Harmonics In Electrical Networks
The harmonic is defined as one of the components obtained from the breakdown of a periodic wave in the Fourier series. The order of a harmonic is further defined as the ratio between the frequency of the harmonic and the fundamental frequency of the periodic wave considered. 

In the case of the perfectly sinusoidal waveform (as should characterize the voltage supplied by the utility) only the fundamental harmonic of the first order will be present, which in India has a frequency of 50 Hz.

If a sinusoidal voltage is applied to a load, the circulating current will also have a sinusoidal waveform only in the presence of loads with “linear characteristics”.

In the presence of a “non-linear” load the current waveform will deviate from the ideal pattern and breaking down the wave according to the Fourier theorem will show evidence of harmonics whose number and amplitude will increase with the degree of distortion in the current waveform.

The increasingly frequent use of non-linear loads in industrial facilities (inverters, fluorescent lamps, welders, DC drives etc.) Creates elevated distortions in the waveform of circulating current.

This is true in the case of ac/dc converters, for which the input current theoretically displays only harmonics of the order.

h=mp±1

The parameter used to determine the level of harmonic distortion presents in an electrical network is THD% of voltage & current.


Negative Effects of Harmonics

  • The capacitors are subjected to a voltageoverload and their lifetime is drastically reduced.

  • Connection of the capacitor causes a large increase in the distortion factors THD(V) & THD (I).

  • Motors; Reduced motor life, inability to fully load motor.

  • The user transformers, wires and loads are affected by this increase in current, which leads to increased I R losses and eddy current losses in transformer. This reduces the capacity of transformer resulting into economic loss as well.Apart from this transformer may also be subjected to excessive overheating and saturation.

  • Interference in computers, microprocessor & solid state controlled equipment because of distorted 240 V supply. Increased neutral to ground voltage may cause hardware problems which may initially look like software problem.

  • High voltage distortion shall also be encountered when shifting from mains to emergency generator as they offer high impedance than supply transformer.

  • Large current in neutral wires of power distribution system. This is a real fire hazard as usually phase wires are protected by circuit breakers or fuses.

  • Poor power factor: As mentioned earlier the harmonic current caused by non-linear loads do not carry any real power (KW) even though they do increase the volt amperage (KVA). This lowers the power factor at (Pf=KW/KVA) the main distribution transformer. Utilities put penalties on consumers with low P. F., less than 0.9.

  • Over heating in fuses resulting in false blowing. False / spurious operations of breakers, which may lead to variation in other characteristics.

What do P. F. Correction Capacitors have to do with Harmonics ?

In an industrial plant containing power factor correction capacitors, harmonics distortions can be magnified due to the interaction between the capacitors and the service transformer. This is referred to as harmonic resonance or parallel resonance. It is important to note that capacitors themselves are not main cause of harmonics, but only aggravate potential harmonic problems. Often, harmonic-related problems do not show up until capacitors are applied for power factor correction.

Components of Detuned Systems Controller - Single Phase or 3 Phase

  • Measurement of A, V, PF, CosΦ, W, Var, VA (∑W, ∑VA, ∑VAr etc.)

  • Sense1%of load current

  • Auto/Manual mode selection with indicator light

  • Automatic calculation of C/k value

  • Program entry for targeted CosΦ value

  • Number of capacitor steps are user definable

  • The consequent switching time between capacitor steps is adjustable from 2 to 50 sec.

  • C+/NORMAL/C- condition lights indicate actual system state.

  • Over Voltage Insufficient Compensation, Over Compensation state alarm indicator lights with output contact

  • Adjustable programmable Over Voltage protection for capacitor banks.

  • Micro Controller based digital design complying with international standards.

  • Flush mounting with rear panel connectors.

  • Designed to use with Current T/F (.../5A)   

Data Logger Module with Energy Analyzer (Optional)

Energy Analyzer with Data Logger is having facility to record and display all the 3 Phase parameters of
mains where P.F.C. system is connected.

Capacitors Banks

Neptune-Ducati ranges of Capacitor Banks are using Capacitor Modules from M/s Ducati energia s.p.a,Italy. Ducati energia is a leading company in production of power factor correction capacitors. Following this tradition, continuous investments in research and development of new products have represented the policy of the company.

The result of this philosophy is the new range of Long Life Capacitors MONO16 and MODULO50. Thanks to the technological innovation of self-healing metallized polypropylene; the rated power of 50 KVAR is achieved in just one 3- phase element with very compact dimensions & a much higher life expectancy in comparison with other models. These new Long-Life Capacitors Mono16 & Modulo50 reach an expected life of more than 160,000 hours and a size reduction up

to 40% against the technologies so far applied with low loss of 0.2W/KVAR with 4 In capabilities and oil impregnation, the performance of these capacitors are much better in comparison to other technologies
available in market like gas filled & dry type.

Harmonic Reactors

Neptune Filter Circuits are designed as three-phase reactors with an iron core and air gap. Harmonic Filter Reactors are made out of high quality material and very stringent quality control. It has been designed with properties like low temperature rise and lower flux density so that it can operate in worst conditions of ambient and harmonic overloads.

They offer very good degree of linearity and low losses.Cheaper and non- linear reactors may trigger undesirable chain phenomena during periods of operation with high harmonic values, such as reduction in the inductance with consequent increase in the resonance frequency of the LC group, which would drain off more harmonic current, further reducing its inductance and overload the reactor more and more. Reactors are available with filtering factor of 5.6%, 7% and 14% as per standard ratings. Any other filtering factor and rating can be developed on request.

Other parts of Detuned systems.

  • Other parts of Detuned systems.
  • HRC Fuses
  • ACB and MCCB as Incomer

Activcomp

Neptune can also offer fast Thyristor switched transient free system for power factor correction & harmonic filtration.


Electrical & General Characteristics:

  • Power range: 125 - 1000 KVAR (440V)
  • Mains working voltage- 415-440V (other
    voltages on request)
  • Rated frequency :50 Hz
  • Altitude: 2000ma.s.l.
  • Relative humidity: 70% max. at 20 C
  • Duty :continuous

  • Ambient temperature class:-5+ 45 C
  • Power supply line: Three-phase + ground +
    neutral (for control only) in 3 phase controller
  • 3 phase + ground in single phase controller.
  • Relay current input signal: from 3 no’s or 1no.CT on line.../5A as per controller type.
  • Relay voltage input signal: picked up internally.