Triplett Mitigator Loop Coil – 3232 - Manual (Page 23)

single bushing capacitors will not have a “live” housing (except under power fault or surge conditions),
it is still recommended that the capacitor bank be of the “double bushing” type. If the existing capacitor
bank is of the “single bushing” type, it is recommended that it be changed to a double bushing type.
“Semi-Floating” has no effect upon the 60Hz [50Hz] performance of the capacitor, and hence, does not
affect the power factor correction abilities of the capacitor. It only prevents harmonic currents from
flowing to earth ground at the capacitor.
For the purpose of determining whether floating or semi-floating a capacitor bank will produce the
desired noise reduction, the capacitor can be temporarily floated, even if it is a single bushing type.
To monitor the effect that floating or semi-floating the capacitor produces, a loop coil in the immediate
vicinity of the capacitor bank should register a reduction in level when the bank is floated. Additionally,
a craftsperson monitoring the Power Influence on the noisy line(s) should also see a reduction in level.
Many power companies that routinely float capacitor banks “tag” the floated banks at the bottom of the
poles and at the capacitors themselves.
In some situations, the capacitors are located on the ground, but the technique used to reduce har-
monic current flow to the earth ground is the same.
The induction caused by both resonant and sink effects in the power line can often be suppressed by
floating the appropriate capacitor banks. Note that floating a capacitor bank is usually much easier than
relocating a capacitor bank. Hence, if allowed by the local power company, floating should be exam-
ined before going through a relocation.
14.5: HSR’S
Harmonic Suppression Reactors (HSRs) offer another method of noise reduction. As their name im-
plies, they suppress harmonic currents. “Reactor” is another name for a coil or choke.
HSRs are placed on the power lines. They are only recommended for use on 3 phase lines, although
they have sometimes been used on 2 phase lines.
An HSR reduces harmonic current flow in the phase wires and the neutral. It can sometimes provide a
greater degree of noise reduction than obtained by floating a capacitor bank.
As previously discussed, a capacitor can create a resonant condition on the power line or act as a
“sink”. Often, a capacitor will both resonant to some degree AND act as a sink.
An HSR is an effective means of reducing harmonic current flow through a capacitor while having only
a minor effect upon the 60Hz [50Hz] current. This allows it to work without significantly affecting the
power factor of the power line. The HSR is essentially wired in series with the capacitor bank and
prevents harmonic current flow through it. Since it is wired in series, it must handle all of the residual
current (60Hz [50Hz] current) as well as the harmonic current.
In order to be effective, the HSR must be “tuned” to work correctly in a specific application. Conse-
quently, when an HSR is to be used to solve a noise problem, a “test reactor” is temporarily installed in
the circuit and is tuned to suppress the problem harmonic currents (while causing the minimum of side
effects). When the proper inductance value is determined by using the test reactor, the HSR is set (it is
adjustable) to the proper value and installed. Complete details on the theory of operation and method of
installation are available from the HSR manufacturer.
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