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Basics of Power Factor Correction

Under normal operating conditions certain electrical loads (e.g. induction motors, welding equipment, arc furnaces and fluorescent lighting) draw not only active power from the supply, but also inductive reactive power (kvar). This reactive power is necessary for the equipment to operate correctly but could be interpreted as an undesirable burden on the supply. The power factor of a load is defined as the ratio of active power to apparent power, i.e. kW, kVA and is referred to as cosφ. The closer cosφ is to unity, the less reactive power is drawn from the supply:

If cosφ = 1 the transmission of 500kW in a 400V three phase mains requires a current of 722 A. The transmission of the same effective power at a cosφ= 0.6 would require a far higher current, namely 1203 A. Accordingly, distribution and transmission equipment as well as feeding transformers have to be derated for this higher load. Furthermore their useful life may also be decreased.

For systems with a low power factor the transmission of electric power in accordance with existing standards results in higher expenses both for the supply distribution companies and the consumer.

Another reason for higher costs are the losses incurred via heat dissipation in the cables caused by the overall current of the system as well as via the windings of both transformers and generators. If we assume for our above example that with cos φ= 1 the power dissipated would amount to about 10kW, then a power factor of 0.6 would result in a 180% increase in the overall dissipation i.e. 28kW.

In general terms, as the power factor of a three phase system decreases, the current rises. The heat dissipation in the system rises proportionately by a factor equivalent to the square of the current rise.

This is the main reason why Electricity Supply Companies in modern economies demand reduction of the reactive load in their networks via improvement of the power factor. In most cases, special reactive current tariffs penalize consumers for poor power factor.


  • A reduction in the overall cost of electricity can be achieved by improving the power factor to a more economic level.
  • The supply will be able to support additional load which may be of benefit for an expanding company.
  • Reducing the load on distribution network components by power factor improvement will result in an extension of their useful life.

Types of Power Factor Correction

A capacitive reactive power resulting from the connection of a correctly sized capacitor can compensate for the inductive reactive power required by the electrical load. This ensures a reduction in the reactive power drawn from the supply and is called Power Factor Correction.

Most common methods of power factor correction are:

SINGLE OR FIXED PFC, compensating for the reactive power of individual inductive loads at the point of connection so reducing the load in the connecting cables (typical for single, permanently operated loads with a constant power).

GROUP PFC - connecting one fixed capacitor to a group of simultaneously operated inductive loads (e.g. group of motors, discharge lamps)

BULK PFC, typical for large electrical systems with fluctuating load where it is common to connect a number of capacitors to a main power distribution station or substation. The capacitors are controlled by a microprocessor based relay which continuously monitors the reactive power demand on the supply. The relay connects or disconnects the capacitors to compensate for the actual reactive power of the total load and to reduce the overall demand on the supply.

A typical power factor correction system would incorporate a number of capacitor sections determined by the characteristics and the reactive power requirements of the installation under consideration. Sections of 12.5 kvar, 25 kvar, and 50kvar are usually employed. Larger stages (e.g.100kvar and above) are achieved by cascading a number of smaller sections. This has the beneficial effect of reducing fluctuations in the mains caused by the inrush currents to the capacitors and minimizes supply disturbances. Where harmonic distortion is of concern, appropriate systems are supplied incorporating detuning reactors.

Calculation of Required Capacitor Power

The reactive power which is necessary to achieve a desired power factor is calculated by the following formula:

QC = P • F
QC - reactive power of the required correcting capacitor
P - active power of the load to be corrected
F - conversion factor acc. to chart 1

Original Power Factor Multiplication Factor (tanφ1 - tanφ2) for a target power factor
COSφ1 tanφ2 COSφ2                  
    0.70 0.75 0.80 0.85 0.90 0.92 0.94 0.96 0.98 1.00
0.20 4.9 3.88 4.02 4.15 4.28 4.42 4.47 4.54 4.61 4.7 4.9
0.25 3.87 2.85 2.99 3.12 3.25 3.39 3.45 3.510 3.58 3.670 3.87
0.30 3.18 2.160 2.3 2.430 2.560 2.7 2.75 2.82 2.89 2.98 3.180
0.35 2.68 1.66 1.8 1.93 2.06 2.19 2.250 2.31 2.39 2.47 2.68
0.40 2.29 1.27 1.41 1.54 1.67 1.81 1.87 1.93 2.000 2.09 2.29
0.45 1.99 0.96 1.1 1.24 1.37 1.500 1.56 1.62 1.69 1.78 1.99
0.50 1.73 0.71 0.85 0.98 1.11 1.25 1.31 1.37 1.440 1.53 1.73
0.55 1.52 0.5 0.64 0.77 0.9 1.03 1.09 1.16 1.23 1.32 1.52
0.60 1.33 0.31 0.45 0.58 0.71 0.85 0.91 0.97 1.04 1.130 1.33
0.65 1.17 0.15 0.29 0.42 0.55 0.69 0.74 0.81 0.88 0.97 1.17
0.70   1.020 0.14 0.27 0.4 0.54 0.59 0.66 0.73 0.82 1.020
0.75     0.88 0.13 0.26 0.4 0.46 0.52 0.59 0.68 0.88
0.80       0.75 0.13 0.27 0.32 0.39 0.46 0.55 0.75
0.85         0.62 0.14 0.19 0.26 0.33 0.42 0.62
0.90           0.48 0.06 0.33 0.19 0.28 0.48
0.95                 0.04 0.13 0.33

a.Consumption of active energy: ………EW = 300000kWh
b.Consumption of reactive energy: ………EB = 400000 kvarh
c.Number of working hours: …………t = 600 h

Resulting average active power: P = = 500kW

Calculation of the original power factor cosφ1:


For the improvement of the power factor from 0.6 to 0.9 we read the factor 0.849 from the chart above.

