Following the development of power industry, compact switchgear equipment will be the future trend and this is also the requirements from most of our environmental concern end user customers. The using of compact switchgear equipment will reduce the occupancy of floor space and lower the civil construction cost, we can also reduce the consumption and discharge of the SF6 gas (a greenhouse gas), compact switchgear will meet the nowadays environmental requirements. With our long years of experience in high voltage switchgear equipment design, and adopting the latest switching device design philosophy, our company has developed a new generation of hybrid gas insulated switchgear type ZHW12-40.5.

This Hybrid GIS switchgear equipment is having a very compact design, therefore, it is very suitable for urban and suburban substations installations and also the best choice for retrofit substation projects. This product is ready for 40.5kV digital substation and smart grid applications.

Note: * For high altitude applications exceeding 1000m above sea level, please inform the manufacturer in order to allow us to take necessary measures in reinforcing the insulation level; **For low ambient temperature applications below -40℃, it is required to take special measures to prevent the liquefaction of SF6 gas.

1.Compact design, require less floor space

By optimizing the Electric Field distribution of each and every component of the product and without scarifying the product reliability, we have designed the most compact HGIS. The floor area required for installing this product is only 2.5m×2.0m (length ×width), which can be considered as the smallest available from the market place. Thanks to the compact design, the end user customer can save a lot of floor space and lower their civil construction cost.

2.Excellent breaking performance

The latest generation of self blast arc extinguishing philosophy and with the optimized design of the electric field and gas flow field contributed to the excellent breaking performance of the circuit breaker, and good making and breaking capacity for different short circuit or fault current (including out-of-phase earthing) and low current (including line charging current); the using of new material type make the nozzle more burning-resistant, therefore, the electrical life of the circuit breaker can highly be increased.

3.High insulation level

We have optimized the electric field distribution of each and every insulation component. This product is designed to meet the highest insulation requirement of 40.5kV power equipment, and we have allowed for very high safety margin in the design. This product can reach a power frequency withstanding voltage up to 110kV, and lightning impulse withstanding voltage up to 215kV. Our key components, to a very high extend are supplied from famous multinational suppliers.

4.Aluminum enclosure, low loss, light weight, highly corrosion resistance, simple foundation requirements, easy to transport, quick and easy erection and commissioning activities.

5.Intelligent secondary control and monitoring

The secondary control part of this product has adopted the intelligent control and sensing technology that fit for the latest digital substation design. Meanwhile, traditional secondary control scheme is also available according to customer requirements.

Construction and operating principle of the product

ZHW12-40.5 Hybrid GIS switchgears are configured from different standard functional modules, namely, Circuit Breaker GCB (Single or Double Busbar), Combined Diconnector/Earthing Switch TPS, Potential Transformer PT, Current Transformer CT, etc. These modules are with a common connection design, all connecting flanges are with the same dimensions and connection holes, therefore, different functional modules can be connected and configured according to different substation design and layouts.

1. Circuit-breaker

The circuit-breaker of ZHW12-40.5 Hybrid GIS Switchgear use SF6 gas as its arc extinguishing and insulating media.

The construction of the circuit-breaker is of three-phase aluminum alloy tank type, and is designed for outdoor application. It has a three-phase mechanical connection through a driving device. The linked three phases are operated by the spring operated driving mechanism CT10-A installed at the center and mounted on the same frame, with unique and delicate appearance. The driving mechanism output crank is connected to the circuit breaker through the pushing rod and transmission shaft. Gas is connected through the pipelines. The circuit-breaker consists of enclosure, arc extinguishing chamber, driving unit, crossbeam, driving mechanism, steel supporting structure and secondary control circuit, etc.

Each phase is an independent tank, connected by pipelines, SF6 gas is used as the insulating and arc extinguishing media. The SF6 gas in the three phases of the circuit-breaker is connected during normal operating, its pressure and density is being monitored by a pointer type density meter. Since mixed pressure arc extinguishing principle is used, and we have optimized the circuit breaker moving parts design, therefore we have improved the efficiency of the driving mechanism and lower the mechanical force required for the circuit breaker operation.

