Power Factor Correction: why?

The operators in the industrial electrical installation field are more and more sensitive to topics like energy efficiency and waste reduction.

In that respect, power factor correction can play an active role. A properly corrected plant means reduction of Joule losses and voltage drop, which enables optimum sizing of electrical equipment such as power transformers, cables, busbars and switching and protection devices.

If the load power factor is well corrected, the electric distribution is more efficient and stable. This is the reason why in industrialised countries the energy distributing bodies reward virtuous industrial users by applying penalties when the consumed reactive energy exceeds the set limit.

A plant ‘quality index’ is given by the power factor (cos φ), i.e. the ratio between active and apparent power: the higher the power factor, the better the plant quality.

Generally speaking, the distributing bodies set the value between 0.9 and 0.95).

In the majority of low power factor plants, the cost relevant to the installation of a power factor correction unit is amortised within a few years.

Power Factor Correction: how?

By installing a capacitor battery, it is possible to reduce the reactive power absorbed by the inductive loads connected thus increasing the power factor.

There are several ways to perform the power factor correction and the choice depends on daily load duty-cycle, load distribution and type of service.

The main choice is between distributed or centralized power factor correction.

If the correction system is distributed, the units are located in the vicinity of each load for which the power factor needs to be corrected. In case of centralized correction, a single automatic unit is installed upstream the load that need to be corrected.

Technically speaking, the distributed system is to prefer because the power factor correction becomes systematic and strongly linked to the affected load. In industrial plants savings are achieved in terms of tariffs but also in terms of better design of all the electric lines in the facility connecting the MV/LV cabin to the loads. Another noticeable advantage prided by this type of correction, is that the installation is simple and not expensive. Power factor correction systems and loads are energised and de-energised at the same time, thus exploiting the same protections against overload and short-circuit.

Another key element to consider is the daily load duty-cycle: very often, not all the loads work at the same time and some are operative only for a few hours during the day. In this case, it is clear that the distributed configuration would be too expensive due to the high number of correction systems that would need to be installed and the idle time of several units.

In conclusion, the distributed configuration is most efficient when the majority of the required reactive power is concentrated on few high power loads working for many hours during the day. The centralized configuration, on the other hand, is suitable for situations where there are many diverse loads working sporadically. In this case, the bank power is much lower that the overall power that would be necessary with a distributed configuration.

Should the reactive power absorption be very changeable during the plant operating time, it is recommendable to choose an automatic correction system splitting the bank into several steps.

Power Factor Correction: harmonics in electric lines

Current distortion (i.e., harmonics) in industrial or tertiary electric plants is generated by non-linear loads such as inverters, welders, rectifiers, computers, drives and so on. The distortion is represented by the number THDI%: if the current is sinusoidal, the THDI% is nil. The more the current is distorted, the higher is its THDI% value.

Their connection to the mains causes several problems in an electric system:

– Rotating machinery: generation of eddy torques (and consequent vibrations) that undermine the mechanical structure. The loss increase causes undesired overheating and isolation damage.

– Transformers: increase of core and winding losses, with potential winding damage. The potential presence of DC voltage or current components may saturate the magnetic core, thus increasing the magnetizing current.

– Capacitors: overheating and voltage increase, both causing a reduction of the expected life.

If periodic, the waveform of the current generated by a non-linear load can be represented as the sum of several sinusoidal waves at different frequency (the wave at 50Hz is called fundamental, whilst the ones at frequency multiple of the fundamental are called harmonics).

It is generally not recommended to correct the power factor in a system with high harmonic content without any device dealing with the harmonics.Even though capacitors able to withstand high overloading could be provided, power factor correction performed only via capacitors actually increases the harmonic disturbance and the related negative effects.

The best solution for this type of issue is the detuned filter obtained by connecting reactances in series to the capacitors. The reactances shift the system resonance frequency below the lowest existing harmonic thus protecting the capacitors and avoiding dangerous resonance phenomena.

Used capacitors

Inside ORTEA automatic power factor correction systems there are only three-phase polypropylene metalized high gradient capacitors resin filled (PCB free).

The fundamental difference with respect to the standard polypropylene capacitors is how the dielectric film is metallized: if in the standard capacitors the metal layer thickness deposited on the polypropylene film surface is constant, for the «high gradient» ones the metal layer has a suitably modulated thickness.

The metallization thickness modulation greatly improves the capacitors (and therefore of the power factor correction systems, of which they are the a critical component) performance in terms of:

– Increase in power density (kvar/dm3) with a consequent power size reduction of the power factor correction systems;

– Robustness against voltage surges, for geater reliability even in systems with the presence of voltage fluctuations due to the network or maneuvers on the system;

– Improved behaviour in relation to internal short circuit withstand.

