Date: August 2012
Company: Enersis / Santiago – Metropolitan area.
CH Three Phase autotransformer, auto refrigerated, immersed in mineral oil, outdoors, hermetic, with insulators class 34,5kV to high voltage, designed and constructed according to ANSI C 571290 norms.
1) Autotransformer general characteristics
- Potential: 2000 kVA
- Raise of temperature: 65 ºC
- Service altitude: 1000 m.a.s.l.
- Frequency: 50 Hz
- Impedance: 4%; tolerance ± 10 %
- Connection group: Yyn0
- Polarity: Subtractive
- Nº of phases: 3
- Nominal primary voltage: 23000 Volts
- Primary BIL: 150 kV
- Autotransformer Connection: Three Phase
- Secondary voltage: 12000 Volts
- Secondary BIL: 95 kV
- Primary derivations: 25300-24150-23000-21850-20700 Volts
- Tertiary voltage: < 5 kV
- Tertiary connection group: Closed delta with accessible vertex.
- Refrigerant liquid: Dielectric mineral oil
- Refrigeration: ONAN
- K Factor: 1
- Losses: Normal
2) Tests to the autotransformer
Routine tests indicated in ANSI C57.12.90 were realized, and the sealing and pressure proves.
3) Autotransformer accessories
- Bushings located on the lid
- Tap changer, external drive, no voltage
- Oil level indicator magnetic-type
- Oil temperature thermometer dial-type, with drag needle
- 1” oil full nipple in the cover
- Above valve of 1” oil filtrated
- Valve of draining and exposing 1”
- Pressure relief valve
- Tertiary bushings accessible to bridge with fuse
- Two plates of grounding connection
- Eyebolts
- Steel characteristic plate
- Dielectric mineral oil
- Anchor base to floor or platform
4) Autotransformer losses
- Loss in Cu: ≤ 11550 Watts
- Loss in Vació: ≤ 1890 Watts