1 introduction I used to use the PGJ1 - in 400 v switch rooms
5 type reactive power compensation, the screen in a BCMJ type parallel capacitor
10 only screen, each rated output 16 kvar, rated voltage is 0.
4 kv, rated current 25 a, category - temperature
45 ℃ to 25 ℃ / connection.
Of the two the cause of the accident has made the earnest analysis and processing.
Cause analysis and treatment 2.
1 high environment temperature the reactive power compensation installation screen in the 400 v switch indoor, indoor total of 8 sets of switchgear, and area only 30 m2, the opposite is SZ7 -
4 transformer room, the overall poor ventilation condition, burning hot summer switch indoor temperature as high as more than 48 ℃, thus the environment temperature is one of the reasons caused an explosion of the capacitance.
Compensation should be moved to a single screen through risk control system, and should be shown in capacitor shell with wax tablets (
, show that the temperature of the personnel on duty can come from indirect monitoring capacitance of medium temperature.
From formula 2 voltage unstable we QC = 2 & PI;
Can be seen in the fCV2: capacitor is proportional to the square of the capacity of reactive power and voltage.
When the voltage is lower, the capacitor reactive power capacity will be effected according to the voltage is proportional to the square of the corresponding reduction, can not make full use the capacity of the capacitor.
When running voltage rise will increase the rise of temperature of the condenser, even the heat balance of the capacitor damage caused by the capacitor explosion.
So the gb regulation: capacitor allowed in 1.
Long running under 1 times the rated voltage, but every 24 h.
15 times the rated voltage under the operation time shall not exceed 30 min.
I plant 400 v voltage is unstable, voltage fluctuation range of 0.
Ue to rated voltage 400 v)
, valley electricity often about 450 v, the running time for 7 h, this is our factory capacitor explosion burn for another.
Because of SZ7 -
Is 800 kva power transformer on-load voltage regulating transformer, to solve this problem simply setting a KYT -
Type 2 on-load voltage regulating controller, voltage is always less than one thousand yuan investment can control for the nominal voltage.
3 the existence of the harmonic current our factory adopted high power thyristor rectifier dc power as a rotary kiln and compensation parallel operation screen.
Due to the thyristor device connected to the electricity grid operation, objectively had a higher harmonic generator effect, can cause circuit of voltage and current waveform distortion.
The existence of the harmonic current often abnormal noise in the condenser, serious when capacitor caused inflation, this is the third cause of capacitor explosion.
The main reason is: (this happens
Higher harmonic current superposition of the base wave current, is always the capacitor current increase,
A high order harmonic impedance in the system and cause parallel resonant capacitor between the capacitive reactance, flowing into the capacitor current multiplied;
Capacitor inside for a certain time high harmonic generation is local series resonance, that cause over load.
Three measures to prevent these happen, can be in every phase of the compensation capacitor Banks to limit the current through a hollow reactor.
The synthesis of the capacitor circuit reactance for higher harmonic, the inductive reactance.
In higher harmonic, harmonic three times was short circuit for transformer delta connection, so it is for more than five times the harmonic measures.
If choose the series reactor reactance make harmonic resonance, 5 times 5 times harmonic is short circuit, for more than 5 times harmonic higher harmonic, due to the capacitance loop into inductive, so waveform is improved, thus fundamentally eliminating the possibility to produce resonance.
Anti resonant series hollow reactor reactance can be calculated: namely XL>
4% XC type: L series reactor inductance, H;
Capacity of compensation capacitor C F;
XL series reactor inductance, & Omega;
The capacitive reactance XC compensation capacitor, & Omega;
Therefore, the reactance of the series reactor is about more than 4% of the capacitive reactance.
The occurrence of accidents due to considering the system low frequency capacitor capacity reduction, actually choose XC impedance is 5% ~ 6%.
After the disposal of the above analysis, the reactive power compensation to screen the effect of the safe and energy-saving operation.
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