Reactive power regulators

The reactive power regulator, together with capacitors and reactors (in detuned filter cabinets) is, the key component of the automatic power factor correction system.

It is actually the ‘intelligent’ element responsible for the verification of the power factor of the load, depending on which it controls the ON/OFF switching of the capacitors batteries. By doing so, the regulator maintains the system power factor above the minimum threshold set by the Energy Authority.

The reactive power regulators RPC used in automatic ORTEA power factor correction systems are designed to provide for the desired power factor while minimizing the wear & tear of the banks of capacitors.

Accurate and reliable in their measuring and control functions, the regulators are simple and intuitive to install and use.

The flexibility of ORTEA regulators enables the modification of all the parameters, so that they can be customize to suit the actual characteristics of the system that needs correction (threshold power factor, step switching sensitivity, steps reconnecting time, presence of photovoltaic systems, etc.).

ORTEA regulators also offer important features for maintaining and managing the power factor correction bank in order to identify and solve problems which could otherwise lead to damage and life expectancy reduction.

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PFC POWER FACTOR CORRECTION SYSTEMS

PFC403

Ortea
Manufactured by: Ortea
Model: PFC403
Product ID: 5693
Un = 450V
THDIR% ≤ 20%

PFC103
UeUnUmaxHzTHDIR%THDIC%
415V450V495V50≤ 20%≤ 70%
Ue: Rated voltage. Un: Capacitors rated voltage. Umax: Capacitors admissible maximum voltage. THDIR%: Admissible current total harmonic distortion of the plant. THDIC%: Admissible current total harmonic distortion of the capacitors.
Technical characteristics
Rated operational voltageUe = 415V
Rated frequency50Hz
Max current overload In (PFC unit)1.3xIn
Max current overload In (capacitors)1.3xIn (continuous)
Max voltage overload Vn (PFC unit)1.1xUe
Max voltage overload Vn (capacitors)3xUn (for 1 minute)
Temperature range (PFC unit)-5/+40°C
Temperature range (capacitors)-25/+55°C
Discharge deviceOn each bank
InstallationIndoor
ServiceContinuous
Capacitors connectionDelta
Operation devicesContactors (AC6b)
Inner surface finishZinc passivation
Applicable standards (cabinet)IEC 61439-1/2 IEC61921
Applicable standards (capacitors)IEC 60831-1/2
Main characteristics
Power factor correction systems indicated for plants where the current harmonic distortion (without capacitors installed) is lower/equal than 20%. Use of high energy density metallised polypropylene capacitors ensures enhanced performance, high resistance to strong voltage overload, low losses and contained dimensions.
Generalities
  • Zinc-passivated metallic enclosure painted with epossidic dust paint, colour RAL 7035.
  • Auxiliary transformer to separate power and auxiliary circuit parts (230V).
  • Load-break switch with door interlock.
  • Contactors for capacitive loads with damping resistors to limit capacitors’ inrush current.
  • Self-extinguish cable according to IEC 50267-2-1 standards.
  • Microprocessor power factor correction relay.
  • Un = 450V three phase self-healing high energy density metallized polypropylene capacitors.
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PFC POWER FACTOR CORRECTION SYSTEMS

PFC503

Ortea
Manufactured by: Ortea
Model: PFC503
Product ID: 1155
Un = 525V
THDIR% ≤ 27%

PFC503
UeUnUmaxHzTHDIR%THDIC%
415V525V577V50≤ 27%≤ 85%
Ue: Rated voltage. Un: Capacitors rated voltage. Umax: Capacitors admissible maximum voltage. THDIR%: Admissible current total harmonic distortion of the plant. THDIC%: Admissible current total harmonic distortion of the capacitors.
Technical characteristics
Rated operational voltageUe = 415V
Rated frequency50Hz
Max current overload In (PFC unit)1.3xIn
Max current overload In (capacitors)1.3xIn (continuous)
Max voltage overload Vn (PFC unit)1.1xUe
Max voltage overload Vn (capacitors)3xUn (for 1 minute)
Temperature range (PFC unit)-5/+40°C
Temperature range (capacitors)-25/+55°C
Discharge deviceOn each bank
InstallationIndoor
ServiceContinuous
Capacitors connectionDelta
Operation devicesContactors (AC6b)
Inner surface finishZinc passivation
Applicable standards (cabinet)IEC 61439-1/2 IEC61921
Applicable standards (capacitors)IEC 60831-1/2
Main characteristics
Power factor correction systems indicated for plants where the current harmonic distortion (without capacitors installed) is lower/equal than 27%. Use of high energy density metallised polypropylene capacitors ensures enhanced performance, high resistance to strong voltage overload, low losses and contained dimensions.
Generalities
  • Zinc-passivated metallic enclosure painted with epossidic dust paint, colour RAL 7035.
  • Auxiliary transformer to separate power and auxiliary circuit parts (230V).
  • Load-break switch with door interlock.
  • Contactors for capacitive loads with damping resistors to limit capacitors’ inrush current.
  • Self-extinguish cable according to IEC 50267-2-1 standards.
  • Microprocessor power factor correction relay.
  • Un = 525V three phase self-healing high energy density metallized polypropylene capacitors.
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PFC POWER FACTOR CORRECTION SYSTEMS

