Reactor connected (detuned) Capacitors can be installed which are
designed to prevent system resonance. They can also be designed
to reduce the level of harmonics as indicated below.
This reactor / capacitor combination is designed to have a resonant
frequency of 189Hz. In this case, system resonance is avoided and
approximately 17 to 20% of the 5th harmonic current can be absorbed.
This is suitable for variable loads.
Here the reactor / capacitor combination is designed to resonate
at a frequency of 210Hz, again system resonance’s are avoided
and approximately 40 to 50% of the 5th harmonic current can be absorbed.
This is suitable for variable loads where harmonic reduction is
also required.
In this system the capacitor / reactor legs are tuned to a given
harmonic frequency producing almost zero impedance to that harmonic
current. Therefore most of the current is absorbed by the filter.
This type of filter is typically constructed with multiple legs,
each being tuned to a specific harmonic frequency and can realistically
reduce the harmonic current flowing in the supply network by up
to 90%. Ideally, this is suited for constant loads.
Harmonics are generated by equipment termed “Non-Linear”,
that is to say that they present a non-constant voltage to current
ratio and will absorb a non-sinusoidal current when supplied by
a sinusoidal voltage.
Static Power Converters (SCR’s) such as variable speed drives,
frequency converters, soft starts, battery chargers etc
Arc furnaces and electric welding equipment
Certain U.P.S. systems
Single phase electronic equipment employing AC to DC power supplies
Electronic lighting control
Transformers and reactors having a non-linear magnetising curve
Increased losses both on the network and within supply transformers
Nuisance tripping of circuit breakers
Premature ageing of electrical insulation
Malfunction or failure of some electronic circuits
Certain types of metering can be subject to erroneous operation
De-rating of fuses due to the heat generated by harmonics during
normal operation
Possible cause of system resonance when Power Factor Correction
equipment is present on the system. This occurrence can impose high
voltages and currents on the system which is most undesirable
Premature failure of unprotected Power Factor Correction / Capacitor
installations
PFC Engineering Limited have over 25 years experience
in the design and manufacture of Harmonic Filter systems and are
able to offer:
Fully qualified team of engineers to provide assistance and advice
Complete harmonic analysis capability
Design, manufacture and installation specifically to meet customers
requirements
Systems manufactured using high quality components