The required capacitor power is: QC = 500kW•0.849 = 425 kvar

Influence of Harmonics, Harmonic Filtering

Developments in modern semiconductor technology have led to a significant increase in the number of thyristor - and inverter-fed loads.

Unfortunately these non-linear loads have undesirable effects on the incoming AC supply, drawing appreciable inductive reactive power and non-sine-wave current. The supply system needs to be kept free of this harmonic distortion to prevent equipment malfunction.

A typical inverter current is composed of a mixture of sinewave currents; a fundamental component at the supply frequency and a number of harmonics whose frequencies are integer multiples of the line frequency (in three phase mains most of all the 5th, 7th, and 11th harmonic). The harmonics lead to a higher capacitor current, because the reactive resistance of a capacitor reduces with rising frequency.

The rising capacitor current can be accommodated by constructional improvements in the manufacture of the capacitor. However a resonating circuit between the power factor correction capacitors, the inductance of the feeding transformer and the mains may occur. IF the frequency of such a resonating circuit is close enough to a harmonic frequency, the resulting circuit amplifies the oscillation and leads to immense over-currents and over-voltages.

Harmonic distortion of an AC supply can result in any or all of the following:

  • Premature failure of capacitors.
  • Nuisance tripping of circuit breakers and other protective devises.
  • Failure or maloperation of computers, motor drives, lighting circuits and other sensitive loads.

The installation of detuned (reactor-connected) capacitors - see pic. 1 - is designed to force the resonant frequency of the network below the frequency of the lowest harmonic present, thereby ensuring no resonant circuit and, by implication, no amplification of harmonic currents. Such an installation also has a partial filtering effect, reducing the level of voltage distortion on the supply, and is recommended for all cases where the share of harmonic-generating loads is more than 20% of the overall load to be compensated. The resonance frequency of a detuned capacitor is always below the frequency of the fifth harmonic.

A close-tuned filter circuit however is tuned to a certain harmonic frequency and presents a very low impedance to the individual harmonic current, diverting the majority of the current into the filter bank rather than the supply.


This description and our product range both focus on single capacitors and reactive power compensation systems in the power range from 50 to approx. 6.000 kvar, because the greatest deficit in risk-awareness is present here. In practice, they are often just "parked" somewhere since the dimensions and prices of such equipment are relatively small and they should be close to the load. Protection devices are then often neglected in comparison to larger systems, because the costs appear to be unreasonably high.

It is a fact that the protection systems necessary for the reliability operation of a small reactive power compensation system, e.g. 300 kvar, require the same protection relay and a similarly expensive current transformer as a 10 MVAR system. IF the total power is divided into 3 or 6 units, even higher costs are incurred. Disparities of up to 80% for the protection component then occur, compared to 5% fro larger systems.

Serious mistakes are often made especially in the reactive power compensation of small installations, which lead to equipment damage and environmental incompatibility. This unsatisfactory situation was the starting point for the development of a new concept that offers an acceptable relationship between protection costs and total costs, while reducing the ecological risk.

Operational Stress of Allfilm Medium Voltage Capacitors

Capacitors operate at full power immediately after switching. No-load or low-load periods do not exist. The design is made under economical constraints with high electrical field strengths up to 75 kV/mm and a finite service life, which can be dependent on many influencing factors, and is estimated from statistical data. There are many effects that cannot be detected during durability tests.

Summarizing, it can be said that modern power capacitors are very reliable and failure rates greater than 0.2% per year are very rare. However, it must be considered that must higher failure rates occur from early failures, manufacturing faults, dimensioning errors, incorrect application or overload.

The effects of such failures must be assessed carefully by means of a risk analysis that also includes the ecological risk, due to the high short-circuit power present in medium voltage installations.

Objective of Capacitor Protection Techniques

The reduction of damage to the environment is the most important criterion for capacitors, while preventative protection against permanent damage is the prime concern with motors, transformers, inverters, lines, cables and similar components.

Breakdown Behavior of Allfilm Medium Voltage Capacitors

Breakdown of the dielectric is the prime cause of failure. Only this breakdown and the resulting consequential effects are considered here.

Every breakdown of a single winding element in a capacitor with several internal serial winding circuits leads to a change of the internal voltage distribution, irrespective of whether this winding is fused individually or whether it is fuse-less design. This leads inevitably to higher voltage stress in the remaining part of the winding element. Accelerated ageing accompanies the increased voltage stress, which leads to further winding breakdowns.

Considerable damage to the environment of the capacitor must be expected if the breakdown process is uncontrolled, i.e. operation is continued until an over-current, earth or short-circuit trip responds.

