Various EMI Sources
The EMI (electromagnetic interference), or the noisy disturbances which may hamper
any electronic circuit can be produced from various sources, such as ac motors,
fluorescent bulbs/ballasts, light dimmers, microwave ovens, microprocessors, computers,
and switch-mode power supplies. This noise can also be in the various types, like
the conducted EMI, radiated EMI, also known as the RFI.
In any power circuit, the EMI filter works to keep any kind of the disturbance generated
within the path, and to prevent the device from any external ac line noise. They
actually comprise of a network of so many interconnected components, including both
capacitors and inductors. As the basic work of EMI filters is to control emissions,
the case when the unwanted EMI are of very high frequencies, the filter works by
blocking the unwanted frequencies selectively.
Types of Noises
The noisy disturbances that may hamper power supply are of multiple types, for which
an EMI filter can work efficiently. The basic one is the conducted EMI, which is
of 2 types, common mode noise, and differential mode, which are known as CMN and
CMN is a kind of asymmetrical or line-to-ground noise, which exists on both sides
of the ac input. Here, the current flows in the same direction of both power conductors.
While, DMN is a kind of symmetrical or line to line noise, where the current flows
along one ac conductor and returns along the other. CMN can be suppressed with the
Y- capacitors and inductors, while the DMN suppression is done with the X-capacitors,
along with the inductors if the DMN is very high.
Other is parasitic noise which can be transferred within a circuit through an unexpected
means. This kind of noise gives contribution to both the above, symmetrical and
differential mode noise.
Use EMI EMC filters when some extra filtering is required
There are few cases where some extra noise has been produced rather than the level
which has been controlled. Also, at most of the time, some other filter is needed
as the level of noise is so high. This extra noise can be a sudden burst of energy,
which can be in either natural or man- made form. In such cases, an external or
auxiliary EMI filter has been installed, to bring the electrical noise down to acceptable
Like EMI, EMC or Electromagnetic Compatibility is also an important term which can disrupt the operation of an electronic device when being in the vicinity of an electromagnetic field. It describes how good a system work in an electromagnetic environment without putting in noisy emissions that can hamper a power line. There are varied frequency levels with which filter designs and attenuation power also varies and lead to better performance.
Types of EMI Filters
There are a wide range of sorts of EMI filters. At BLA we stock large portions of
the most widely recognized sorts categorized by type, case size / measurement, impedance,
greatest DC resistance and rated current. The parametric filters on our site can
help refine your search results relying upon the required specifications.
Most of the electrical devices are affected by EMI and there are so many sources
for it that includes motors, microprocessors, fluorescent bulbs, computers etc.
There may be some extra requirement few times, when the noise level is really high
and cannot be controlled by a single filter, and an additional filter is required.
In such cases, an auxiliary EMI is attached to put the noise level down to desired
The most widely recognized qualities for capacitance are 100 pF, 470 pF, 1 NF, 2.2
NF and 22 NF. We likewise convey EMI filters with capacitance up to 27 µF. Rated
current can have a extent between 1 MA and 100 A, with the most well known EMI filters
having a rated current of 200 MA, 300 MA, 2A or 6 A.
Applications for Electromagnetic Interference Filter:
Choosing the Right EMI Filter:
In the event that the amount of EMI filter that you require is not as much as a
full reel, we offer our clients a large number of our EMI filter products in tube,
tray or individual quantities that will help you stay away from unneeded excess.
In addition, BLA offers customers an exceptional bonded stock program that is intended
to eliminate potential issues that could emerge from an unpredictable supply of
products containing raw metals and products with long or unpredictable lead times.
Talk with your closest BLA ETECH branch and figure out all the more on how you
can keep away from possible shortages