This circuit-breaker is equipped with a gas density meter with electrical contacts. The gas density meter has a temperature compensation system to reflect the gas pressure at 20℃, false alarm will not be given from the meter when the SF6 gas pressure change is caused by the change in gas temperature. The meter will only send out alarm or blocking signal when SF6 gas leakage occurs. When the SF6 gas pressure descends to 0.45MPa, the controller will send out a gas pressure low alarm signal, when the pressure further descends to 0.40Mpa, blocking signal is sent out and circuit-breaker operation is prohibited.

1.1 Operating principle

The operating principle of the circuit-breaker is based on arc extinguishing mechanism: namely using the pressure difference generated from the heat of the arc to drive the SF6 gas to flow, so as to extinguish the arcing. The mechanical force required for the closing and opening of the circuit-breaker is delivered from the closing and opening spring within the driving mechanism.

1.2 Principle of arc extinguishing

The arc extinguishing chamber of circuit-breaker is of mixed-pressure structure. The breaker is inflated with gas with rated pressure. During breaker open, the movable cylinder moves relatively to the standstill moving contact to compress the gas inside the cylinder, at the same time, high pressure generated from the arcing is transmitted into the cylinder and highly increase the gas pressure within the cylinder, a very high pressure difference is formed between the outside part of the cylinder. When the arcing contact is pulled out of the nozzle, SF6 gas with very high pressure will blow the arc hardly through the nozzle, and forces the arc to extinguish at current zero. The pressure difference vanishes as soon as the breaking action has completed then the pressure balance between the pressures inside and outside cylinder is recovered. There is a check valve is mounted on the moving contact stand, and the gas pressure is very low during breaker closing.

1.3 Construction of the CT10-A spring operating driving mechanism

CT10-A spring adopts a clamp structure, and is mainly composed of driving unit, spring charging unit and releasing unit. The driving unit, located between the right-side wall and the centre partition, is of cam linkage structure, two quadrants are arranged on the two sides of cam separately, so as to achieve steady and reasonable stress, as well as stable and reliable operation. The spring charging unit is located between the left side wall and the centre partition, with closing spring arranged outside both sides of the mechanism. Opening coil is located under the outer side of the right side wall, limit switch is located above the outer side of the left and right side walls, closing magnet is located at the bottom right side of centre partition, spring charging motor and auxiliary contacts are arranged under the mechanism, “closing” and “opening” push buttons are located on the both sides of right-side wall and centre partition above the front side of the mechanism, spring charging indicator and “closing” and “opening” indicators are also arranged on the front side of the mechanism. The mechanism is mounted on the circuit-breaker with M12 bolts through the mounting holes on two angle steels fixed on the right side wall and centre partition.

2.Combined disconnector/earthing switch

Combined Disconnector/Earthing switch can be fitted on the busbar side or on the feeder side of the ZHW12-40.5 Hybrid GIS switchgear, this Combined Disconnector/Earthing switch is a three-position switch, installed inside the spherical metal tank of the switchgear itself. The motor driven driving mechanism is installed at the end of one of the phase, and through the driving rod which operates the three-position switch. Addition Combined Disconnector/Earthing switch can be fitted into the HGIS Hybrid Switchgear, for internal (bus coupler) or external (incomer/feeder isolation) applications.

Busbar connected/Disconnected/Earthing connected can be realized by the turning of the moving contact of the three-position switch at different angles.

2.1 Construction and operating principle of the operating mechanism of the combined disconnector/earthing switch

2.1.1 Introduction
OA-15 motor driven driving mechanism is used for opeating the disconnector/earthing switch, by turning the moving contacts of the three-postion switch clockwise or anti-clockwise at a certain angles, the closing, opening and earthing connection of feeder can be realized. The disconnector/earthing switch may, and can also be operated manually by means of a crank when it is really necessary.

