POWER FACTOR CORRECTION CAPACITORS
CAPACITOR BANKS, CONTROLLERS AND COMPONENTS

The capacitors and capacitor banks are used in the energy sector (power factor correction), green energy generation (wind and photo voltaic power plants), traction systems and induction heating equipment.

Under normal operating conditions, electrical equipment (electric motors, transformers, welding machines, fluorescent lamps, etc.) consumes not only active power from the power system, but also reactive power. The active power is directly related to the output that converts the electric energy into other types of energy that produces useful work (i.e. mechanical energy, thermal energy, etc.). Reactive power is necessary for the conversion of power through the electric or magnetic field for the operation of inductive electrical equipment (e.g. motors, transformers, etc.). Although reactive power does not perform useful work, consumers are billed for reactive power when it is supplied by their electricity provider. In an electrical system with substantial inductive loads, such as induction motors, consumers can reduce their electricity bills by supplying their own reactive power from capacitors. Apart from a reduction in electricity costs, installing capacitors has several other advantages which include improvement of cable, transformer and motor losses, voltage regulation and capacity reduction of current carrying distribution equipment.



POWER FACTOR CORRECTION CAPACITORS & COMPONENTS INFORMATION

Low Voltage Power Capacitors

Cylindrical MKP type capacitors designed for individual, group or central power factor correction in low-voltage networks. The MKP system consists of metallised polypropylene foil with self-healing properties and extremely low dielectric losses. Capacitors are filled either with inert gas (N2) for CSADG types or semi solid resin for CSADP types. The resin is non-toxic and ecologically friendly. All capacitors are available for voltages up to 800V and 50kVar, and are fitted with discharge resistors and over-pressure devices to safely disconnect failed capacitors from the network.

Three phase capacitors have three elements connected in delta. Capacitors are protected with overpressure disconnector, which ensures safe disconnection of the capacitor from the network in the event of overloading or at the end of its operation life. All the capacitors are equipped with built-in discharge resistors.

The case of the capacitor is protected against bursting by the overpressure disconnector. Its proper function is ensured only if the specifications and conditions (voltage, current, temperature, correct installation, maintenance) are observed. Failure to meet and/or exceed these conditions may result in bursting of the capacitor case or even explosion and subsequent fire.

Low Voltage Automatic Capacitor Banks

Constructed in mild steel cabinets with floor or wall mounting options. Designed to meet individual customer requirements, the banks are equipped with automatic PFC regulators, switching contactors, ZEZ Silko cylindrical capacitors (MKP capacitors, dry-type) and fuses. Main contractors are installed on all banks and consist of either three-phase circuit breakers or fused switches.

Low Voltage Detuned Reactors and Switching Contactors

Frequent use of power electronic devices with nonlinear loads leads to harmonic distortion in electrical system. This non-sinusoidal load causes an increase of effective current in power capacitors and other components of the system as well as the possibility of capacitor resonance with other inductive loads. Eventually, it may lead to problems or even failures in the installation. The solution is to use detuning (filter) reactors, which creates a series resonant circuit with power capacitors. This detuned system prevents the installation from resonance effect and also acts as a filter for higher harmonic content. It is usually recommended to use detuning reactors for the total voltage distortion THD-U higher than 3 %. Type CC capacitor contactors are suitable for switching low-inductive and low-loss capacitors in capacitor banks, without and with reactors. CC capacitor contactors are designed to meet capacitor duty applications. Contactors are fitted with a block of three early make auxiliary contacts in series with six damping resistors - 2 per phase. These auxiliary contacts limit peak current in the first stage of switching. Subsequently, the nominal current is transferred through main contacts which are switched in the next stage and the auxiliary contacts are switched-off at the same time. Contactors K3-..K are suitable for switching low-inductive and low loss capacitors in capacitor banks (IEC 70 and 831, VDE 0560) without and with reactors. Capacitor switching contactors are fitted with early make contacts and damping resistors, to reduce the value of making current < 70 x Ie. Capacitor switching contactors are protected against contact welding for a prospective making current of 200 x Ie. Fuse rating approx. 1,6 to 2,5 x Ie, type gL (gG).

