25-05-2012, 03:08 PM
transformer
condition_monitoring_transformers.ppt (Size: 1.02 MB / Downloads: 627)
Working principle of a transformer
A transformer is static (or stationary) piece of apparatus which:
1.Transfers electric power from one circuit to another.
2.It does so without a change in frequency.
3.The principle is based on mutual induction between two circuits linked by a common magnetic flux.
Basic parts of a transformer
Basically a transformer consists o f a :
1.A primary coil or winding.
2.A secondary coil or winding.
3.A core that supports the coils or the windings
Transformer construction
Main constructional elements of Transformers are -
A) Magnetic circuit Core & clamping structure
B) Electric Circuit Winding,Insulation, Bracing devices.
C) Terminals Tapping, Tapping switches, Terminal
Insulator, Leads , Bushings
D) Tank Oil, Cooling devices, conservator, piping,
Breather
E) Protective Circuit Buchholz relay, WTI, OTI, Oil surge relay
& Monitoring pressure relief device, MOG
Transformer construction
A)Magnetic Circuit:
The core provides closed path for flux. It is made up of CRGO insulated laminations. (CRGO has iron loss of about 1.3 W / Kg at 1.6 Tesla )
B)Electric Circuit:
Winding, insulation & bracing are constructional parts of electrical circuit of transformers. This is the most vulnerable part of transformer because of direct association with power system. Must be designed to withstand voltage stress resulting from system fault, transient over voltage and thermal stresses (lightening or switching surges)