I. Overview 
KYN28A-12 (Z) armoured away AC metal closed switch equipment (also called the GZS1 switching equipment) from Xi’an SenYuan company development and technology transfer within the indoor mid-voltage switch equipment. It applies to three-phase AC 50 Hz power systems for the acceptance and distribution of electric and control, protection and monitoring circuits. 
Line with standards: 
GB3906-91 "3 ~ 35kv AC metal closed switch equipment" 
GB11022-89 "high-voltage switch equipment common technical requirements" 
IEC298 (1990) "rated at 1 kV higher and 50 kV lower AC metal closed switch equipment and control equipment" 
DL404-91 "indoor AC high-voltage switchgear order technical conditions" 
Switch equipment designed according to armoured metal closed switch equipment in GB3906-91. The switchgear and taken can part in the middle (that is, hand cars) two major components (see Figure 1) make the overall. Switchgear has four separate rooms, shell level of security IP4X, when the doors of the small rooms and the circuit breaker rooms open level of security to IP2X. It has elevated in-out line, cable and other functions, combined with the various programmers to be forms of distribution equipment. The switching equipment can be installed commissioning and maintenance below. Therefore it can makes double arrangement and installation against wall back-to-back, increased security, flexibility and reduced area. 
4.1 Shell and others 
Switch equipment shell is adopt imports Al-Zn review thin iron plate, CNC machining and take multiple flap process. This will enable the switchgear has not only high accuracy, highly corrosion-resistant and anti-oxidation, but the use of multiple flap, switchgear equipment has lighter weight, higher mechanical strength and aesthetic appearance. Switchgear adopted assembled structure, and connected with pull riveting high-strength nuts and bolts. This will enable the production processing cycle short, parts and components with high universality, little spa cement and facilitate production. 
4.2 Hand car 
Hand car’s skeleton used thin steel assembly after the machine processing by GNC. Mechanical interlock is safe, reliable, and flexible. According to different uses, there are breaker-hand car, voltage reactor-hand car, measurement-hand car, and isolation hand car. Various types of hand cars change with module, the building blocks, can be 100 percent free exchange with the specifications-hand car. Hand car in the counter has a withdrawal (segregation) position and work location, location of each of the respective positioning system to ensure reliable interlock and must operate according to procedures. Various hand cars are used turbo rocking forward and withdrawal, easy flexible operation, and suitable for various duty personnel When need switchgear hand cars away, with a dedicated transit vehicles, can easily retrieve a variety of inspection, maintenance, and use of home-style, the cars are small shape, extremely convenient for inspection and maintenance. 
4.3 Separated room 
Electrical components in witch equipment have their own independent separated room: circuit breaker -hand car room, bus room, cable room, relay instrument room. Room’s level of security reached IP2X; beside relay room, three other rooms have their pressure relief channel for each. As a result of the buy-in the form, cable room location has increased significantly, so equipment can access multi-channel cable. 
4.3.1 Circuit breaker room 
Room installed track at both sides for the 15-hand car in the cabinet moves from isolated location to work location. Static Contact box 6 installed on clapboard 13 (valve) in-hand car rooms on the walls. When hand cars move from the location to work location, in the course of the upper and lower static Contact box on the trap door and hand car linked, at the same time open automatically. When moving to the opposite direction, the valve is closed automatically until a certain location-hand car back to full coverage of live static contact box, form an effective isolation, and because of the trap door is not linked, in the overhaul, they can live side of the trap door locked, so as to ensure overhaul maintenance persons do not live in touch. When the circuit breaker room doors closed, hand cars can also be operated through the door observation windows, and observed at the location of the indoor-hand car, display on-off gates, and storage conditions. 
4.3.2 Bus room 
The main bus 4 splicing each other through a single connection (see Figure 2), fixed through branch bus 2 and static contact box. The main bus and contact bus are the rectangular cross-section of copper row; two-roots bus bar parallel for a large current load. Branch Bus connects static contact box 6 and main bus through the bolts; do not need other support pines. For special needs, bus and connectivity available sets of thermal insulation kits and-bolts coverage cap, adjacent bus counters with three fixed casing. This bus link between the airs retained by the buffer, if there is internal fault in the Arc, we can prevent it through melting, and the casing 3 can limit the accident in the room effectively without spread to other counters. 
4.3.3 Cable room 
Switch equipment used in home style, therefore cable room space large. Current mutual inductance 7 and earth switch 8 installed on the room wall, arrester10 installed on the lower part of every room. When hand cars 15 will and level partitions 17 taken away, construction personnel will be able to enter the cabinet from the front for installation and maintenance. Cables connect the conductors, and each phase can be one to three single-core cables. When necessary, each phase can connects six single-core cables, the cable connecting the preparation of a joint counter at the end of the closure could dump non-metallic or non-metal seals magnetic board to ensure that the construction convenience. 

