High pressure part:
(1) High voltage power supply system
1) The capacity of a 10kV municipal cable is 8000~ 10000kVA, which is derived from the current carrying capacity of the cable. S =1.732× u× I× k1/K2/K3 (k1:line load rate, k2: transformer load rate, k3: simultaneous coefficient);
2) Only in three cases can it be called primary load power supply. Hair, hair; 35kV (self-provided);
3) The design of the switch station is similar to that of the high-voltage distribution room, and the main difference lies in the metering method. The power supply department's review of drawings is mostly in the measurement method, precision grade and equipment selection.
4) The switch station can be located on the first floor, the first floor or the ground. Either way, an independent cable channel is needed, and the possibility of outdoor rainwater backflow should be considered.
5) The working power supply can be DC or AC +UPS.
6) Beijing's high-voltage primary line is not applicable to the whole country, so it is necessary to refer to local general standards and industry standards in advance.
(2) Power transformation and distribution system
1) Strictly use the load calculation book to calculate and select the transformer and low-voltage outlet.
2) For the single bus sectional system, the three-stage load shall be provided with a voltage loss release to avoid the load impact after power conversion.
3) Buildings with large refrigeration capacity should be equipped with special transformers.
4) The low-voltage screen should be arranged according to the load grade and load nature as far as possible.
5) The substation should be provided with a power cabinet, and all auxiliary power sources such as lighting, ventilation and air conditioning should be connected from here.
6) Radial power supply circuit can be equipped with superior leakage monitoring; The main power supply must be set in the floor main box.
(3) Low voltage power system
1) The distribution system is completely separated according to the load grade, load usage, ownership of property rights and use position, which is the only way to solve the problems of clear measurement, convenient management and maintenance.
2) Be sure to calculate the filling rate of the outgoing line of the substation and the trunk bridge of the electric well, which shall not be greater than 40%. In order to facilitate the later expansion and laying of branch cables, it is suggested that the filling rate should be controlled at around 25%.
3) Fire fighting (enclosed) shall be separated from ordinary bridge (free bridge) as far as possible, and the vertical passages in the electric well shall be separated as far as possible.
4) The cable carrying capacity should consider the correction factor under the laying environment, temperature and mode, and it is recommended to use a bridge below150 mm. ..
5) Single-core cable has good heat dissipation, so the current carrying capacity is 20% higher than that of multi-core cable.
6) It is forbidden to carry any equipment except water chillers, chilled water pumps, cooling water pumps and cooling towers for special refrigeration transformers.
7) The voltage drop of long-distance power supply cable in roof ventilation and cooling tower shall be calculated.
8) It is best to use passive signals in fire fighting linkage control to reduce the dependence on the driving current of fire fighting system modules.
9) Electrical devices should be arranged in unchangeable parts of buildings as far as possible, such as constructional columns, concrete walls and stair partitions.
10) secondary power distribution is a way to solve the problems of many fire areas, small cable section and large voltage drop.
1 1) When the calculated current exceeds 400A, it is necessary to consider the rationality of double spliced cable single loop and single cable double loop.
(4) Equipment installation and selection
1) cable selection should be based on higher standards, such as mineral insulation, low smoke and no halogen.
2) The incoming line of trunk power distribution box adopts protection switch.
3) Pay attention to the selection of seven distribution cables starting with Y-δ and QF, KM 1/2/3, KH and CT to avoid waste.
4) The local maintenance button of the equipment shall have the function of cutting off the power supply or self-locking.
5) The thermal magnetic tripping should be cancelled in QF for fire power distribution, and the electromagnetic tripping type /3200 should be selected.
6) The PC-level mutual throw switch without protection switch adopts three-stage type, and the "0" position is set for maintaining isolation.
7) Add a filter device at the inlet and outlet of the frequency converter to reduce the harmonic influence on the superior power supply network, otherwise the neutral line section needs to be increased.
8) Mineral insulated cable is used for the main fire line, and metal sheath can be used for the PE line.