电工学常用公式（Common formulas for electrical engineering）.doc

电工学常用公式（Common formulas for electrical engineering） This article is contributed by simachfeng_bdu DOC documents may experience poor browsing on the WAP side. It is recommended that you first select TXT, or download the source file to the local view. Calculation formula for common use in electrical engineering Liu Junchang, Dongping County Power Supply Bureau of Shandong province (271500) First, the average active power, current power, reactive power and power factor of a period of time are calculated by using three active watt hour meters, current transformers, voltage meters and current meters on the low voltage switchboard. (1) the active power is calculated by using three-phase active watt hour meter and current transformer N measurement meter disk speed K - meter constant (each kWh RPM) variable AC T -- required to measure N time S CT current transformer (two) basic balance in three-phase load and stable situation, the use of voltage meter, ammeter indicates the number of calculation of apparent power Type (three) the reactive power can be calculated when the active power and apparent power are calculated (four) the power factor can be calculated according to the active power and the current power 1 cases of a unit distribution plate is provided with a 500 rpm / kWh three 100 / 5 meter, current transformer, voltage meter 400V, ammeter indication in 22A, in the three-phase voltage and current balance stability under the condition of test, the meter disk rotation speed 60S 5 turns. How much is the active power, the present power, the reactive power and the power factor? [1] numerical solution into the formula (1), P = 12kW to the active power of the values into the formula (2); have apparent power S=15kVA based active power and apparent power into the formula (3), Q=8l kVar to the reactive power from the active power and power now into the formula (4) well, the power factor cos = 0.8 two, with a stopwatch test error of electric meter method (a) the selected disk s