Transformer Protection Flashcards

1
Q

Features of HRC fuse

A

Used in MV TR
Oil and Gas
Load current flows through it

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2
Q

Fault clearing mechanism of HRC fuse

A

Fault current blows the fuse releasing the striker pin which hits the fuse switch tripping mechanism

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3
Q

Components of Transformer protection (TLF)

A

CT on each phase
2 OC coiks
1 EF coil
TLF parallel w/ O/C coils

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4
Q

Fault process in TLF transformer

A

In O/C:
Fuses will blow, fault pass through O/C coil
In E/F:
Ln will not be 0, fault current pass through E/F coil

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5
Q

About Restricted Earth Fault

A

Transformer internal fault protection
Differential relay
CTs connected to all phases and neutral of TR

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6
Q

About Stand By E/F

A

TR instantaneous protection
CT connected to TR neutral
Current over a set threshold will trip it

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7
Q

About Pressure Relief Valve

A

Protection against overpressure caused by internal fault

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8
Q

About Buchholz Relay

A

Gas relay
Connected b/w main tank and conservator of TR
Has two limit switches that move based on amount of air in oik

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9
Q

Types and limits of TR temperature relays

A

Oil temperature: triggers at 85C, trips at 90C
Winding temperature: triggers at 100C, trips at 110C (cooling system triggers at 65C)

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10
Q

About TR differential relay

A

HV TR relay, detects internal fault on both sides of TR

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