Page 13 - Energize April 2022

NEWS

Choosing the right harmonic filter

he range and complexity environment in which it is going to run. If unsure, you should always refer to an expert.
of electrical and electronic Another option is a mixed solution. You could use a passive filter on some applications
Tequipment used in manufacturing and add a smaller active filter overall, which will help you save costs in the long run.
environments has increased dramatically
over the last few years. Here, John Excess heat?
Mitchell, global business development Another thing to consider when choosing a harmonic filter is that harmonic currents can
manager of supply, repair and field service induce additional heating in generators. Harmonics can also lead to heating of busbars,
specialist CP Automation explains how to cables and equipment and cause thermal damage to induction motors and generators and
manage the increasing harmonic levels in thermal tripping of safety devices, like fuses or sensors in breakers. These relatively minor
the modern industrial landscape. issues can have a negative effect on the entire system and can increase maintenance costs.
The introduction of variable Luckily, some active filters produce up to a third less heat than competitor products due
speed drives, fluorescent lighting and to the switching techniques of the insulated-gate bipolar transistors (IGBTs). Equally, the
transformers has brought a rise in the REVCON RHF Series of passive filters offer up to 99,5% efficiency.
number of non-linear loads. One of the When comparing filters, active or passive, you should look closely at the total cost
unwanted consequences of non-linear of ownership for the end user. After all, heat loss is a direct cost in energy bills. This is
loads is the creation of harmonic currents, particularly important on the shop floor, in marine and offshore applications or any other
which can cause voltage distortion and environments where space and heat is particularly precious.
quality problems. Before choosing a harmonic filter, it is important to assess the entire system and size the
To address the issues caused right solution for your specific needs. It is not enough to look at one troublesome application
by high harmonics levels, including individually. Instead, you should have an accurate representation of the entire operation as a
motor vibration, voltage notching, whole. Often what looks like the cause of a problem can actually be an effect.
electromagnetic interference and CP Automation suggests performing a plant survey and collecting data over several days.
overheating, companies can use harmonic After the initial analysis, we can recommend the most appropriate product and install it
filters. without significant disruptions.
Once the harmonic filter has been live for a few weeks, another survey is necessary to
Active or passive? check if all problems have been resolved. This ensures the product is appropriate and it gives
When choosing a harmonic filter, the first companies real peace of mind.
thing to consider is whether you need a Unfortunately, harmonics are not going anywhere, so businesses can’t afford to just
passive or an active one. The traditional ignore them. Instead, the best solution is to tackle the problem head on and if you are
choice is a passive filter, used to minimise unsure of anything, always consult an expert.
power quality problems in the network.
These filters operate mainly on a fixed Contact John Mitchell, CP Automation, john.mitchell@cpaltd.net, www.cpa-ltd.net
basis and are tuned to a harmonic order
close to the order to be eliminated. One
drawback of passive filters is that they are
most efficient when the load is operating
above 80 per cent and they cannot adapt
the amount of compensation current they
inject into the system.
On the other hand, active harmonic
filters are the most flexible solution on
the market. They monitor the network
and inject the necessary amount of
compensation current at any given time,
which restores current waveform and
lowers current consumption. This makes
them ideal for installations in which
current load changes constantly.
Regardless of what type of harmonic
filter you decide to use, make sure it
has the relevant UL certifications for the

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