PHF203

Ortea
Manufactured by: Ortea
Model: PHF203
Product ID: 1162
Un = 525V
THDIR% ≤ 27%

PHF203
UeHzTHDIR%THDVR%I(250Hz)%Detuning choke (180Hz - N=3,6 - P=7,7%)
415V50>27%≤ 6%≤ 25%100% non linear load connected
Ue: Rated voltage. THDIR%: Admissible current total harmonic distortion of the plant. THDIVr%: Admissible voltage total harmonic distortion of the plant. I(250Hz)%: Percentage 5th harmonic current.
Technical characteristics
Rated operational voltageUe = 415V
Rated frequency50Hz
Max current overload In (PFC unit)1.3xIn
Max current overload In (capacitors)1.3xIn (continuous)
Max voltage overload Vn (PFC unit)1.1xUe
Max voltage overload Vn (capacitors)3xUn (for 1 minute)
Temperature range (PFC unit)-5/+40°C
Temperature range (capacitors)-25/+55°C
Discharge deviceOn each bank
InstallationIndoor
ServiceContinuous
Capacitors connectionDelta
Operation devicesContactors
Inner surface finishZinc passivation
Applicable standards (cabinet)IEC 61439-1/2 IEC61921 IEC61642
Applicable standards (capacitors)IEC 60831-1/2
Main characteristics
Power factor correction systems indicated for plants where the current harmonic distortion (without capacitors installed) is higher than 27%. Use of high energy density metallised polypropylene capacitors ensures enhanced performance, high resistance to strong voltage overload, low losses and contained dimensions.
Generalities
  • Zinc-passivated metallic enclosure painted with epossidic dust paint, colour RAL 7035.
  • Auxiliary transformer to separate power and auxiliary circuit parts (230V).
  • Load-break switch with door interlock.
  • Contactors.
  • Self-extinguish cable according to IEC 50267-2-1 standards.
  • Microprocessor power factor correction relay fitted with harmonic protection module.
  • Un = 525V three phase self-healing high energy density metallized polypropylene capacitors.
  • Three-phase detuning chokes with (180Hz tuning frequency).
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PFC POWER FACTOR CORRECTION SYSTEMS

PHF303

Ortea
Manufactured by: Ortea
Model: PHF303
Product ID: 5702
Un = 525V
THDIR% >27%

PHF203
UeHzTHDIR%THDVR%I(250Hz)%Detuning choke (135Hz - N=2,7 - P=13,7%)
415V50>27%≤ 6%>25%100% non linear load connected
Ue: Rated voltage. THDIR%: Admissible current total harmonic distortion of the plant. THDIVr%: Admissible voltage total harmonic distortion of the plant. I(250Hz)%: Percentage 5th harmonic current.
Technical characteristics
Rated operational voltageUe = 415V
Rated frequency50Hz
Max current overload In (PFC unit)1.3xIn
Max current overload In (capacitors)1.3xIn (continuous)
Max voltage overload Vn (PFC unit)1.1xUe
Max voltage overload Vn (capacitors)3xUn (for 1 minute)
Temperature range (PFC unit)-5/+40°C
Temperature range (capacitors)-25/+55°C
Discharge deviceOn each bank
InstallationIndoor
ServiceContinuous
Capacitors connectionDelta
Operation devicesContactors
Inner surface finishZinc passivation
Applicable standards (cabinet)IEC 61439-1/2 IEC61921 IEC61642
Applicable standards (capacitors)IEC 60831-1/2
Main characteristics
Power factor correction systems indicated for plants where the current harmonic distortion (without capacitors installed) is higher than 27%. Use of high energy density metallised polypropylene capacitors ensures enhanced performance, high resistance to strong voltage overload, low losses and contained dimensions.
Generalities
  • Zinc-passivated metallic enclosure painted with epossidic dust paint, colour RAL 7035.
  • Auxiliary transformer to separate power and auxiliary circuit parts (230V).
  • Load-break switch with door interlock.
  • Contactors.
  • Self-extinguish cable according to IEC 50267-2-1 standards.
  • Microprocessor power factor correction relay fitted with harmonic protection module.
  • Un = 525V three phase self-healing high energy density metallized polypropylene capacitors.
  • Three-phase detuning chokes with (135Hz tuning frequency).
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PFC POWER FACTOR CORRECTION SYSTEMS

