|  Many
types of power conversion equipment connected to the
public electricity supply and to other power networks
are generating dangerous harmonic current distortion
due to the non linear characteristic of the loads. This
harmonic distortion is reflected back into the power
source and is often contaminated further with resonant
frequencies as a result of interaction between correction
devices and the non linear load, consequently this affects
the stability of the Public Utility distribution networks
feeding other loads connected to the network.
Non linear loads are creating serious
problems in power distribution systems largely due to
the proliferation of high crest factor power stages
used the in design of such familiar equipment, the notable
culprits are, variable speed motor drives, rectifier
battery chargers, personal computers, LAN computer systems,
TV monitors, office equipment, PABX phone systems, elevators,
air conditioning systems, UPS systems, discharge lighting,
motorised domestic appliances inadequately designed
power factor correction equipment, lighting dimmer equipment
etc.
The non linear loads generate a distorted
harmonic current wave form which is no longer sinusoidal
and flows from the load towards the power source and
follows the path of least impedance. The harmonic current
distortion adversely affects virtually every component
in the power distribution system creating dielectric
stress, mechanical stress, overheating of cables, transformers
and motors, sporadic tripping of protection devices,
overheating of the neutral current conductor in a three
phase distribution system etc. The harmonic currents
flowing through the impedance of a power distribution
system will result in voltage instability with the maximum
danger occurring when the system inductive reactance
equals the capacitance reactance.
We offer a custom engineering evaluation,
design and installation service to provide the best
appropriate filters to absorb, compensate and correct
harmonic distortion at the load, where the actual problem
is generated or at the power distribution board if correction
at the load is not possible. The harmonic correction
can be often combined with a custom engineered multi
step power factor correction system.
The types of filters we can offer are,
- Dynamic active injection
- Phase shifting
- Passive broad band
- Matrix, multi stage low pass.
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