This preview shows pages 1–11. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: UCF Open Δ−Δ (or V−V) Connection VC = − V A − VB = −V∠ 0 o − V∠ − 120 o = V∠ + 120 o
This is exactly the same voltage that would be present if the third transformer Were still there. Phase C is sometimes called a ghost phase. UCF Voltage, Current and Power in a Δ −Δ Transformer Bank Maximum power that can supply to the resistive load: PΔ − Δ = 3Vφ I φ UCF Voltage, Current and Power in a VV Transformer Bank Maximum power that can supply to the resistive load:
PV −V = Vφ I φ cos( 0 o − ( − 30 o )) + Vφ I φ cos( − 120 o − ( − 90 o )) = Vφ I φ cos 30 o + Vφ I φ cos( − 30 o ) = 3Vφ I φ (from transformer)
3 /3 = 0 . 866 2/3 or PV − V = 3V φ Iφ 3 = 3V φ I φ
⇒ (from balanced 3phase load) 3 phase PV − V 3 = = 0 . 577 3 PΔ − Δ UCF Reactive Power of VV Transformers 3 Reactive power of transformer 1: 1 QTrans 1 = Vφ I φ sin( 0 − ( − 30 )) = Vφ I φ sin 30 = Vφ I φ 2 Reactive po er Reacti e power of transformer 2:
o o o 1 QTrans 2 = Vφ I φ sin( − 120 o − ( − 90 o )) = Vφ I φ sin( − 30 o ) = − Vφ I φ 2 UCF Open Y − Open Δ Connection p p Note the presence of neutral lead at the primary side. UCF Scott T Connection (3 Phase to 2 Phase) ( ) 3 = 0 . 866 2 UCF 3 Phase Scott T Connection UCF Magnetizing Current g g N P i P − N S i S = H ( B )l C = F NS iS ) N P i P − N S i S = N P (i P − NP NS Define : iM = iP − iS NP N P iM = H ( φ
Ac )lC = F(φ ) UCF Effects of Peak Flux on Magnetizing Current g g Saturated! I M ,rms 1 T 2 = ∫0 iM (t )dt T UCF Maximum Voltage g Steady State v P (t ) = 2V cos( ω t ) = N P d φ y (
dt 1 φ= NP ∫v P (t ) dt = 2V P , rms ωN P sin( ω t ) φ max = 2V P , rms 2πfN P 2πfN Pφ max ≈ 4 .44 fN P Bmax Ac 2πfN Pφ max ≈ 4 .44 fN S Bmax Ac V P , rms , max = V S , rms , max = UCF Voltage and Frequency Ratings g q y g VoltSecond Balance Vrms,max = 2πfNφmax ≈ 4.44 fNBmax Ac or : Vrms,max f = 2πNφmax ≈ 4.44NBmax Ac ...
View
Full
Document
This document was uploaded on 11/03/2009.
 Fall '09
 Volt

Click to edit the document details