Medium Voltage Capacitors

Designed for power factor correction and harmonic filtering in medium voltage networks. The ZEZ Silko capacitors use All Film technology, the dielectric is polypropylene foil impregnated with non-toxic, non-PCB environmentally friendly and biodegradable synthetic oil. Capacitor discharge is effectively achieved by internal discharge resistors that will discharge the capacitor voltage to 75Volt within 10 minutes or to 50Volt within 5 minutes. The capacitor cases and mounting brackets are manufactured from Stainless Steel that is polyurethane coated to ensure prolonged durability. The welded type porcelain bushings are available for a variety of pollution levels to cope with any operating environment. Complying with the requirements of IEC/EN 60871-1 and GOST 1282-88, the capacitors are supplied as temperature category -40/C, or for temperature category -40/D on request. The capacitors are available in Single and Three-Phase design for voltages up to 24kV and 1000kVar, and can be supplied with pressure sensors operating from 230V/50Hz supply voltage.

Medium Voltage Capacitor Banks

Capacitor banks type SCB and ACB are used for individual or central power factor correction in medium voltage power networks. The capacitor banks are constructed in mild steel cabinets according to customer specifications. Standard construction includes ZEZ Silko MV capacitors, three−phase units or single−phase units in star connection or, alternatively, single−phase units in double−star connection. Depending on customer requirements, the capacitor banks can be equipped with inrush current reactors and other protection and measuring elements consisting of unbalance detection relays, detuning reactors and current transformers. For complex technical solutions, automatic capacitor banks are equipped with automatic PFC regulation and vacuum contactors. The capacitor banks are available for voltages up to 36kV and power ratings up to 10MVAr.

The ZEZ Silko capacitor bank type SCA is used for individual or central power factor correction in medium voltage power networks. The capacitor banks are constructed on steel frames according to customer specifications. Standard construction includes ZEZ Silko MV capacitors, three−phase units or single−phase units in star connection or, alternatively, single−phase units in double−star connection. Depending on customer requirements, the capacitor banks can be equipped with inrush current reactors and other protection and measuring elements consisting of unbalance detection relays, detuning reactors and current transformers. The capacitor banks are available for voltages up to 132kV with power ratings on request.

Medium Voltage Surge Capacitors

Surge capacitors are used to limit the surge wave shape to prevent damage to the insulation of MV motors, generators and transformers. The ZEZ Silko surge capacitors are generally used in combination with surge arresters to limit the surge wave shape and magnitude. The capacitors use All Film technology, the dielectric is polypropylene foil impregnated with non-toxic, non-PCB environmentally friendly and biodegradable synthetic oil. Capacitor discharge is effectively achieved by internal discharge resistors that will discharge the capacitor voltage to 75Volt within 10 minutes. The capacitor cases and mounting brackets are manufactured from Stainless Steel that is polyurethane coated to ensure prolonged durability. The welded type porcelain bushings are available a variety of pollution levels to cope with any operating environment. Complying with the requirements of IEC/EN 60871-1, the capacitors are supplied standard as temperature category -25/C capacitors for voltages up to 36kV.