PHS203

Ortea
Manufactured by: Ortea
Model: PHS203
Product ID: 5703
Un = 525V
THDIR% >27%

PHF203
UeHzTHDIR%THDVR%I(250Hz)%Detuning choke (180Hz - N=3,6 - P=7,7%)
415V50>27%≤ 6%≤ 25%100% non linear load connected
Ue: Rated voltage. THDIR%: Admissible current total harmonic distortion of the plant. THDIVr%: Admissible voltage total harmonic distortion of the plant. I(250Hz)%: Percentage 5th harmonic current.
Technical characteristics
Rated operational voltageUe = 415V
Rated frequency50Hz
Max current overload In (PFC unit)1.3xIn
Max current overload In (capacitors)1.3xIn (continuous)
Max voltage overload Vn (PFC unit)1.1xUe
Max voltage overload Vn (capacitors)3xUn (for 1 minute)
Temperature range (PFC unit)-5/+40°C
Temperature range (capacitors)-25/+55°C
Discharge deviceOn each bank
InstallationIndoor
ServiceContinuous
Capacitors connectionDelta
Operation devicesElectronic Fast Switches
Inner surface finishZinc passivation
Applicable standards (cabinet)IEC 61439-1/2 IEC61921 IEC61642
Applicable standards (capacitors)IEC 60831-1/2
Main characteristics
Power factor correction systems indicated for plants with very fast working cycles (from 150 msecs to 1 sec) and high current harmonic distortion (higher than 27%). Use of high energy density metallised polypropylene capacitors ensures enhanced performance, high resistance to strong voltage.
Generalities
  • Zinc-passivated metallic enclosure painted with epossidic dust paint, colour RAL 7035.
  • Auxiliary transformer to separate power and auxiliary circuit parts (230V).
  • Load-break switch with door interlock.
  • Electronic fast switches.
  • Self-extinguish cable according to IEC 50267-2-1 standards.
  • Microprocessor power factor correction relay fitted with harmonic protection module.
  • Un = 525V three phase self-healing high energy density metallized polypropylene capacitors.
  • Three-phase detuning chokes with (180Hz tuning frequency).
  • Total available reactive power switching time: approximately 60millisecs.
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PFC POWER FACTOR CORRECTION SYSTEMS

Racks

Ortea
Manufactured by: Ortea
Model: Racks
Product ID: 5708


cassetti

Designed to suit the most common switchboard sizes, ORTEA's rack system is the ideal solution for OEM and switchboard manufacturers. The rack is:

  • Compact
  • Available with or without blocking reactor
  • Available in a single rack from 9.4kvar to 150kvar
  • Fitted with busbars sized to withstand up to 400kvar
  • Easy to assemble (busbars and NH fuses incorporated in the rack support)

ORTEA racks are fitted with three-phase self-regenerating high energy-density metallised polypropylene capacitors ensuring enhanced performance, low losses and contained dimensions.

The lateral adjustable slides allow for quick and easy assembling operations inside any cabinets. Thanks to its extensible brackets, the 480mm rack can be mounted in a 800mm cabinet thus enabling a flexible combination of sizes and total reactive power.

The busbar system can withstand a maximum reactive power equal to 400kvar (at 415V, 50Hz). Rack can be added to the system at any time.

Each auxiliary and control component is supplied already wired to the terminal block assembled on the rack.

Standard features

Each rack is supplied complete with:

  • Contactors for capacitors
  • Self-extinguishing cables (EN50267-2-1)
  • NH00 single-pole fuse holder.
  • NH00 gG power fuses
  • Three-phase self-regenerating high energy-density metallised polypropylene capacitors
  • Three-phase connecting system via tinned copper bars
  • Discharging resistors
  • Only for the H203 type, blocking reactor with 180Hz tuning frequency All the components conform with the safety legislative provisions.

Standard accessories (in every rack)

  • Telescopic side brackets, suitable for 600-400mm deep cabinets
  • Tinned copper connection bars, complete with bolts
  • IP20 Plexiglass protection
  • Adapting brackets for installation inside cabinet with different width (800-1000mm)

The P403 rack technical characteristics are the same as the ones valid for the PFC403 automatic power factor correction systems. The same applies for P503 (PFC503), H203 (PHF203), H303 (PHF303) and HS203 (PHS203).

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