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Isolation transformer
 
 
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An isolation transformer is a transformer
Transformer

A transformer is a device that transfers electrical energy from one electrical network to another through inductive coupling conductors — the transformer's coils or "windings"....
, often with symmetrical windings, which is used to decouple
Coupling (electronics)

In electronics and telecommunication, coupling is the desirable or undesirable transfer of energy from one Transmission medium, such as a metallic wire or an optical fiber, to another medium, including fortuitous transfer....
 two circuits. An isolation transformer allows an AC
Alternating current

In alternating current the movement of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again....
 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
Direct current

Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as battery , thermocouples, solar cells, and commutator-type electric machines of the dynamo type....
 signals from one circuit to the other, but allow AC signals to pass. They also block interference caused by ground loop
Ground loop (electricity)

In an electrical system, a ground loop usually refers to a current, generally unwanted, in a electrical conduction connecting two points that are supposed to be at the same potential, often ground , but are actually at different potentials....
s.






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Encyclopedia


An isolation transformer is a transformer
Transformer

A transformer is a device that transfers electrical energy from one electrical network to another through inductive coupling conductors — the transformer's coils or "windings"....
, often with symmetrical windings, which is used to decouple
Coupling (electronics)

In electronics and telecommunication, coupling is the desirable or undesirable transfer of energy from one Transmission medium, such as a metallic wire or an optical fiber, to another medium, including fortuitous transfer....
 two circuits. An isolation transformer allows an AC
Alternating current

In alternating current the movement of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again....
 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
Direct current

Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as battery , thermocouples, solar cells, and commutator-type electric machines of the dynamo type....
 signals from one circuit to the other, but allow AC signals to pass. They also block interference caused by ground loop
Ground loop (electricity)

In an electrical system, a ground loop usually refers to a current, generally unwanted, in a electrical conduction connecting two points that are supposed to be at the same potential, often ground , but are actually at different potentials....
s. 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. Since the neutral wire of an outlet is directly connected to ground, grounded objects near the device under test
Device under test

Device under test , also known as unit under test , is a term commonly used to refer to a manufactured product undergoing testing....
 (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 commonly designed with careful attention to capacitive coupling
Capacitive coupling

In electronics, capacitive coupling is the transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can be an intentional or accidental effect....
 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.

See also

  • Balun
    Balun

    File:Balun-twisted-pair-to-coaxial-hdr-0a.jpgA balun, , is a type of electrical transformer that can convert electrical Signalling s that are balanced line about ground to signals that are unbalanced line and vice versa....
  • Galvanic isolation
    Galvanic isolation

    Galvanic isolation is the principle of isolating functional sections of Electricity so that charge-carrying particles cannot move from one section to another, i.e....
  • Transformer types
    Transformer types

    A variety of types of electrical transformer are made for different purposes. Despite their design differences, the various types employ the same basic principle as discovered in 1831 by Michael Faraday, and share several key functional parts....
  • Power quality
    Power quality

    In its broadest sense, power quality is a set of boundaries that allows grid s to function in their intended manner without significant loss of performance or life....