【導(dǎo)讀】設(shè)計，它已開始涉及多個方面并加強(qiáng)了對質(zhì)量安全、節(jié)約能源等方面的要求?，F(xiàn)代的建筑電氣設(shè)計，更加人性化，規(guī)范化，智能化，安全化。設(shè)計是一個對建筑物最基礎(chǔ)的構(gòu)思表達(dá)，它是在理論的基礎(chǔ)上，對實(shí)踐最規(guī)范的整理，經(jīng)過反復(fù)推敲、不斷深入發(fā)展和進(jìn)行評價的基本上最終實(shí)現(xiàn)成果。供電和照明，而今天一般將其設(shè)計的內(nèi)容形容為強(qiáng)電和弱電。這種分類以電壓的高低為依據(jù)，容易理解，所以很快被人們所接受。設(shè)計過程從由簡入深，各階段思維的廣度、深度都不同，表達(dá)方式、工具也可能是多樣化的。及設(shè)計選擇的結(jié)論。主要涉及強(qiáng)電，其中強(qiáng)電包括：住宅用電負(fù)荷計算；照明配電平面圖設(shè)

　　

【正文】 t, in addition to meeting regulatory requirements, it also need to consider the highpressure cabis, transformers and low voltage power supply cabi by order of arrangement, especially in low voltage distribution cabi to feed the cable smooth and easy inspection duty problems are not seriously consider the construction of the cable crossing will cause more long detour, a waste of floor space, and convenient inspections and other issues. 4small fire load power supply In the design of large mercial projects often encounter small fire load of electrical equipment and more dispersed distribution, if fed by a substation, a substation will be fed a lot of lowvoltage lowcurrent counter circuit breaking capacity circuit breaker and conductor of the dynamic and thermal stability in a certain extent. According to GB500451995 “fire protection design of tall buildings,” rule “should be used in Fire Equipment dedicated power supply circuit, the power distribution equipment shall be provided with clear signs.” Interpretation of the provisions of the power supply circuit means “from the lowvoltage main distribution room (including the distribution of electrical room) to last a distribution box,and the general distribution lines should be strictly separated.” In this design, the use of methods to increase the level of distribution, that is different from the substation bus segments, respectively, a fire fed a special circuit, set in place two distribution cabis,distribution cabis and then the resulting radial allocated to the end of power supply circuit means “from the lowvoltage main distribution room (including the distribution of electrical room) to last a distribution box, and the general distribution lines should be strictly separated.” In this design, the use of methods to increase the level of distribution, that is different from the substation bus segments, respectively, a fire fed a special circuit, set in place two distribution cabis, distribution cabis and then the resulting radial allocated to the end of the dual power to vote each box, so that not only meets the specification requirements for dedicated power supply circuit, but also to avoid feeding the substation level of many small current loop. 5, the choice of circuit breaker and conductor Commercial real estate projects use the room as the uncertainty in the choice of circuit breakers and conductors must be considered in a certain margin to meet the needs caused by adjustment of the load changes. According to this characteristic, increased use in the design of the plug buspowered, not only meet the requirements of large carrying capacity, and also allows the flexibility to increase supply and distribution, are reserved in each shaft in the plugbox backup in 22 order to change, according to changes in upper and lower load, to adjust. For example: a bus is responsible for a shaft 1 to 3 layers of power, when a layer due to the change in capacity increases, while the 3layer capacity is reduced, you can use a spare plug box layer off the 3layer 1 layer capacity rationing. This level distribution in the substation, select the circuit breaker to choose the setting value when the circuit breaker to adjust to changes at the end to adjust the load setting value。 in the bus and the transformer circuit breaker according to the choice of the general framework of values to select. For example: Route certain equipment capacity 530Kv, Kx take to calculate current of 704A, select the frame circuit breaker is 1000A, tuning is 800A。 current transformer for the 1000/50。 bus carrying capacity for the 1000A, this road can meet the maximum 1000A current load requirements, even if there is adjustment, power distribution switches and circuit can not make big changes. This course covers Molded Case Circuit Breakers and related products. Upon pletion of Molded Case Circuit Breakers you will be able to: ? Explain the need for circuit protection ? Identify various types of over current protective devices ? Explain the basic electromechanical operation of a circuit breaker ? Identify various types of Siemens circuit breakers ? Identify circuit protection ratings for various types of Siemens circuit breakers ? Describe timecurrent characteristics on a timecurrent curve ? Explain the benefits and function of circuit breaker coordination ? Identify internal and external circuit breaker accessories ? Explain the difference between molded case circuit breakers and insulated case circuit breakers Current flow in a conductor always generates heat. The greater the current flow, the hotter the conductor. Excess heat is damaging to electrical ponents. For that reason, conductors have a rated continuous current carrying capacity or current protection devices, such as circuit breakers, are used to protect conductors from excessive current flow. These protective devices are designed to keep the flow of current in a circuit at a safe level to prevent the circuit conductors from of Over current Protective Devices Circuit protection would be unnecessary if overloads and short circuits could be eliminated. Unfortunately, overloads and short circuits do occur. To protect a circuit against these currents,a protective device must determine when a fault condition develops and automatically disconnect the electrical equipment from the voltage source. An over current protection device must be able to recognize the difference between over currents and short circuits and respond in the proper way. Slight over currents can be allowed to continue for some period of time, but as the current magnitude increases, the protection device must open faster. Short circuits must be interrupted instantly. Several devices are available to acplish this. Fuse： A fuse is a oneshot device. The heat produced by over current causes t