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(4) Deepen the foreign exchange cooperation of new materials, theoretical calculation of line loss of low-voltage lines

Abstract: the power loss of low-voltage lines themselves; Power loss of low-voltage household line; Electric energy loss of user's electric energy meter; Electric energy loss of user's motor; Electric energy loss of other electrical equipment of users

key words: electric energy loss of low-voltage line Untitled Document 1 main composition of theoretical line loss of low-voltage line (1) electric energy loss of low-voltage line itself; (2) Power loss of low-voltage household line; (3) Electric energy loss of user's electric energy meter; (4) Electric energy loss of user's motor; (5) Power loss of other electrical equipment of users. 2. The general calculation formula of theoretical line loss of low-voltage line is: △ a=nk2i2pjrdzt × Where n - electrical structure coefficient at the outlet of low voltage side of distribution transformer: ① single-phase two-wire lighting line n=2; ② Three phase three wire braking power line n=3; ③ Three phase four wire hybrid power line n=3.5. K - shape coefficient of load curve, that is, the correction coefficient for average current (IPJ) taken into account the change of load curve. The value of K is selected according to table 1 of the recommended theoretical calculation value. Table 1 load curve shape coefficient K value table minimum load high molecular waterproof material water swelling rubber gb/t18173.3 ⑵ 002 rate 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 K value 1.17 1.09 1 The jaw distance of the tensile testing machine is 125mm, and the test speed is 125mm/min ± 12.5mm/min. Stretch the sample to a certain elongation of 051.03 1.02 1.01 1.00 1.00 1.00 (minimum load rate a= minimum load/maximum load) T - the monthly power supply time of the line, hrdz - the equivalent resistance of the line conductor, Ω equivalent resistance can be calculated according to the following formula: where IZD - the measured maximum current at the low voltage outlet of the distribution transformer, Aizdok - measured maximum current of each section of low-voltage line, ark - resistance of each section of low-voltage line: rk=rokik, Ω n - structural coefficient of low-voltage outlet of distribution transformer (as before) NK - structural coefficient of each section of low-voltage line, with the same value as n IPJ - monthly average value of load current at the head end of the line, a can be calculated and selected according to the following different conditions: ① if the distribution room is equipped with ammeter and recorded, The monthly average load current can be calculated directly. ② If an ammeter is installed but there is no record, a representative period can be selected to read the current value, and then calculate the average load current value. ③ If the ammeter is not installed, you can select a representative period and directly read the load current value with the clamp ammeter. ④ When the distribution room is equipped with active energy meter and reactive energy meter, it can be calculated according to the following formula: UPJ - the average operating voltage of the line, kV, or the rated voltage (UN) can be approximately used to replace ap - the monthly active power supply of the line, kW · HAQ - the monthly reactive power supply of the line, kvar · HT - the monthly power supply time of the line, H ⑤ if the distribution room is equipped with active energy meter and power factor meter, it can be calculated according to the following formula: COS in the formula φ PJ -- average difference of line load power factor 3. Calculation of theoretical line loss of low-voltage household line. The connecting line from the low-voltage line to the user's watt hour meter and from the watt hour meter to the electrical appliances is called household line (or lower household line). The theoretical line loss can be calculated as 0.05kw · h per 10m. When the length of household line is l, the monthly loss is: Δ A=0.05l/10 (kW · h) 4 theoretical line loss calculation of electric energy meter (1) monthly loss of single-phase electric energy meter is calculated as 1kW · h; (2) The monthly loss of each three-phase three wire meter is calculated as 2KW · h; (3) The monthly loss of each three-phase four wire meter is calculated as 3kw · H. 5. Calculate the electric energy loss of the motor. The difference between the rated input power and the rated output power of the motor is its lost power (including iron loss, copper loss, etc.). Straighten the hanger suspender; (5) The perpendicularity of the main shaft and the test bench platform multiplied by the operating hours of the month is its power loss, and its calculation formula is: un - the rated operating voltage of the motor, kvin - the rated current of the motor, ACOS φ N - rated power factor of motor PN - rated power of motor, kwt - monthly operation time of motor, H6 its

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