Medium Voltage Detuned Reactors and Inrush Current Reactors
The reactors have high linearity, low losses and minimal noise. Inductance is fixed to the exact value with tolerance of –1/+3%. The ZEZ Silko reactors are designed for capacitors at 7200 V (grid 6000 V) and 12000 V (grid 10000 V), 50 Hz and tuned to a resonance frequency of 189 Hz. Reactors are wound on a Fe core with insulation Class B. Reactors for other voltage, frequency and power are available on request. Inrush current reactors protect the capacitors from very high peak inrush currents during switching operations. Available for max rated voltage 40 kV, max rated current 250 A. Standard rated voltage 7,2 and 12 kV with Insulation class “F

DC Wave Filter and Surge Capacitors (Transnet Specifications)
Rated at 3,4kVDC, the 10µF , 20µF and 50µF the ZEZ Silko wave filter capacitors are used for harmonic filtering in 3kVDC traction substations. The capacitors are used with resonant shunts to reduce the magnitude of the 6th, 12th, 18th and 24th harmonics at the busbar of the 3kVDC rectifier traction sub-station. The 3kVDC/4µF ZEZ Silko capacitor is used to protect Transnet Freight Rail electrical equipment against surges caused by lightning. The ZEZ Silko capacitors use All Film technology, the dielectric is polypropylene foil impregnated with non-toxic, non-PCB environmentally friendly and biodegradable synthetic oil. Capacitor discharge is effectively achieved by internal discharge resistors that will discharge the capacitor voltage to 50V within 5 minutes. The capacitor cases and mounting brackets are manufactured from Stainless Steel that is polyurethane coated to ensure prolonged durability. The wave filter capacitors are supplied as temperature category -10/D, and the surge absorber capacitor as temperature category -40/D. The wave filter and surge absorber capacitors comply with the Transnet Technology Management specifications BBB3139 and CEE0115 respectively.
Induction Heating Capacitors

Water cooled capacitors are special power capacitors designed for tuning induction furnace and heating circuits. The individual production lines listed in the catalogue cover a wide range of capacitances, powers and frequencies in several different designs. Adjustment of electrical and mechanical parameters according to customer requirements - from simple changes to complete processing of the entire capacitor.

  • Voltage: up to 3000 V
  • Capacitance: up to 1000 µF
  • Power: up to 8000 kvar
  • Frequency: up to 200 kHz

Air Cooled Capacitors

Air cooled capacitors are special power capacitors up to 800 V designed for tuning the circuits of induction furnaces and low frequency heaters 50/60 Hz. Thanks to the technology used, big capacitances in the unit can be achieved at lower voltages compared to water-cooled capacitors.

  • Voltage: up to 800 V
  • Capacitance: up to 4400 µF
  • Power: up to 360 kvar
  • Frequency: 50/60 Hz

COAX type capacitors

Special power capacitors designed for tuning induction furnace and heating circuits, are also used in generator circuits. Thanks to the coaxial design, capacitors of this type are suitable for use at higher frequencies. Due to the compact design, the capacity required for the device can be assembled from the individual units.

  • Voltage: up to 2000 V
  • Capacitance: up to 12 µF
  • Power: up to 1000 kvar
  • Frequency: up to 400 kHz
Capacitors for Power Electronics

AC Filter Capacitors

AC filter capacitors are used in converters and inverters. They are used in equipment for traction vehicles, wind and photovoltaic power plants. Other applications can also include the use in industrial drive inverters. They are generally used in an input filter or an output filter.

  • Voltage: up to 2 500 VAC
  • Capacitance: up to 600 µF

DC Link Cylindrical Capacitors

DC Link capacitors are used in converters, inverters and rectifiers. They are used in equipment for traction vehicles, wind and photovoltaic power plants. Other applications can also include the use in industrial drive inverters. They are generally used in an input filter or a DC link filter.

  • Voltage: up to 3 000 VDC
  • Capacitance: up to 4 500 µF

DC Link Rectangular Capacitors

DC Link capacitors are used in converters, inverters and rectifiers. They are used in traction vehicle equipment (including EV and HEV) or inverters for large industrial drives. They are generally used in an input filter or a DC link filter.

  • Voltage: up to 6 000 VDC
  • Capacitance: up to 24 000 µF

Energy Storage Capacitors

Impulse or Energy storage capacitors are used in laboratory equipment, medical devices, power lasers or welding equipment.