This means that, when the maximum permitted energy input into the capacitor casing is exceeded (violation of the typical current-time destruction limit), it can in the worst case tear open, and the contents of the casing be rejected. A considerable shock wave, with ignition of the oil spray and the solid inflammable content, are conceivable further consequences.

Protection for medium voltage capacitors normally means the mini-misation of effects of already existing, irreversible capacitor damage to the direct neighborhood. This occurs in the knowledge that Allfilm capacitors contain a large proportion of ecologically critical, flammable, solid and fluid organic materials, which pose a considerable hazard potential.

3-Phase Medium Voltage Capacitors

These capacitors are frequently built without internal fuses, due to their unusually low power and three-phase design. Such a capacitor exhibits a group short-circuit after a winding breakdown.

Depending upon the number of internal serial circuits, the capacitance and voltage stress in the affected branch increase by the factor n/n-1.

The current increases correspondingly. This is thermally barely noticeable due to the low capacitor losses and further short-circuits can occur, especially if the fault remains unnoticed for a long period.

Since remaining windings can still survive at up to twice the rated voltage for minutes or even hours, the effects on fuses and feeders under the influence of twice the rated current are to be taken into account.

Gas formation need not be expected during this overload phase, since the film layers weld together solidly at the breakdown position and can carry increased current for a long period. An internal pressure build-up does not occur during this period.

Pressure monitors are ineffective in Allfilm medium voltage capacitors.


Various concepts for the protection and switching of medium voltage capacitors are known from practice. The five most usual will be discussed here.

Current overload caused by a group short-circuit in the capacitor, or also at resonance with network harmonics, cause a danger that the short-circuit protection fuse trips in the over-current range if the current rating is too low. The arc quenching capability of the fuses can be overtaxed due to the capacitive load. Reverse sparking occurs with very high intensities and ultimately leads to an open arc at the fuse contacts, and to a phase short-circuit at the installation position of the fuse.

Choice of Nominal Fuse Current

Fuses must be chosen for at least 1.6 times the rated capacitor current to withstand the switching current. Since Allfilm capacitors can remain connected to the mains in fault situations (failure of serial groups) for a long period with up to double the nominal capacity, fuses should be rated for at least 2 x lN. The risk that fuses rupture due to over-current, but do not quench the arcing is avoided by this method.

If fuse rating of approx. 200A are exceeded, then an additional problem occurs: In the case of a short-circuit, the fuse throughput energy becomes greater than the energy absorption capacity of the capacitor enclosure.

Selection of the Rated Voltage for Capacitor Fuses

Current limiting fuses have an excellent interpretation behavior during short-circuits, but are usually not able to interrupt capacitive currents at overload. A peak voltage with twice the amplitude occurs at the gap due to the charged capacity, which can result in arcing-back with even higher voltages. One should therefore always employ h.v.h.b.c. general purpose fuses with the next higher nominal voltage than the actual mains voltage.

If no protection system for early fault detection, such as asymmetry protection or phase current comparison protection is employed additionally, then the concept is not safe.

As a rule, circuit breakers are unsuitable for the disconnection of capacitors with an internal short-circuit, since they do not possess a current-limiting interruption characteristic. The throughput energy before isolation is always much larger than a capacitor enclosure can withstand.

Satisfactory capacitor protection is not possible due to the layout of the fuse and motor protection for the total current.

When operated with an undetected group short-circuit in the capacitor, a considerable overvoltage will arise at the motor during the shutdown phase after disconnection from the supply. As a result, the already overloaded residual capacitance may flash over. The next switch-on is then made onto a short-circuited capacitor, which may cause the capacitor to burst and the motor insulation to be damaged.

Fixed compensation systems cannot be satisfactorily protected without additional sensitive protection systems. At least separate fuses matched to the capacitors are necessary. Better would be the application of a highly sensitive additional protection system that trips already at a low fault level.

Load unbalance protection circuits detect the circulating current in the neutral branch of a bridge circuit or between two star points of a double circuit, that occurs after the breakdown of a winding or a winding group.

Even the breakdown of the first winding element in a small capacitor systems can be detected reliability and be used to trip the associated switch. The other switching functions of this switch are irrelevant, so far as the protection tripping disconnects the capacitor immediately at a low fault level, or in the case of multi-step systems, after a previous alarm signal.

Reliable protection against consequential damage is achieved with the correct setting of a predefined switch-off threshold at a low fault level.

Remaining problem:
High costs and effort for ecological protection and disposal.

Similar to an asymmetry protection scheme; can avoid consequential damage from premature tripping. Network asymmetries or starting asymmetries can lead to erroneous tripping more easily than with variant 4. The sensitivity which may be achieved with phase comparison protection is lower than with an asymmetry protection circuit.

Apart from that, the problems of variant 4 remain.

Course of Damage at Capacitors with Winding Fuses:

Depending on type, winding fuses are able to interrupt currents at network frequency, with current limitation, at mains voltages of up to several kV. At higher voltages and with several internal series connections, the voltage at the remaining windings continues to increase with decreasing number of paralleled winding elements, until the interruption ability of the winding fuse is overtaxed. The damage arising here can lead to the destruction of the insulation between the phases or towards the enclosure.

