up projects in Harmonics involving harmonic audit,
recommendation and installation of filters. The
products and services in this area covers the
of Filter System
commissioning of Filter System
Modern industries requires automation of their
operation enabling them to produce quality products
and also for mass production. The conventional
systems are being replaced by modern Power Electronic
systems, bringing a variety of advantages to the
users. Classic examples are D.C. & AC Drives,
UPS, soft starters, etc. Since the thyristor converter
technology is rapidly gaining ground in the modern
industrial plants, the power supply systems are
contaminated as the ideal sinusoidal current and
voltage waveforms are getting distorted. This
in turn is affecting the performance of the equipment
in the electrical network, especially the Power
Factor correction capacitors.
I. Sources of Harmonics:
Non linear loads as mentioned below are the
main sources of Harmonics in the electrical network:
1. AC Variable Frequency Drives
2. D.C. Thyristor Converter Drives
3. Induction Furnaces & Thyristor Controlled
5. UPS & SMPS (Used in Computers & Automation
6. Electronic Ballast
II. Effects of Harmoncs:
heating due to iron and copper losses in machines
at higher frequencies.
pairs such as 5th and 7th have potential to create
mechanical oscillation in Motor-Load or Turbine-Generator
combination. This in turn may produce oscillating
torque. Also, these harmonic currents generate
heat in the electrical network and in motor windings
in both stator and rotor.
create increased level of noise and harmonic current
causes additional copper and stray flux losses.
Harmonic voltages cause increase in iron losses.
have voltage stress and corona leading insulation
failure and also higher, skin effect.
Power Factor improvement capacitors and Poor Power
equipment are susceptible to mis-operation caused
by harmonic distortion (shift in voltage crossing).
of Meters and instruments can be affected with
high harmonic distortions and may show erratic
in switch gear increase heating and thus excess
losses. It can also affect operation of relays.
III. Solution to Harmonics:
Distortion in the voltage and current wave form
is not desirable in the electrical network because
of their adverse impact on the connected equipment.
It is therefore, prudent to install tuned harmonic
filters close to the loads generating harmonic
currents so that the harmonic currents are filtered
at the source and relieving the network from the
evil effects of harmonics. A Harmonic Filter system
basically consists of Capacitor bank connected
in delta and a series reactor. These will be housed
in a suitable panel along with necessary switch
gear and meters. The filter injects required kVAr
to the network and improve the Power Factor till
the tuned frequency and beyond the tuned harmonic
frequency, it will be inductive and thus prevent
amplification of harmonic currents.
IV. The Benefits by installing Harmonic Filter
in Energy Losses & reduced energy bill
in unexpected demand of energy due to harmonic
failure and maintenance
life of electrical equipment, measuring instruments
interruption and downtime
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