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Protection of Alternator and Transformer
Protection of Alternator:
Alternator protection is critical to ensure the safe and
reliable operation of generators. Several protective schemes are employed to
safeguard alternators from faults and abnormal operating conditions:
- Overcurrent
Protection:
- Detects
excessive current due to short circuits or overloads.
- Uses
relays to trip the generator's circuit breaker.
- Differential
Protection:
- Compares
currents entering and leaving the alternator winding.
- Trips
the generator if there's a difference, indicating an internal fault.
- Stator
Earth Fault Protection:
- Monitors
the insulation of the alternator's stator winding against earth.
- Trips
the generator when a fault to earth is detected.
- Overvoltage
and Undervoltage Protection:
- Ensures
the alternator operates within safe voltage limits.
- Trips
the generator if voltage goes beyond or falls below set thresholds.
- Loss
of Field Protection:
- Detects
loss of excitation voltage.
- Prevents
generator operation without proper field excitation.
Protection of Transformer:
Transformer protection is crucial as transformers are vital
components in electrical networks. The following protective schemes are used to
safeguard transformers:
- Differential
Protection:
- Monitors
current entering and leaving the transformer windings.
- Detects
internal winding faults and trips the transformer.
- Buchholz
Relay Protection:
- Detects
gas accumulation due to internal faults like short circuits.
- Trips
the transformer and gives an alarm.
- Overcurrent
Protection:
- Protects
transformers against overloads and short circuits.
- Uses
time-current curves to trip the transformer.
- Overvoltage
and Undervoltage Protection:
- Monitors
the transformer's voltage to prevent insulation breakdown.
- Trips
the transformer if voltage exceeds or falls below set limits.
- Oil
Temperature Protection:
- Monitors
the oil temperature to prevent overheating.
- Trips
the transformer if oil temperature rises excessively.
- Pressure
Relief Device Protection:
- Protects
against internal faults causing pressure buildup in the transformer tank.
- Activates
pressure relief valves to release excess pressure.
- Earth
Fault Protection:
- Detects
earth faults in the transformer windings.
- Trips
the transformer to prevent further damage.
- Winding
Temperature Protection:
- Monitors
the winding temperature using embedded sensors.
- Trips
the transformer if winding temperature exceeds safe levels.
Importance:
Effective protection of alternators and transformers is
crucial for the stability and reliability of power systems. Faults in these
components can lead to extensive damage, disruption of supply, and even
catastrophic events. Proper selection and application of protective relays and
schemes are essential to ensure the safety and longevity of alternators and
transformers.