The consequences are depending on the through-put energy of the associated over-current protection and more or less identical to those occurring at capacitors without fuses. Capacitors can be considered partially safe if they contain no more than two internally fused, series-connected winding groups between the phases, e.g. star-connected 3.6 kV capacitors or single-phase capacitors up to 3.63 kV in furnace systems.

During the development of a highly advanced state of fault, the risk rises that not only winding breakdowns occur, but parts of the internal insulation get damaged, too which may lead to a short-circuit at a high fault level. The risk of consequential damage is significantly higher than if asymmetry protection systems were used.

Basic Rule:

The most important criterion for a timely disconnection without consequential damage is early detection and, if possible, rapid disconnection of capacitors groups after the failure of windings or winding groups. This ensures that fuses do not trip due to increased current and that rapid short-circuit trips do not occur, both of which can have the very serious consequences described above. This applies especially to three-phase capacitors.

Other criteria must be taken into account in the case of large compensation powers, which shall not be discussed here. A network short-circuit is improbable due to multiple external series circuits.

Correct Handling of Fault Tripping

One repeatedly observes that fault trips are rest or recluse attempts made by operating staff, without the cause of the trip being clarified and cleared.

Enormous consequential damage is observed and documented from such incorrect conduct.


Design and Characteristics

The MSD technology is based on the logical development of proven self-healing technology for low-voltage power capacitors. It also permits the economic manufacture of medium voltage capacitors without employing inflammable and environmentally critical fluid oil fillings.

The actual active capacitor element consists of a large number of high-quality, self-healing round MKP elements, which are wired to each other and installed in a stainless steel enclosure.

OUR MSD Capacitors are filled with solid materials, i.e. dry, instead of combustible liquid as with Allfilm medium voltage capacitors.

High quality insulation between the active elements and the enclosure is achieved using a special process, which is designed and tested to suit the requirements for the nominal insulation voltage of the capacitor. This special insulation is of crucial importance for the safe operation of the internal pressure monitor: self-healing capacitors are not (yet) covered by current standards for medium voltage capacitors, such as IEC 871, however, our MSD series fulfils all electrical and safety requirements of these standards. It has to be noted that the MSD capacitors - like any self healing capacitor - do not produce short circuits and can therefore not be disconnected from the system by internal or external blow-out fuses. This task is performed by integrated over-pressure switches as described in the standards applicable to capacitors for power electronics and for inductive heating. (VDE-EN 61071 and VDE-EN 60110).

Benefits of the New MSD Technology

  • Short-circuit currents are not possible due to the high-resistance fault characteristic of the self-healing dielectric. Special, short-circuit current limiting capacitor fuses are not necessary. Functional switching devices are sufficient for tripping.
  • The costs of the monitoring circuit are very low. It is sufficient to control the tripping function of the switch via the normally closed contact of the pressure monitor.
  • Every enclosure is monitored separately. Any number of individual capacitors can be grouped together for protection purposes.
  • As a consequence of the different partial failure mode of MSD capacitors compared to that of Allfilm capacitors, the possibility of current imbalance in the three phases can be almost totally ruled out. Hence monitoring of the star point is unnecessary which leads to further reduction of installation cost.
  • Oil Pumps are unnecessary due to the dry design; no oil that could pollute the local environment. No disposal problems at the end of useful service live.
  • Reliability during applications in de-tuned and tuned filters and double filters by
    • Long term stability of capacitance
    • Significantly smaller temperature sensitivity of capacitance with values of approx. -2.5 x 10-4 compared to a 60% higher value for Allfilm dielectrics
    • Very small capacitance tolerances up to ±2.5%.

Economic Viability

The pure capacitor manufacturing costs are slightly higher than former Allfilm capacitors as a result of the employment of especially high quality materials and a special production process.

If the total system costs including electrical protection systems such as asymmetry protection, fire protection and environmental protection measures are also considered, then significant cost benefits are achieved in the small to medium power range. The new technology offers decisive advantages in the range from 50 to approx 6000 kvar. Larger powers are also generally possible in the voltage range up to 12kV.

Oil-filled capacitors are not permitted at locations with special fire risk, e.g. in mines, in protected water catchment areas or drinking water pump stations, so that other alternatives are often unavailable.


Fixed motor and transformer compensation, automatic capacitor banks, detuned and tuned filter circuits, in double filters, audio frequency links and other applications in critical areas for application in the 1.9 to 12kV range.


Rated Voltage UN

Root mean square of the max. permissible value of sinusoidal AC voltage in continuous operation.

The rated voltage of the capacitors indicated in the data charts must not be exceeded even in cases of malfunction. Bear in mind that capacitors in detuned equipment are exposed to a higher voltage than that of the rated mains voltage; this is caused by the connection of detuning reactor and capacitor in series. Consequently, capacitors used with reactors must have a voltage rating higher than that of the regular mains voltage.

Calculation Voltage UB

Voltage used for the calculation of the capacitor. Usually the rated mains voltage plus 5% overvoltage.

The voltage at a detuned capacitor's terminals can be calculated as follows:

UN = Rated mains voltage
UC = Capacitor voltage
p = Detuning factor

Test Voltage Between Terminals UBB

Routine test of all capacitors conducted at room temperature, prior to delivery. A further test with 80% of the test voltage stated in the data sheet may be carried out once at the user's location.

