2
Introduction
OperatiOnal manual
MN156001EN October 2015 www.eaton.com
Introduction
The product can be provided in either of two types, an
Harmonic Correction Unit (HCU2) or an Electronic VAR
Injector (EVI2). Both types are to be installed as described
in this manual. These products are both referred to as an
active filter in this manual. For the most part, operation is
the same for both types. Where there are differences, they
are indicated by [HCU2] or [EVI2] in the topic heading. For
example, the information in Harmonic Enable [HCU2 type]
on
page 14
pertains to HCU2 type active filters.
Harmonic correction unit
Active Harmonic Filters (HCU2) are static power electronic
products that employ digital logic and IGBT semiconductors
to synthesize a current waveform that is injected into the
electrical network to cancel harmonic currents caused
by nonlinear loads. HCU2 employ current transformers
to measure the load current to determine the content of
harmonic current present. By injecting the synthesized
current, network harmonic currents are greatly mitigated,
thus reducing the heating effects of harmonic current and
reducing voltage distortion to permit other equipment to
operate properly and enjoy a long product life span.
HCU2 also have the ability to correct for poor displacement
power factor (DPF) and for mains current balancing. DPF
correction can be provided for either leading (capacitive) or
lagging (inductive) loads that cause poor DPF. Mains current
balancing is achieved by measuring the negative sequence
current present and injecting the inverse negative sequence
current to balance the current for the upstream network.
Electronic VAR injector
Electronic VAR injector (EVI2) are static power electronic
products that employ digital logic and IGBT semiconductors
to synthesize a current waveform that is injected into the
electrical network to cancel load induced poor displacement
power factor (DPF), phase current unbalance, and
flicker. DPF correction can be provided for either leading
(capacitive) or lagging (inductive) loads that cause poor
DPF. Mains current balancing is achieved by measuring the
negative sequence current present and injecting the inverse
negative sequence currents to balance the current for the
network. Flicker control is provided by rapid detection and
injection of reactive current (VARs) to prevent the reactive
current from over loading the network that causes rapid
voltage deviations identified as flicker.
EVI2 also have the ability to monitor the network voltage
on which they are connected and determine the proper
amount of VARs to either raise the network voltage or
lower it. EVI2 will inject leading VARs to raise the voltage
and lagging VARs to lower the voltage. Entry of appropriate
parameters will keep the network within its stated voltage
tolerance level.
