Large high voltage motor starting design

Abstract: this paper expounds the enterprise 6 kv power grid, the grid short-circuit capacity are smaller and the high voltage motor capacity is big cases starting scheme selection, starting design calculation, analysis and determination, as well as in actual driving starting data assessment, etc.
Keywords: power supply; High pressure synchronous motor; Starting; design
1 words before
Our country industrial and mining enterprises of the power supply system is a lot by 6 kv distribution voltage, in 6 kv distribution grid, if electric equipment in large capacity (2000 kv above) high voltage motor, the motor starting process, power grid voltage will produce large fluctuation, will directly affect the quality of power supply and power grid in other electric equipment normal operation and service life, this kind of situation is not allowed to appear. In order to solve this problem, in electric control design is usually adopted to rotary joints reduce motor terminal voltage way starting. Therefore, in the design, must according to the power grid conditions, for large high voltage motor starting for starting calculation, check and choose the right starting method and reasonable starting equipment.
2 grid conditions and high pressure motor of the main technical data
2.1 grid conditions
A certain air separation plant power supply electric control system from the superior decompression station, 6 kv voltage, decompression station outlet side of the maximum, minimum short circuit capacity for: Smax = 230 mva, Smin = 130 mva; Decompression station to air separation plant high pressure distribution room distance of 400 m, by two root 185 best callus induction copper core parallel feed, reduced to
rotary union air separation plant 6 kv cable into line in maximum, minimum short circuit capacity for:
Sbsmax = Sj / (Sj/Smax + XL) = 212.31 MVA
Sbsmin = Sj / (Sj/Smin + XL) = 123.46 MVA
Type of Sj - reference capacity, take 100 mva
XL - cable reactance scale MAO value, XL = 0.041 Ω
Therefore, the air separation plant 6 kva bus maximum, minimum capacity for: Sbsmax = 212.31 MVA, Sbsmin = 123.46 MVA; Air separation plant 6 kva bus for single bus section are operating, and of 3700 kw motor joint in Ⅰ period of bus to
fiber optic rotary joint the higher level, Ⅰ period of bus preliminary joint load reactive power: Qx = 2.10 MVA.
2.2 high voltage motor of the major technical data
This air separation unit using shenyang blower factory production of turbine air compressor, the drive motor as Shanghai electrical machinery plant production T3700-4/1430 large high pressure synchronous motor.
Motor parameters: rated power: 3700 kw; Rated voltage: 6 kv; Current rating: 408 a; Rated capacity: 4235 kva; Starting current multiple: six times; Power factor: cos Φ = 0.9; Frequency: 50 hz, Speed: 1500 r/min, Motor starting torque relative value: 1.8; Unit static resistance torque relative value: 0.3; Synchronous motor pull in torque relative value: 1.18; Flywheel moment: 385 kg. M2; Motor longest allow starting time: 40 s; Motor allows continuous starting number: 2 times.