Insulation Level (BIL)

The first value describes the routine test of all capacitors between short-circuited terminals and case, conducted at room temperature. May be repeated at the user's location.

The second value refers to the lighting withstand voltage, tested in a special type test.

Rated Power QC

Reactive power resulting from the ratings of capacitance, frequency, and voltage.

LC outputQLC

Real output of the LC-circuit of capacitor and detuning reactor at calculation voltage UB.

Our MSD capacitors have been designed foe detuned circuits with adjusted rating at the detuning factor stated in the data sheets.

Current Rating lN

RMS value of the current at rated voltage and frequency, excluding harmonic distortion, switching transients, and capacitance tolerance.

Maximum RMS Current Rating lMAX

Maximum rms value of permissible current in continuous operation. All capacitors are rated 1.5 x lN, allowing for the current rise from permissible voltage and capacitance tolerances as well as harmonic distortion. The exact value for each capacitor can be found in the data charts. Higher rms values than stated in the data charts require adjustments in construction and are available on request.

Continuous currents that exceed these values will lead to a build-up of heat in the capacitor and - as a result - reduced lifetime or premature failure. Permanent excess current may even result in failure of capacitor's safety mechanisms, i.e. bursting or fire.

Care must be taken not to exceed the maximum voltage and current ratings when installing capacitors in close-tuned or detuned equipment (see data sheets for maximum ratings). The thermal monitoring of reactors, or the use of overcurrent protection relays in the capacitor circuit is recommended to protect against overloads.

Pulse Current Strength lS

Depending on construction and voltage rating, the design of our capacitors permits short term inrush currents of 100…400 x lN as standard. However, when switching capacitors in automatic capacitor banks without detuning reactors, higher loads are very often the case. This may have a negative effect on the operational life, especially of capacitors which are frequently connected and disconnected (e.g. primary stages).

We therefore strongly recommend the use of adequate devices for limitation of the peak inrush currents.

Temperature Category

The average useful life of a capacitor depends very much on the ambient temperatures it is operated at. The permissible operating temperatures are defined by the temperature class stated on label which contains the lower limit temperature (-40°C for all ELECTRONICON power capacitors) and a letter, which describes the values of the upper limit temperatures.


Safe operation of the capacitors can be expected only if all electrical and thermal specifications as stated on the label, in the data sheets or catalogues and the following instructions are strictly observed.

ELECTRONICON does not accept responsibility for whatever damage may arise out of a non-observance.

Caution: When touching or wasting capacitors, please consider that even days and weeks these capacitors may still be charged with high voltages!

Mounting Position

Our dry-type MSD-capacitors can be mounted in any position without restrictions.

Mounting Location/Cooling

The useful life of a capacitor may be reduced dramatically if exposed to excessive heat. Typically an increase in the ambient temperature of 7oC will halve the expected life of the capacitor.

The permitted temperature category of the capacitor (B, C or D) is stated on the label. If extenuating circumstances give cause for doubt, special tests should be conducted to ensure that the permitted maximum ambient temperature of the capacitor is not exceeded. It should be noted that the internal heat balance of large capacitors is only reached after a couple of hours.

Temperature Category Ambient Temperature Limits
  Maximum Max. Average over 24hrs Max. Average over 365 days
B 45°C 35oC 25°C
C 50°C 40°C 30°C
D 55°C 45°C 35°C

To avoid overheating the capacitors must be allowed to cool unhindered and should be shielded from external heat sources. We recommend forced ventilation for all applications with detuning reactors. Give at least 50mm clearance between the capacitors for natural or forced ventilation.

Do not place the capacitors directly above or next to heat sources such as detuning or tuning reactors, bus bars, etc.

Vibration Stress According to DIN IEC 68-2-6

Thanks to the solid resin filling, the internal construction is much more resistant against shock and vibration than in conventional oil-filled capacitors.

All capacitors can be fixed sufficiently using the mounting brackets at the can. Please consult us for details of permitted vibration stress for the fixation of the case.


Fuses and cross section of the leads shall be sized for at least 1.5 times of the rated capacitor current (lN).

Fixing Torque

The permitted torque of the M12 terminal studs is 10Nm. It must not be exceeded. The test values specified by IEC must be guaranteed as a minimum value.

  • The hermetic sealing of the capacitors is extremely important for a long operating life and for the correct functioning of the overpressure switch. Please pay special attention not to damage the insulators and the pressure switch.


Capacitors should be discharged to <10% of the rated voltage prior to being re-energized. For this purpose, special discharge resistors have been integrated inside the capacitors. Standard IEC 871 requires a discharge to 75V or less within 10 minutes. Note that special applications shorter discharge cycles may be required.


Capacitors with a metal case must be earthed at the mounting brackets or by means of the designated earthing stud on top of the case.

Environment Hazards, Disposal

Our capacitors do not contain PCB, solvents, or any other toxic or banned materials. They do not contain hazardous substances acc. to <<Chemische Verbotsverordnung>> (based on European guidelines 2003/53/EG and 76/769/EWG), <<Gefahrstoffverordnung>>(GefStoffV) and <<Bedarfsgegenstaendeverordnung (BedGgstV)>>.

