving and stationary contacts are housed in a reinforced molded epoxy resin shell. At the operating shaft lead-out end is a transparent, thermoformed plastic end cap, through which the status can be observed.

Each switch is permanently sealed after being filled with 1.4 bar of SF6 gas (SFL stands for "Permanently Sealed"), and any gas leakage can be detected using an ammonia detector. The switches can be installed vertically or horizontally. In unitized cabinets, a typical installation method is horizontal mounting with a steel partition between the cable compartment and the busbar compartment. This installation method encloses the switch housing within a grounded steel plate and isolates the busbars from the cable joints to meet the most stringent safety requirements for operation and maintenance.

If an internal arc occurs, there is a structural weak point at the rear of the outer casing. This weak point will be breached, allowing the arc gas to escape from the switch. Subsequently, the arc relief valve on top of the cabinet will be breached, guiding the overpressure gas out of the cabinet.

Optional equipment includes 2 normally closed and 2 normally open auxiliary contacts, plus 2 normally open and 2 normally closed extension contacts, and a shunt trip coil supplying the SFL of mechanism A.

The switch for the K-selector mechanism is SFL12/17.5 IVDP575305RI.

SFL24K IVDP575304RI

Select switch SFL12/17.5 IVDP575303RI for mechanism A.

SFL24A IVDP575302RI

VD4-S Vacuum Circuit Breaker (ABB Genuine Part)

The VD4-S type vacuum circuit breaker is designed specifically for unit switch cabinets. Its breaking capacity is sufficient to handle various conditions, including normal switching of equipment or branch network operations, as well as short circuit breaking under special circumstances.

Vacuum circuit breakers are particularly suitable for networks that operate frequently within their operating current range. The VD4-S vacuum circuit breaker is equipped with a spring-operated mechanism that features reclosing capability (open - 0.3S - close - open - 180S - close - open), and offers reliable operation and a long service life. The entire circuit breaker consists of three vacuum switching bulbs encased in a resin-insulated cylinder and has a vertical structure.

The arc is extinguished by the helical grooves of the arc-extinguishing contact, which forcefully displace the arc. Because the minimum static vacuum level inside the switch insulation cylinder is 10⁻⁴ to 10⁻⁸ bar, a very high insulation strength can be achieved despite the relatively small gap between the switch contacts. The arc extinguishes at the first zero point of the short-circuit current.

Because of the small contact gap, the high conductivity of the metal gas plasma region at the arc voltage drop, coupled with the short arcing time, results in extremely low arc energy. This is beneficial for extending the lifespan of the contacts and even the entire switch.

Standard equipment:

Manual operation

Electric operation

Auxiliary contact 2 Normally open 2 Normally closed

Shunt trip with position contact

Shunt closing coil

Optional equipment - S5 or PR512 overcurrent relay:

Low voltage trip unit

Interlocking coil

Circuit breaker model:

VD4 1206-20S

VD4 1706

VD4 2406

HAD/US type SF6 circuit breaker (ABB original part)

The HAD/US type SF6 circuit breaker is specifically designed for ring network switchgear. Its breaking capacity is sufficient to handle various conditions, including normal equipment switching or branch network operation, as well as short circuit breaking under special circumstances. The new generation HAD features the latest SF6 breaking technology, coupled with a simple structure requiring very little operating energy. This simple energy storage operating mechanism has a long mechanical life during use, and the circuit breaker uses a spring operating mechanism to achieve automatic reclosing operation.

The special structure of the switch's breaking section ensures an exceptionally long electrical lifespan. The switch is designed as a separate, independent column structure, vertically mounted. It employs a self-extinguishing arc principle, using the energy of the electric arc itself to extinguish it. When the circuit breaker trips, an arc is generated between the moving and stationary contacts within the arc-extinguishing chamber. The high temperature and ionization effect of the arc cause the SF6 gas pressure to rise rapidly within the chamber. As the pressure increases and the contacts gradually separate, the gas is forcibly ejected through nozzles to the outside of the arc-extinguishing chamber, thus thinning, cooling, and extinguishing the arc, preventing reignition. Therefore, the switch's moving parts require very little energy, further enhancing long-term operational reliability.