Transformer Design & Design Parameters

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Transformer Design & Design Parameters

Transcript Of Transformer Design & Design Parameters

Transformer Design & Design Parameters
- Ronnie Minhaz, P.Eng.
Transformer Consulting Services Inc.

Power Transmission + Distribution

GENERATION

TRANSMISSION

115/10 or 20 kV 132 161 230 345 500
Generator Step-Up transformer

SUB-TRANSMISSION
500/230 345/161 230/115 230/132
Auto-transformer

DISTRIBUTION DISTRIBUTED POWER

230/13.8 161 132 115
69 34
Step-down transformer

pads

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Standards
U.S.A.
• (ANSI) IEEE Std C57.12.00-2010, standard general requirements for liquidimmersed distribution, power and regulation transformers
• ANSI C57.12.10-2010, safety requirements 230 kV and below 833/958 through 8,333/10,417 KVA, single-phase, and 750/862 through 60,000/80,000/100,000 KVA, three-phase without load tap changing; and 3,750/4,687 through 60,000/80,000/100,000 KVA with load tap changing
• (ANSI) IEEE C57.12.90-2010, standard test code for liquid-immersed distribution, power and regulating transformers and guide for short-circuit testing of distribution and power transformers
• NEMA standards publication no. TR1-2013; transformers, regulators and reactors
Canada
CAN/CSA-C88-M90(reaffirmed 2009); power transformers and reactor; electrical power systems and equipment
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Transformer Design:
• Power rating [MVA] • Core • Rated voltages (HV, LV, TV) • Insulation coordination (BIL, SIL, ac tests) • Short-circuit Impedance, stray flux • Short-circuit Forces • Loss evaluation • Temperature rise limits, Temperature limits • Cooling, cooling method • Sound Level • Tap changers (DTC, LTC)
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Transformer Design: Simple Transformer
• Left coil - input (primary coil)
– Source – Magnetizing current
• Right coil - output (secondary coil)
– Load
• Magnetic circuit
Transformer Consulting Services Inc.

Transformer Design:
Power rating [MVA]
Power rating S [MVA] for three-phase transformer is defined as:
Where: U - rated line voltage (primary or secondary), I - rated line current (primary or secondary).
Transformer Consulting Services Inc.

Transformer Design:
Power rating [MVA]
• 30/40/50 MVA corresponding to different cooling stages, e.g. ONAN/ONAF/ONAF (OA/FA/FA), 0.6/0.8/1.0 p.u.
• 60/80/100//112 MVA for 55/65oC temperature rise units; 12% increase in power rating for 65oC rise from 55oC rise,
• 24/12/12 MVA for three-circuit units (e.g. HVLV1-LV2).
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Transformer Design:
Core Form
• Concentric windings • ‘Set’ Winding Geometry • Cooling options • Cost consideration • Shipping differences
Transformer Consulting Services Inc.

Transformer Design:

Type of Cores

Type 1 Type 2

– 3 legs
• 1 wound leg • 2 return legs
– legs and yokes not of equal cross section
– single-phase – 2 legs
• 2 wound legs
– legs and yokes of equal cross section – single-phase

Type 3

– 3 legs
• 3 wound legs
– legs and yokes of equal cross section – three-phase
Transformer Consulting Services Inc.

Transformer Design:
Type of Cores

Type 4

– 4 legs
• 2 wound legs • 2 return legs
– legs and yokes not of equal cross section
– single-phase

Type 5

– 5 legs
• 3 wound legs • 2 return legs
– legs and yokes not of equal cross section
– three-phase

Transformer Consulting Services Inc.
Transformer DesignYokesMvaPower RatingCoil