4.3.4 Relay Meter Room 

Relay Meter can install the relay components, instruments, live monitoring indicator, and the special requirements of the secondary equipment. Control lines lay in enough space to the trough, and a metal plate, can isolate from the second line and high-voltage rooms. Tunings on the left is for controlling its small line and leading to the introduction of the reserve. Switchgear its own internal deployment of a small line on the right. Relay Meter room also allow for the construction of the bus through the small hole on the roof. When wiring, instrument room for flip-top cover to facilitate the installation of small bus.

4.4 Prevent misuse interlock devices 
There are safe and reliable interlock devices in switch equipment, to fully meet the requirements of anti-five. 
a. meter room with tips on the door of the KK-button or switch to prevent the misuse of damage the circuit breaker. 
b. circuit breaker-hand car in the test or work location, at a circuit breaker in order to operate, but also in circuit breaker switch on, the hand cars can not be moved to prevent the misuse of the load push-pull circuit breakers. 
c. only when the earth switch in the location of the gate, the circuit breaker-hand car to go to the location of disconnect. Only when the circuit breaker in the off-hand car location, in order to switch on the earth switch operation (the earth switch can be installed with voltage display devices). This has charged prevent misuse of the earth switch. 
d. earth switch in the location of the gate when the Commissioner of circuit breakers. The earth switch in the location of the gate, under the door and are unable to open the back door, preventing the mesentery charged interval. 
e. breaker-hand car in the test or do the work place, but not control voltage, only can sub-gate manually, not closing. 
f. breaker-hand car in the work location, the second plug was locked ,and can not be open. 
g. the switchgear electric chain can be installed. 
The switching equipment can also operate in the earth switch on the body to install locking devices to enhance the magnet reliability, its orders according to the needs of users’ choice. 
4.5 pressure relief devices 
pressure relief devices are equipped at the top of breaker-hand car room, bus room and cable room, when the circuit breaker or bus internal arc, accompanied by the emergence of Arc, switchgear internal pressure increased, the special ring installed on the door closed the front of counters, the metal plates at the top of pressure relief equipment will be open automatically to release pressure and the excretion of gas to ensure that the switchgear and operators security. 
4.6 Second- plug and hand car location interlocking 
the second line on switch equipment and hand car are contacted by manually second plug. Second plug the dynamic contact through a nylon expansion of the corrugated-hand car associated with the circuit breaker, the second static contact installed on the top right-hand car room. Only when circuit breakers hand car on disconnect location, the second plugs can be on and disarm. When circuit breakers-hand car on work position, because of the circuit breaker-hand car locked bodies were electromagnets, the circuit breaker can only to get through but not be closing before second-hand car plugs be connected. 
4.7 Charged display devices 
If the user demand, the switchgear can install optional charged display devices for detecting circuit running once .The device composed from the high-voltage sensors and monitors, and it will not only prompt high-voltage circuit charged situation, but also meet with electromagnetic locks to prevent the commissioner charged with the earth switch and mesentery charged interval, so as to matching products to enhance the anti - misuse performance. 
4.8 Prevent dew and corrosion 
In order to prevent the high temperature or dew from temperature changes in climate, the circuit breaker room and cable room were installed heater, in order to use in the environment above and to prevent corrosion. 
4.9 Grounding devices 
In cable room, there is a separate 10 × 40mm ground copper row. The row can run through the counters, and contacts well with switchgear. This grounding row is used for the direct ground components. At the same time for switchgear contacted with Al-Zn review board, so the entire switchgear is in a good state of grounding to ensure that the operator and switchgear safety.