what difference between thermal and bi-metal over load relay?

2 Answers  

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In Dyn11 power transformer if any one of the 3 phases connected to earth in star connected side then please explain effect of the current flow in delta connected side of transformer.(In this case if one phase is shorted to ground in star connected side then we observe the current flow in two phases only not three phases in delta connected primary side. Please explain why it is so?)

0 Answers  

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Why current transformers are rated in BURDEN instead of VA?

4 Answers   Bhel,

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WHAT IS THE USE OF PIG TAIL IN WINDOW CT ?

0 Answers  

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How can be decreased the size of transformer?

6 Answers  

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why we use perllel conection system in the wiring?

4 Answers   Airtel,

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On load tap changer (OLTC) explode? Transformer Vector group: Ynd11 Rated Power: 353MVA Rated Current: 693A Voltage:294/20KV OLTC Type: T III Y1000 110/c 12193w Max Operation Current: 295A Step Voltage: 550V Arrangement in Tx windings: Y Connection Problem: Damage of Unit 1 Generator Transformer On Load Tap Changer (OLTC) Description of Incident: 9.00 a.m. :- Generator No Load test on excitation system started 10.30 a.m :- Carried out AVR change over test 11.30 a.m :- Preparation for Generator Manual Synchronizing test 12.00 a.m :- Manual Synshronizing test started. Observed incoming generator voltage higher than running voltage. CECR operator operated Generator Transformer OLTC to bring down the incoming generator voltage 12.03 a.m :-Generator Transformer abnormal alarm operated at Gen.Control Desk (CECR) CECR operater at Generator transformer bay informed that the transformer oil splashed out from OLTC. CECR operater informed that he heard explosion inside OLTC. Observed Oil level & Oil Flow alaram operated at Tranformer local annunciator. 12.05 am :- CECR operator 'Open Gen Field Breaker” 12.10 a.m. :- Elec1 team inspected the OLTC and found the OLTC rupture disk was broken and oil spilled at OLTC area. - Elec1 found the OLTC top cover bulging. Do anyone know why and possibility cause happen in this OLTC.

9 Answers  

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why a pilot exciter is used in combination with the main exciter? why not only a main exciter is used for excitation to an alternator?

1 Answers   Electrical,

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What is rotating transformer? Which machine is used specifically as rotating transformer?

3 Answers   TATA,

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how we sesign the transformer give some specifion regarding design of transformers

0 Answers  

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I have an enquiry of develop solar power plant, 0.69/11kV, 1500kV/750/750kVA, Dy11y11 Transformer. I want to know what does 1500kV/750/750kVA means? Sorry if this is a noob question.

2 Answers  

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hi i wonder will the speed of a 50hz AC motor reduce if i supply it with 25hz?

4 Answers   Divis Laboratories,

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