9.2　General Items

9.2.1　The installation of a low-voltage circuit breaker shall be in accordance with the following requirements:

1　The moving parts of circuit breaker shall not be stuck by any parts of the arc chute during the closing and opening of contact terminals.The contact surface of every contact terminal shall be smooth，and the order of opening and closing and the opening distance of the moving and fixed contact terminals shall meet the technical product specification.

2　The low-voltage circuit breaker should be installed vertically，with the inclination not more than 5°.Where it is used with a fuse，the fuse shall be installed at the side of power supply.

3　The opening and closing position of operating handle or drive rod shall be correct，and the operating force shall not exceed the rated value.The wiring of electrical operating mechanism shall be correct.The auxiliary contacts of switch shall act normally and reliably，and during the switching-on operation，the contact points shall be in good contact and the switch shall not bounce.

4　The operation，test and isolation positions of open frame circuit breaker shall be clearly marked.When in idle run，it shall be pushed or pulled freely and the mechanical interlock shall function reliably.

5　The low-voltage circuit breaker equipped with semiconductor release shall be wired according to required order and the release action shall be reliable.

9.2.2　The installation of DC quick breaker shall be in accordance with the following requirements:

1　The circuit breakers shall not be inclined，impacted and shaken violently during the installation，and anti-vibration measures shall be taken according to design requirements for between the channel steel of foundation and the base.

2　The distance between the centers of poles of a circuit breaker and the distance between adjacent devices or buildings shall not be less than 500mm.A space not less than 1000mm above the arc chute shall be kept.

3　The outlet terminal shall not be exposed to any additional stress when connected to the bus.The distance between the support point of bus and the circuit breaker shall not be less than 1000mm.

4　If the contact terminal and coil are marked with positive and negative poles，they shall be wired according to the poles of main circuit.The control lines shall be separated from the main circuit.

5　Arcing contact and main contact shall act the correct order and pickup of armature shall be even.The bearing shall rotate freely and be applied with lubricant.

9.2.3　The installation of low-voltage disconnecting switch，knife switch，changeover switch and fusecombination unit shall be in accordance with the following requirements:

1　Bus disconnecting switch:whether it is installed horizontally or vertically，the blade shall be on the vertical plane and the distance between the bottom of blade and the foundation should not be less than 50mm.

2　During installation of lever operating mechanism，the length of lever shall be adjusted so that it can be operated properly and easily.The auxiliary contact of switch shall be indicated correctly.After changeover switch is installed，the indication of handle position shall correspond to the position of the contact chip.The positioning mechanism shall function reliably and all contact terminals shall contact well at any on-positions.

3　Where the blade is directly connected to the bus，the fixed end of bus shall be securely fixed，the moving and fixed contact terminals shall be able to contact well.Electrical joint compound should be applied to the high current contact terminals.

4　Load switch equipped with a fuse or an arc control device shall be checked after being wired to ensure that the fuse shall be intact and the arc chute shall be free of damage.The arching contacts of different phases shall act for opening and closing in a unified way and shall be fixed securely.

9.2.4　Resistor and rheostat shall not have open or short circuit inside，and the error of DC resistance of them shall meet the requirements of the product technical documents.The outlets of resistance boxes that are installed in a stacked structure shall be fixed with bracket without hindering the replacement of resistance elements.The clamping plate or bolts of outlet wires of resistors shall be marked according to the wiring diagram of equipment.Where they are connected to insulation conductor，measures shall be taken to prevent the insulation strength from being reduced by rise of temperature at the joint.