Not classified as <<dangerous goods>> acc. to transit rules. The capacitors do not have to be marked under the Regulations for Hazardous Goods. They are rated WGK 0 (water risk category 0 <<no general threat to water>>).

The filling material contains a polyurethane mixture. A data sheet about the filling resin can be provided by the manufacturer on request.

No danger for health if applied properly.

We recommend disposing of the capacitors through professional recycling centers for electric/electronic waste.

The capacitors can be disposed of as follows:

  • Disposal acc. to European Waste Catalogue 160205 (capacitors filled with resin).
  • Hardened filling materials: acc. to EWC 080404 (<<Hardened adhesives and sealants>>).

Consult your national rules and restrictions for waste and disposal.

Caution: When touching or wasting capacitors with activated pressure switch, please consider that even after days and weeks these capacitors may still be charged with high voltages! Never open the capacitors!

Protection Against Overvoltages and Short Circuits: Self-Healing Dielectric

All dielectric structures used in our power capacitors are "self-healing": In the event of a voltage breakdown the metal layers around the breakdown channel are evaporated by the temperature of the electric arc that forms between the electrodes. They are removed within a few microseconds and pushed apart by the pressure generated in the centre of the breakdown spot. An insulation area is formed which is relatively resistive and voltage proof for all operating requirements of the capacitor. The capacitor remains fully functional during and after the breakdown.

For voltages within the permitted testing and operating limits the capacitors are short-circuit-and overvoltage-proof.

They are also proof against external short circuits as far as the resulting surge discharges do not exceed the specified surge current limits.

Protection Against Accidental Contact

MSD-capacitors are not provided with protection against accidental contact as standard. There are mounting brackets at the upper side of the case which will allow to fix a protective cover.

All capacitors are checked by routine test (voltage test between shorted terminations and case) in accordance with their rated insulation level. Accessible capacitors must be earthed at the earthing stud or one of the mounting brackets.

Protection Against Overload and Failure at the End of Useful Service Life

In the event of overvoltage or thermal overload or ageing at the end of the capacitor's useful service life, an increasing number of self-healing breakdowns may cause rising pressure inside the capacitor. To prevent it from bursting, the capacitor is fitted with an obligatory overpressure switch (opener). It enables external monitoring and - if necessary-disconnection of the capacitors through external devices. It has to be noted that this safety system can act properly only within the permitted limits of loads and overloads.


Capacitors consist manly of polypropylene (up to 90%), i.e. their energy content is relatively high. They may rupture and ignite as a result of internal faults or external overload (e.g. temperature, overvoltage, harmonic distortion). It must therefore be ensured, by appropriate measures, that they do not form any hazard to their environment in the event of failure or malfunction of the safety mechanism.

FIRE LOAD: appox. 40MJ/kg

EXTINGUISH WITH: dry extinguisher CO2, foam


Internal Connection …………Y Overpressure switch ………opener 5A/250V AC
Routine test voltage …………AC 2.15 x UN Ambient conditions ………indoor
Inrush current ………………max. 100 x IN Height a.s.l. (standard) ……2000m
Discharge resistor……………inside (75V/<10min) Creepage distances ………190mm
Power dissipation losses ……<0.25W / kvar Air clearance
Temperature class TC ………-40°C / B,C,D B x L = 118 x 340mm………90mm
B x L = 144 x 415mm………148mm  




For operation in non-detuning systems

Permitted operating voltages

24h UN
8h/d 1.10 x UN
30min/d 1.15 x UN
5min (200x) 1.20 x UN
1 min (200x) 1.30 x UN
Max. peak rating 3.00 x UN

Test voltages

UBB AC 2.15 x UN

Lower limit temperature -40°C

Dissipation losses

Dielectric <0.20W/kvar
Total capacitor: <0.25W/kvar

Life expectancy (permitted failure rate ≤3%)

