High-voltage Shunt Capacitor
High-voltage Shunt Capacitor
The high-voltage shunt capacitor is mainly used for the AC power system with 1kv power frequency (50Hz or 60Hz) and above to increase to power factor and improve grid quality.
The high-voltage capacitor is composed of many capacitor units, which are usually connected in series or in parallel into several groups to obtain the rated voltage and capacity of single capacitor we need:
The rated voltage of capacitor depends on the quantity of capacitor groups connected in series.
The rated capacity of capacitor depends on the quantity of each group of capacitors connected in parallel.
The composition of each capacitor unit: two pieces of aluminum foil form electrode; The special high-quality polypropylene film (easy to inject) forms the insulation layer. The wired capacitor assembly (referred to as “capacitor core”) is placed in a stainless steel shell and is fitted with the insulating porcelain bushing or terminal for connecting the device.
High quality double-sided roughing polypropylene film is adopted to ensure good impregnation. The all-film dielectric capacitor has longer service life and has the following characteristics:
● Extremely high resistance to strong electric field
● High thermal stability and low power dissipation, especially for the high power capacitor bank
● Good partial discharge absorption performance
● High impedance and resistance to transient overvoltage and overcurrent for insulating medium
● The capacitance changes slightly with temperature
2.2 The adopted impregnant has very high chemical stability, very high gas absorption ability and local discharge extinction performance, and also has the following characteristics:
The foil folding and extruding structure is adopted for the element to improve the electric field distribution at the edge of polar plate and increase the level of partial discharge.
The pressure joint type high strength porcelain with high sealing performance is adopted for capacitor bushing. The welding between bushing and shell is argon arc welding. The mechanical strength and sealing performance is high.
The shell is made of stainless steel plate and implemented paint spraying after shot blasting, which makes the paint surface smooth and beautiful, and has strong anti-corrosion andstrong resistance to blasting.
Small dielectric loss: tg<0.02%.
Excellent ratio characteristic and high electric strength.
The high reliability internal fuse has uniform material, excellent ampere-second characteristic and reliable movement.
Main technical parameters
Voltage class: 1kV~24kV
Rated frequency: 50/60Hz
Rated capacity: 100kvar ~1000kvar
Capacitance tolerance: 0~+5%
Insulation dielectric loss and total loss
● Insulation dielectric loss: 0.1 W/kvar (after operating 500 hours)
● The insulation dielectric loss plus discharge resistance, internal connections and internal fuse losses are total loss, which is approximately 0.07 to 0.15 W/kvar.(see Figure 1 and Figure 2)
● Capacity changes with temperature (see Figure 3): on average: 2 x 10-4/℃
Temperature class: - 25/D
It is allowed to operate for a long time at 1.0 time of rated voltage and can operate for no more than 8 hours every 24 hours at 1.1 times of rated voltage.
It is allowed to operate at the steady state overcurrent (valid value is 1.30 times of rated current) caused by overvoltage and high-order harmonic. For the capacitor with maximum positive deviation of capacitance, the steady state overcurrent is allowed to reach 1.43 times of rated voltage.
The capacitor has two or three terminals.
The capacitor has a built-in discharge resistor, and the discharge residual voltage of each capacitor unit is 75V or lower.
● The internal fuse is used to isolate the faulty capacitor unit to ensure that the capacitor or capacitor bank connected therewith continues to operate safely;
● The single-phase capacitor can be completely protected by the internal fuse and unbalanced protection device.
Pressure monitoring device
● The pressure inside the capacitor shell is monitored by a pressure sensor. Once the set threshold is exceeded, the contact of monitoring device will be activated to disconnect the capacitor from power supply in time, thus preventing gas generation in the capacitor shell and avoiding cracking and explosion of the shell body;
● Three-phase capacitor can be fully protected by using pressure monitoring device and H.R.C fuse.