  • Voltage: up to 100 kV DC
  • Energy: up to 120 kJ

Snubber Capacitors

Snubber capacitors are used as protection for power semiconductors. The design of the capacitor guarantees the achievement of very low values of self-inductance and series resistance.

  • Voltage: up to 12 000 VDC
  • Capacitance: 60 µF
Power Factor Correction Controllers
Controllers Super PFR, PFR6 & PFR12, MULTI PFR6 and MULTI PFR12 monitor the power system status and accurately take decisions on the connection or disconnection of compensation stages in order to reach the pre-set power factor. The controller’s microprocessor records system voltage and current consumption of the entire operation via instrument transformer inputs and uses these to calculate the relationship between active power and reactive power in the power system. The regulator calculates the basic harmonic factor of the active and reactive currents using the FFT algorithm. Thus, precise measurement and control is provided even if the current waveform is distorted by higher harmonic components.
Vacuum Contactors and Instrument Transformers
Vacuum contactors are specifically designed for industrial applications where large numbers of switching operations are required. The ZEZ Silko vacuum contactor is optimal for switching capacitor banks from 3,3kV up 6,6 kV. The current and voltage transformers are intended for measuring and protection of high voltage distribution systems of the indoor as well as outdoor type. These instruments transformers are intended for the voltage system from 3,6kV up to 40,5kV. The transformer comply with the requirements of IEC 60044-1, IEC 60044-2, GOST 1983-89 and DIN 42600/1983.
Measurement and Control
AFQm Active Filters

Wall-mounted multi-level AFQm active filters are the most comprehensive solution to power quality problems in three-phase industrial or commercial networks caused by the presence of harmonics and reactive power consumption. The following characteristics and functions were implemented: load capacity 30 A, 60 A and 100 A

 

  • The wall cabinet is easy to install due to its small dimensions
  • Suitable for installations with 3 wires (model 3W) or 4 wires (model 4W)
  • Large range of voltage levels and frequencies 50/60 Hz
  • Reduction of harmonic currents up to the fiftieth harmonic (2500 Hz)
  • Selection of harmonic frequencies to be filtered for maximum filter efficiency
  • Inductive and capacitive power factor correction
  • Phase current balancing, N-conductor load reduction (model 4W)
  • If higher filtering capacities are required, up to 100 filters can be connected in parallel (filters must have the same number of connecting wires - 3W or 4W)
Network Power Analysers

Get information on a large number of electrical variables in real time to achieve maximum energy efficiency of your installations. CIRCUTOR energy analysers are suitable for any type of installation and can be mounted in a panel or DIN rail in both high-voltage and low-voltage installations. The offer also includes a unit with an energy accuracy of 0.5%, which measures up to the 50th harmonic component, includes a communication system and monitors more than 700 variables up to the most basic unit, which measures the main electrical parameters and does not include the communication system.

Measuring Current Transformers

Current measuring transformers are used to convert a high rated current so that it can be accurately measured by other equipment such as an analysers, regulators and the like. The offer includes classic plug-in measuring transformers, transformers with a detachable core, shunts or, for example, special transformers of the MC series.

Medium Voltage Surge Capacitors
Surge capacitors are used to limit the surge wave shape to prevent damage to the insulation of MV motors, generators and transformers. The ZEZ Silko surge capacitors are generally used in combination with surge arresters to limit the surge wave shape and magnitude. The capacitors use All Film technology, the dielectric is polypropylene foil impregnated with non-toxic, non-PCB environmentally friendly and biodegradable synthetic oil. Capacitor discharge is effectively achieved by internal discharge resistors that will discharge the capacitor voltage to 75Volt within 10 minutes. The capacitor cases and mounting brackets are manufactured from Stainless Steel that is polyurethane coated to ensure prolonged durability. The welded type porcelain bushings are available a variety of pollution levels to cope with any operating environment. Complying with the requirements of IEC/EN 60871-1, the capacitors are supplied standard as temperature category -25/C capacitors for voltages up to 36kV.