At temperature category acc. to chart ……>100.000h

QC CN lN Temp.
L x B x H a m  
(kvar) (uF) (A)   (mm) (mm) (kg) Order No.
UN 3150V 50Hz BIL 10/40kV        
50 3 x 16.0 3 x 9.2 D 118 x 340 x 240 118 15 E90.F24-163300
100 3 x 32.1 3. x 18.3 D 118 x 340 x 315 118 18 E90.F31-323300
150 3 x 48.1 3 x 27.5 D 118 x 340 x 375 118 21 E90.F37-483300
200 3 x 64.2 3 x 36.7 D 118 x 340 x 525 118 28 E90.F52-643300
250 3 x 80.2 3 x 45.8 C 118 x 340 x 525 118 28 E90.F52-803300
300 3 x 96.2 3 x 55.0 C 144 x 415 x 440 150 33 E90.G44-963300
350 3 x 112.3 3 x 64.2 B 144 x 415 x 525 150 39 E90.G52-114300
400 3 x 128.3 3 x 73.3 B 144 x 415 x 525 150 39 E90.G52-134300
UN 6300V 50Hz BIL 20/60kV        
50 3 x 4.01 3 x 4.6 D 118 x 340 x 275 118 16 E90.F27-402300
100 3 x 8.02 3 x 9.2 D 118 x 340 x 375 118 21 E90.F37-802300
150 3 x 12.0 3 x 13.7 D 118 x 340 x 440 118 24 E90.F44-123300
200 3 x 16.0 3 x 18.3 D 118 x 340 x 525 118 28 E90.F52-163300
250 3 x 20.0 3 x 22.9 C 118 x 340 x 625 118 46 E90.F62-203300
300 3 x 24.1 3 x 27.5 C 118 x 415 x 585 150 43 E90.G58-243300
350 3 x 28.1 3 x 32.1 B 144 x 415 x 625 150 46 E90.G62-283300
400 3 x 32.1 3 x 36.7 B 144 x 415 x 625 150 46 E90.G62-323300
UN 10500V 50Hz BIL 28/75kV        
50 3 x 1.44 3 x 2.7 D 118 x 340 x 275 118 16 E90.F27-142300
100 3 x 2.89 3 x 5.5 D 118 x 340 x 440 118 24 E90.F44-292300
150 3 x 4.33 3 x 8.2 D 118 x 340 x 525 118 28 E90.F52-432300
200 3 x 5.77 3 x 11.0 D 118 x 340 x 585 118 31 E90.F58-582300
250 3 x 7.22 3 x 13.7 C 144 x 415 x 525 150 39 E90.G52-722300
300 3 x 8.66 3 x 16.5 C 144 x 415 x 585 150 43 E90.G58-872300
400 3 x 11.5 3 x 22.0 B 144 x 415 x 665 150 48 E90.G66-123300




For detuned systems with adjusted rating at 6…8%

Permitted operating voltages

24h UN
8h/d 1.10 x UN
30min/d 1.15 x UN
5min (200x) 1.20 x UN
1 min (200x) 1.30 x UN
Max. peak rating 3.00 x UN

Test voltages

UBB AC 2.15 x UN

Lower limit temperature -40°C

Dissipation losses

Dielectric <0.20W/kvar
Total capacitor: <0.25W/kvar

Life expectancy (permitted failure rate ≤3%)

At temperature category acc. to chart >100.000h

QLC @ Unetz QC @ UN CN lN Temp.
L x B x H a m  
(kvar) (kvar) (uF) (A)   (mm) (mm) (kg) Order No.
Unetz 3000V UN 3300V 50Hz BIL 10/40kV  
50 56 3 x 16.4 3 x 9.8 D 118 x 340 x 240 118 15 E90.F24-163301
100 113 3 x 32.9 3 x 19.7 D 118 x 340 x 375 118 21 E90.F37-333300
150 169 3 x 49.3 3 x 29.5 D 118 x 340 x 525 118 28 E90.F52-493300
200 225 3 x 65.8 3 x 39.4 D 118 x 340 x 625 118 33 E90.F62-663300
250 281 3 x 82.2 3 x 49.2 C 118 x 340 x 745 118 38 E90.F74-823300
300 338 3 x 98.7 3 x 59.1 B 144 x 415 x 625 150 46 E90.G62-993300
400 450 3 x 132.0 3 x 78.8 B 144 x 415 x 755 150 55 E90.G75-134300
Unetz 6000V UN 6600V 50Hz BIL 20/60kV  
50 56 3 x 4.11 3 x 4.9 D 118 x 340 x 275 118 16 E90.F27-412300
100 113 3 x 8.22 3 x 9.8 D 118 x 340 x 375 118 21 E90.F37-822300
150 169 3 x 12.3 3 x 14.8 D 118 x 340 x 525 118 39 E90.F52-123300
200 225 3 x 16.4 3 x 19.7 D 118 x 340 x 585 118 31 E90.F58-163300
250 281 3 x 20.6 3 x 24.6 C 118 x 340 x 745 118 38 E90.F74-213300
300 338 3 x 24.7 3 x 29.5 B 144 x 415 x 585 150 43 E90.G58-253300
400 450 3 x 32.9 3 x 39.4 B 114 x 415 x 755 150 55 E90.G75-333300
Unetz 10000V UN 10900V 50Hz BIL 28/75kV  
50 55 3 x 1.47 3 x 2.9 D 118 x 340 x 315 118 18 E90.F31-152300
100 110 3 x 2.96 3 x 5.9 D 118 x 340 x 440 118 24 E90.F44-302300
150 166 3 x 4.44 3 x 8.8 D 118 x 340 x 525 118 28 E90.F52-442300
200 221 3 x 5.92 3 x 11.7 D 118 x 340 x 585 118 31 E90.F58-592300
250 276 3 x 7.40 3 x 14.6 C 118 x 415 x 585 150 43 E90.G58-742300
300 331 3 x 8.88 3 x 17.6 B 144 x 415 x 585 150 43 E90.G58-892300
400 442 3 x 11.8 3 x 23.4 B 144 x 415 x 665 150 48 E90.G66-123301




For detuned systems with adjusted rating at 12…14.8%

Permitted operating voltages

24h UN
8h/d 1.10 x UN
30min/d 1.15 x UN
5min (200x) 1.20 x UN
1 min (200x) 1.30 x UN
Max. peak rating 3.00 x UN

