Q: Kuv 50 kV / 5 kVA test transformer - tus thawj coj hais tias "tsuas yog txuas rau 3 km cable." Tej yam xav tias tsis ncaj ncees lawm. Kuv puas yog?
A: Koj hais yog lawm. Tsis txhob ua qhov no. Qhov no yog qhov # 1 pib yuam kev uas rhuav tshem transformers.
Teeb meem # 1: Loj heev
• 3 km 35 kV cable: C ≈ 0.5 μF. I_charge=50,000 × 314 × 0.5 × 10⁻⁶=7.85 A.
• Xav tau lub hwj chim: 50 kV × 7.85 A=393 kVA.
• Koj lub transformer yog ntsuas 5 kVA. Koj tab tom thov rau 78 × ntsuas lub zog. Lub winding yuav haus luam yeeb hauv vib nas this.
Teeb meem #2: Waveform distortion
• Capacitive load → coj lub hwj chim → transformer core saturates.
• Cov zis waveform ua peaked - crest factor nce ntawm 1.414 mus rau 1.6–1.8.
• Ib qho kev ntsuas 50 kV RMS yuav ua rau 90 kV ncov - tsis muaj kev tswj hwm kev ntxhov siab.
Teeb meem #3: Kev tswj hluav taws xob tsis ua haujlwm
• Thaum tsis muaj load, koj teem 50 kV.
• Thaum lub cable txuas, qhov hluav taws xob poob mus rau 10-20 kV (lub transformer tsis tuaj yeem muab tam sim no).
• Tig input → TX saturates ntau → voltages → fuses.
Thaum twg yog ib qho kev sim transformer ua haujlwm rau cables?
|
Cable ntawm 35 kV |
C |
Tam sim no @ 50 kV |
OK for 5 kVA TX? |
|
< 100 m |
< 15 nF |
< 0.24 A |
❌ Tseem 2.4 × overload |
|
< 50 m |
< 8 nF |
< 0.12 A |
❌ 1.2 × overload |
|
< 20 m |
< 3 nF |
< 0.05 A |
✅ Hauv kev ntsuas |
Txoj cai nyuaj: Tsuas yog siv lub tshuab hloov pauv rau cov cables luv dua ~ 25 meters. Rau ib yam dab tsi ntev dua, siv lub tshuab resonant.
Kev Taw Qhia Kev Xaiv Ceev
|
Yog koj xeem... |
Xaiv... |
Yog vim li cas |
|
CT, PT, bushing, luv luv bus bar |
Kuajtransformer |
Yooj yim, pheej yig, muaj zog txaus |
|
Switchgear / 1-2 GIS bays |
Kuajtransformerlos yog me me SR |
Ob leeg ua haujlwm |
|
Distribution cable <500 m |
Me me SR (30-60 kV) |
Xav tau Q-factor power saving |
|
HV kab> 1 km |
SR (100-300 kV) |
Tsuas yog kev xaiv siv tau |
|
Lub tshuab hluav taws xob stator |
SR (20-30 kV siab I) |
Clean waveform, siab tam sim no |
|
Transformer induced test |
SR nrog> 100 Hz |
Zaus > ntsuas xav tau |
|
Factory niaj hnub (tib yam load) |
Test TX or fixed SR |
Txheem xaiv |
|
Field test (cov loads sib txawv) |
Modular SR |
Flexibility rau reconfigure |