When designing a transformer or
inductor, Talema deign engineers always ask what the application
is. Why is this ?
The application of a magnetic component can have significant
implications in determining the most suitable design. Common
applications would be :
Each of the above fields of
application have their own specific requirements for transformers
and inductors.
For example, a power transformer for use in Domestic
Audio Visual equipment would usually need to be designed using a
low flux-density in the core to reduce the radiated magnetic
field, have varnish impregnated core and windings to reduce the,
physical "noise", and be wound using very uniform winding
machines.
Depending on the equipment design, it may also
require a magnetic screen (known as a GOSS
Band) to reduce the
radiated magnetic field. Generally the transformer must be UL
recognised, and also conform the the requirements of EN60065
(IEC65) as a minimum.
Compare this to a toroidal power transformer for use
in Low Voltage Lighting (12V Halogen lighting, know as LVL):
The important points for a lighting transformer would be the
generated heat, the accuracy of the output voltage which affects
the life of the lamp(s), the effectiveness of the overload
protection device(s), and generally the physical space into which
the transformer must be mounted is very restricted. On top of all
this, the transformer must meet all the requirements of "short-cicuit
proof" according to EN61558 (replacing EN60742).
Consider a power transformer for use in Medical
equipment. There are requirements for the maximum permissible
leakage current which can flow from the mains supply to the earth
point, so the transformer generally
requires a higher level of insulation between the primary winding
and the earthed copper screen to ensure that the combination of
all the possible sources of leakage current (mains cable, input
socket, mains filter, transformer) remains within limits of
EN60601 (UL2601).
The transformer will also generally require a thermal fuse or
thermal switch of some type, which will switch off the power
supply if a fault condition occurs in the equipment.
As may be seen from the above comparisons, the "field of
application" of the transformer does indeed dictate certain design
criteria, which have an important effect on designing the most
suitable component.
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