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www.GEMultilin.com
140
www.GEMultilin.com
140
Transformer Principles
T
ransformer Pr
ot
ection
www.GEMultilin.com
www.GEMultilin.com
Introduction
The purpose of a transformer is to isolate, phase-shift, and step-up
or step down voltage and current levels for either distribution or
transmission. They perform these functions with the use of a primary
winding and one or more secondary windings located within the
transformer casing.
These windings work on the principle of induction, were the primary
winding induces the secondary winding(s) with voltage and current.
The windings are placed in close proximity, but are electronically
isolated from each other.
The power induced into the coils can either be stepped-down,
meaning an increase in current and a decrease in voltage, usually
required for distribution, or stepped-up meaning a decrease in
current and an increase in voltage, usually required for
transmission.
Transformers can range in size from very small coupling transformers
that are hidden within a device to large units that are used to
interconnect power grids. Transformers have become an essential
component for high voltage power transmission as they ensure long
distance transmission is economically practical.
Transformer Principles
Medium - High Voltage
Step-Up Transformer
100 MVA +
High Voltage
Step-Down Transformer
7500 kVA - 100 MVA
Primary
Winding
Oil-Cooling
Radiators
Steel
Laminations
Secondary
Winding
Oil Coolant
Medium - High Voltage
Step-Down Transformer
500 kVA - 7500 kVA
Medium - Low Voltage
Step-Down Transformer
75 kVA - 500 kVA
Typical Step-Down Distribution
Transformer
Transformer locations in a power system: