EC
3205 – Electrical
Machines and Drives
TOPICS
UNIT I CIRCUITS
AND TRANSFORMERS
UNIT II ELECTRICAL MOTORS
UNIT
III SPEED CONTROL AND STRATING
UNIT IV ELECTRICAL DRIVES
UNIT
V SOLID STATE
DRIVES(QUALITATIVE TREATMENT ONLY)
UNIT
I-Electric Circuits and Transformer
1. State
Ohm’s law for magnetic circuit.
It
states that the magneto motive force across the magnetic element is equal to
the product of the magnetic flux through the magnetic element and the
reluctance of the magnetic material. It is given by MMF = Flux X Reluctance
2. Define
leakage flux
The
flux setup in the air paths around the magnetic material is known as leakage
flux.
3. Define
magnetic reluctance
The
opposition offered by the magnetic circuit for the magnetic flux path is known
as magnetic reluctance. It is analogous to electric resistance.
4. What
is fringing?
In
the air gap the magnetic flux fringes out into neighbouring air paths due to
the reluctance of air gap which causes a non-uniform flux density in the air
gap of a machine. This effect is called fringing effect.
5. Mention
some magnetic materials
Alnicos, chromium steels, copper–nickel alloy,
nickel, cobalt, tungsten and aluminium.Click Here to download the full documents