The commonly used plastic shell type low voltage circuit breaker ( Figure) Model and choose

Low voltage circuit breaker is also called automatic switch or automatic air circuit breaker. It is a kind of both can be switch to use, but also has automatic protection function of low voltage electrical circuit. ( 1) The breaker is composed of three parts: contact and arc extinguishing system - — On-off circuit components of trip - — Abnormal state detection circuit and react, namely the protective action of parts; The operating mechanism and automatic tripping institutions - — The middle connection parts. ( 2) Figure is the circuit breaker features, structural principle diagram. Chart of three to contact 2 series in a protected three-phase main circuit. Manually pull (button for the 'close' position ( Not draw in figure) When the contact 2 by the lock button 3 keep in closed state, the lock button 3 by 4 support the toggle hook. Pull (button to switch points off for 'points' position ( Not draw in figure) Open, toggle hook 4 by leveraged 7 ( Toggle hook can turn axis 5) , contact 2 was spring 1 and circuit breaker. Automatic switch automatically breaking, it is by electromagnetic tripping device, undervoltage tripping device, 6 11 and 12 to toggle hook thermal trip 4 by leveraged 7 top open and complete. Electromagnetic trip 6 coil and main circuit in series, when the line work, cannot be produced by the electromagnetic suction armature 8, absorption occurs only when the circuit produce very big over current, short circuit or electromagnetic suction to 8 and armature, impact leveraged 7, toggle hook up four, make contact 2 disconnect, which the circuit breaker. Undervoltage tripping device, 11 by the coil in parallel in the main circuit, when the line voltage is normal, undervoltage tripping device produced by electromagnetic suction can overcome the spring tension of the 9 and 10 and armature, if the line voltage has dropped below a certain value, the tensile strength of the electromagnetic force is less than the spring 9, armature were spring 9, 10 armature impact leveraged 7 make open toggle hook, contact points 2 is broken circuit. When the line overload occurs, overload electrical current overheating trip of heating elements and make the bimetallic strip 12 13 heated bending, then hit 7 toggle hook up, make off contact, and overload protection. According to different purposes, automatic switch can be equipped with different trip. ( 3) According to the structure classification automatically switch has universal type ( Frame type) And the plastic shell type ( Device type) Two kinds. Molded case type automatic switch is commonly used in control circuit as a power switch or as control and protection is not frequent start and stop the motor switch, and used in hotels, airports, stations, large-scale construction of the lighting circuit. Its mode of operation for manual, basically have pull (type and push button. Universal type ( Frame type) Mainly used for power supply and distribution system. Automatic switch compared with knife switch and fuse, has the following advantages: compact structure, convenient installation, safe operation, and in the short circuit protection, because using electromagnetic trip will be the power cut off at the same time, to avoid the possibility of motor open phase running. In addition, automatic switch trip can be repeated use, don't have to be replaced. ( 4) Common molded case circuit breaker mainly DZ5, DZ10, DZ15, DZ20 series. Low voltage circuit breaker model meaning illustrate as follows, the technical data are shown in table 1 Table 1-2 2 DZ15 series molded case circuit breaker models very amount of current ( A) Rated voltage ( V) The rated short circuit breaking capacity ( KA) Mechanical life ( Ten thousand times) Electrical life ( Ten thousand times) DZ15- 4016、10、16、20、25、32、40AC22031. 51. 02年3 ac380dz15 - 20 63110年,16日,25日,32岁,40岁,50岁,63 ac22051。 00. 62, 3, 4 ac380 for motor protection circuit breaker thermal trip to undertake choosing according to the rated current of the motor and setting, while the instantaneous over-current electromagnetic trip to choose according to the rated current of the motor 12 times, to ensure that the peak value of the motor starting current is not action.