Lifasa’s cos ϕ correction power capacitors and harmonic filtering for AT are manufactured under the stainless steel container/box base and porcelain terminals. There are two types, depending on the connection mode we are going to use:
- Single-phase (1 or 2 terminals) with internal fuses for connection to the mains via a double star. Recommended for voltage networks above 11 kV or need of high power equipment.
- Three-phase (3 terminals) with internal fuses for direct connection to three-phase mains. Recommended for voltage networks below 11 kV.
The internal composition is a group of elements with single-phase capacities in greater or lesser numbers depending on the desired power/capacity and the future working voltage of the capacitor. These groups are associated in parallel series, thus the final capacitor is obtained with a certain power and operation for high three-phase mains voltages.
The rated voltage of the capacitor determines the number of elements in series and the rated power of the capacitor influences the number of elements in parallel.
The above-mentioned capacitive elements are manufactured using “All-film” technology, with a low-loss roughened polypropylene film and extended aluminium film. With this technology, which replaces the previous “paper-film” technology, losses inside the condenser are considerably reduced, being at values of 0.15 W/Kvar and, in addition, in the event of an internal short circuit, the risk of explosion of the container is eliminated, since the paper produced more gases and a greater increase in internal pressure.
Being a rough polypropylene film, the impregnation of the capacitors is faster, since the liquid penetration between the polypropylene layers, between it and the aluminium electrodes, is improved.
The aluminium foil is laser-cut to smooth the edges and reduce the electric field in these areas. By eliminating the microscopic tips existing on the edge of the aluminium cut with traditional techniques, it is possible to increase the threshold voltage of the corona effect, responsible for anomalies in the capacitors, and gives the product a better tolerance to overvoltages.
According to the recommendations of the IEC 60871-1 standard of 1997, Lifasa’s AT capacitors are able to withstand:
10% overvoltage (1.10 x Un) over the rated voltage 12 hours of every 24 hours.
30% current overload (1.3 x In) over the rated current in continuous operation.
The impregnating liquid used is SAS-40E / M/DBT (JARYLEC C101), a non-chlorinated biodegradable oil (without PCB’s), which has a high resistance to partial discharges and excellent working conditions as a dielectric, in addition to not presenting any type of risk to the environment in the event of failure.
The capacitors are equipped with internal discharge resistors in order to reduce the voltage, after being put out of service, from an initial peak voltage of 1,414 times the nominal voltage to a residual voltage of 75 V 10 minutes according to IEC 60871, or 50 V in 5 minutes according to RAT.
They have an internal protection fuse for each single-phase element, the purpose of which is to prevent the complete disconnection of the capacitor assembly when there is an internal fault due to short circuit or overload, thus isolating the fault and allowing the continuity of service in the rest of the elements.
All this has been the result of the use of the most advanced technologies in this field as well as the most rigorous laboratory and R&D tests.
The wide range of power available to us, in addition to the equipment that can be manufactured according to the customer’s needs, ranges from 25 kvar to 600 kvar per unit per capacitor, all of them with internal fuses and for a wide range of rated voltages.
The tolerance will always be between -5%/+10% according to IEC 60871-1.
|Three Phase||Single Phase|
|Type||AT…||AM… / AS…|
|Power output||25 – 500 kvar||25 – 600 kvar|
|Voltage rating||1,0 – 11,0 kV||1,0 – 24,0 kV|
|High system Voltage||7,2 – 12 kV||7,2 – 12 – 17,5 – 24 – 36 kV|
|Residual voltage and time||75V / 10 minutes|
|75V / 10 minutes|
|Impregnant||SAS-40E / M/DBT|
|SAS-40E / M/DBT|
|Internal connection||Star||Single Phase|
Basic Isulation Level (BIL) Table
|Maximum system voltage for capacitors conforming to the specification|
|Power frequency, test voltage kV. 50 Hz 1 min.||20||28||38||50||70|
|Impulse Level, 1,2kV / 50 μs||60||75||95||125||170|
|Creepage distance (mm)||140||190||300||435||600|
|Type of Capacitor|
Ambient air condiction por operation according to IEC: 60871
|AMBIENT AIR TEMPERATURE (Cº)|
|Symbol||Temperature maximum||Highest mean over any period of 24 hours||Highest mean over any period of 1 year|
As we have discussed earlier, internal fuse provides protection against total failure of capacito unit, case rupture and explosion. Therefore it is advisable to select capacitor units having internal fuse protection. Table below indicates the rating of capacitor units which are normally having internal fuses:
|Rated Voltage [kV]||Single Phase Capacitor Power units with internal Fuse|
|50 kvar||75 kvar||100 kvar||150 kvar||200 kvar||250 kvar||300 kvar||350 kvar||400 kvar||450 kvar||500 kvar||550 kvar||600 kvar|
Lifasa Capacitors conforms to:
- IEC 60871-1 & 2
- IEC 593
Routine or individual tests
The individual tests on the capacitors in our facilities in accordance with the strict recommendations of the IEC 60871 standard are as follows:
- Tightness test.
- Average capacity.
- Average capacitor losses.
- High Voltage Test between terminals.
- Discharge resistance (Capacitor discharge test).
- High voltage test at industrial frequency to check the dielectric insulation (between short circuit terminals and tank).