2.1.2 Electrical operation and interlocking
OA-15 motor driven driving mechanism can be operated "Local" on site or by "Remote". This can be selected through the "Selector" switch.

With the electrical interlock of control circuit, the operation of isolating/earthing switch is permitted only when 1. the Circuit Breaker is at "Opening position" and 2. pressure of the SF6 gas is higher than the "locking pressure". Moreover, other interlocking conditions can be added between the "external blocking terminals" of control circuit according to the end user requirements. For the earthing switch on the line side, in addition to the above interlocking conditions, external interlock can be realized by line PT secondary voltage or other conditions as well.

3.Porcelain bushing

Porcelain bushing, featured by high strength and excellent air tightness, is a supporting and insulating component for the connection between circuit-breaker main circuit and power system, and it is also a pressure container.

4.Current transformer

ZHW12-40.5 switchgear is designed to use ring type current transformer which is installed outside the gas chamber and can be replaced from the outside without disassembling gas chamber. The primary circuit is the conducting rod in the composite insulating bush or porcelain bushing. Generally, the current transformer is installed under the bushing on the line side. In case of special requirements, it can also be installed on the busbar side or on both sides; such requirement should be specified in the order. For double busbar panels, it is usually installed on the line side only. Limited by the height of installation, up to 4 iron cores are permitted on each side of each phase. For moderate precision and load requirements, up to 5-6 iron cores are allowed.

5.Potential transformer

The switchgear can adopt EVT (electronic voltage transformer) to detect the primary voltage through capacitive voltage divider or resistance voltage divider. The voltage sensor doesn’t have any iron core, so it is small in size, light weight, high precision, wide frequency range, wide measuring range, and good linearity. It has simple structure and mature technology, thus can meet the requirements of modern power system on compacity, digitization and intelligentization, as well as on measuring, protection and transient protection, and is a perfect component for constructing modern digital substation.

This equipment can also adopt OVT (optical voltage transformer), the principle of system of which is as follows:

6.Surge arrester

The core elements of the surge arrester are the zinc oxide disks which are connected in series inside the surge arrester. The inner part use silicon rubber that has excellent dielectric property as main insulating material. The external connecting part has good and it is plugged into the switchgear in a tightly-fitted way, so as to ensure good electrical connection between the surge arrester and the switchgear. A pressure relief device is available to prevent the surge arrester from explosion, under abnormal conditions. Earthing and fastening thread holes are available at the connecting flange of the surge arrester for earthing connection and fixing.

Key technical data of the product

Technical data of the circuit breaker of ZHW12-40.5

Technical data of the spring charging motor of the circuit breaker

Technical data of the closing coil

Technical data of the opening coil

Key data of the disconnector switch and the earthing switch

Key technical data of the product

Technical data of the motor operated driving mechanism of the combined disconnector/earthing switch Front-end three-position isolating switch

Back-end three-position isolating switch

Auxiliary contacts: 10 pairs of normal-open contacts, 10 pairs of normal close contacts, continuous current allowed for the contacts should be not lower than 10A.
Travel switch: 1-4 pairs of normal-open and normal-close contacts are available, continuous current allowed for the contacts should be not lower than 5A.
Wiring terminal: continuous current allowed for wiring terminal should be not lower than 10A.

Appearance and form of primary arrangement

Single busbar double isolating form

Single busbar single isolating form

Purchasing procedures

1.Customer provides us a technical specification according to their project requirements. We shall prepare the general arrangement drawing of the HGIS according to customer's technical requirements. When our design proposal is agreed and confirmed by our customer, the drawing will be used as the basis for cost calculations and future design input.

2.When the contract is effective, we shall carry out detail project design, and provide our customer with necessary technical documentations, including primary single line diagrams, layout drawing, foundation requirements drawing, sectional drawing and secondary schematic drawings, etc. We shall work closely with our customers to ensure a smooth and successful project execution.