HOW isolation transformer works.

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HOW isolation transformer works...

Answer / thowsif_emerson

An isolation transformer is a transformer, often with
symmetrical windings, which is used to decouple two
circuits. An isolation transformer allows an AC signal or
power to be taken from one device and fed into another
without electrically connecting the two circuits. Isolation
transformers block transmission of DC signals from one
circuit to the other, but allow AC signals to pass. They
also block interference caused by ground loops. Isolation
transformers with electrostatic shields are used for power
supplies for sensitive equipment such as computers or
laboratory instruments.

In electronics testing, troubleshooting and servicing, an
isolation transformer is a 1:1 power transformer which is
used as a safety precaution. Grounded objects near the
device under test (desk, lamp, concrete floor, oscilloscope
ground lead, etc.) may be at a hazardous potential
difference with respect to that device. By using an
isolation transformer, the bonding is eliminated, and the
shock hazard is entirely contained within the device.

Isolation transformers are also used for the power supply
of devices not on ground potential. A well-known example is
the Austin transformer for the power supply of air-traffic
obstacle lamps on mast radiators insulated against ground.

Isolation transformers are commonly designed with careful
attention to capacitive coupling between the two windings.
This is necessary because excessive capacitance could also
couple AC current from the primary to the secondary. A
grounded shield is commonly interposed between the primary
and the secondary. This greatly reduces the coupling of
common-mode noise present on supply conductors.

Differential noise can magnetically couple from the primary
to the secondary of an isolation transformer. This requires
other measures, such as a filter, to block differential
noise from the secondary of an isolation transformer.