Test voltages

UBB AC 2.15 x UN
Lower limit temperature -40°C

Dissipation losses

Dielectric <0.20W/kvar
Total capacitor: <0.25W/kvar

Life expectancy (permitted failure rate ≤3%)

At temperature category acc. to chart >100.000h

QLC @ Unetz QC @ UN CN lN Temp.
L x B x H a m  
(kvar) (kvar) (uF) (A)   (mm) (mm) (kg) Order No.
Unetz 3000V UN 3300V 50Hz BIL 10/40kV  
50 61 3 x 15.1 3 x9.8 D 118 x 340 x 275 118 16 E90.F27-153300
100 123 3 x 30.1 3 x 19.7 D 118 x 340 x 375 118 21 E90.F37-303300
150 184 3 x 45.2 3 x 29.5 D 118 x 340 x 525 118 28 E90.F52-453300
200 245 3 x 60.3 3 x 39.4 D 118 x 340 x 625 118 33 E90.F62-603300
250 307 3 x 75.3 3 x 49.2 B 118 x 340 x 745 118 38 E90.F74-753300
300 368 3 x 90.4 3 x 59.0 B 144 x 415 x 625 150 46 E90-G62-903300
400 491 3 x 120.5 3 x 78.7 B 144 x 415 x 755 150 55 E90-G75-124300
Unetz 6000V UN 7100V 50Hz BIL 20/60kV  
50 60 3 x 3.77 3 x 4.9 D 118 x 340 x 315 118 18 E90.F31-382300
100 119 3 x 7.5 3 x 9.7 D 118 x 340 x 440 118 24 E90.F44-752300
150 179 3 x 11.3 3 x 14.6 D 118 x 340 x 525 118 28 E90.F52-113300
200 239 3 x 15.1 3 x 19.4 D 118 x 340 x 625 118 33 E90.F62-153300
250 298 3 x 18.8 3 x 24.3 C 118 x 340 x 745 118 38 E90.F74-193300
300 358 3 x 22.6 3 x 29.1 B 144 x 415 x 665 150 48 E90.G66-233300
400 477 3 x 30.1 3 x 38.8 B 144 x 415 x 755 150 55 E90.G75-303300
Unetz 10000V UN 11800V 50Hz BIL 28/75kV  
50 59 3 x 1.36 3 x 2.9 D 118 x 340 x 315 118 18 E90.F31-142300
100 119 3 x 2.71 3 x 5.8 D 118 x 340 x 525 118 28 E90.F52-272300
150 178 3 x 4.07 3 x 8.7 D 118 x 340 x 585 118 31 E90.F58-412300
200 237 3 x 5.42 3 x 11.6 D 118 x 340 x 665 118 35 E90.F66-542300
250 297 3 x 6.78 3 x 14.5 C 118 x 415 x 585 150 43 E90.G58-682300
300 356 3 x 8.13 3 x 17.4 B 144 x 415 x 625 150 46 E90.G62-812300
400 475 3 x 10.8 3 x 23.2 B 144 x 415 x 755 150 55 E90.G75-113300




For operation in non-detuning systems

Permitted operating voltages

24h UN
8h/d 1.10 x UN
30min/d 1.15 x UN
5min (200x) 1.20 x UN
1 min (200x) 1.30 x UN
Max. peak rating 3.00 x UN

Test voltages

UBB AC 2.15 x UN

Lower limit temperature -40°C

Dissipation losses

Dielectric <0.20W/kvar
Total capacitor: <0.25W/kvar

Life expectancy (permitted failure rate ≤3%)

At temperature category acc. to chart >100.000h

QC CN lN Temp. category L x B x H a m  
(kvar) (uF) (A)   (mm) (mm) (kg) Order No.
UN 2400V 60Hz BIL 13/45kV        
50 3 x 23.0 3 x 12.0 D 118 x 340 x 240 118 15 E90.F24-233400
100 3 x 46.1 3. x 24.1 D 118 x 340 x 375 118 21 E90.F37-463400
150 3 x 69.1 3 x 36.1 D 118 x 340 x 440 118 24 E90.F44-693400
200 3 x 92.1 3 x 48.1 D 118 x 340 x 525 118 28 E90.F52-923400
250 3 x 115.1 3 x 60.1 C 118 x 340 x 585 118 31 E90.F58-124400
300 3 x 138.2 3 x 72.2 C 144 x 415 x 525 150 39 E90.G52-144400
400 3 x 184.2 3 x 96.2 B 144 x 415 x 585 150 43 E90.G58-184400
UN 4160V 60Hz BIL 24/75kV        
50 3 x 7.66 3 x 6.9 D 118 x 340 x 240 118 15 E90.F24-772400
100 3 x15.3 3 x 13.9 D 118 x 340 x 315 118 18 E90.F31-153400
150 3 x 23.0 3 x 20.8 D 118 x 340 x 440 118 24 E90.F44-233400
200 3 x 30.7 3 x 27.8 D 118 x 340 x 525 118 28 E90.F52-313400
250 3 x 38.3 3 x 34.7 C 118 x 340 x 585 118 31 E90.F58-383400
300 3 x 46.0 3 x 41.6 C 144 x 415 x 440 150 33 E90.G44-463400
400 3 x 61.3 3 x 55.5 B 144 x 415 x 625 150 43 E90.G58-613400