Traction transformers for AC substations: Scott, Roof-delta, autotransformers
Traction transformers are installed at substations of AC electrified railways, including high-speed lines. They step the 132–220 kV grid voltage down to the traction network voltage and reduce the unbalance introduced by the single-phase load. The range covers Scott transformers, Roof-delta transformers and AT-system autotransformers.
- Scott transformer
- 220/27.5 × 2 kV and 132/27.5 × 2 kV; 60 / 80 / 100 MVA; ONAN / ONAF / OFAF
- Overload
- 150 % 15 min, 200 % 5 min (at ONAN)
- Roof-delta
- 220 / 60 × 2 kV, 120 MVA, ONAN, 300 % 2 min
- Autotransformer
- 60/30 kV, 10 MVA rated (own) capacity, 20 MVA through capacity, ONAN, 300 % 2 min
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Traction transformers are intended for substations of AC electrified railways, including high-speed ones. They step the 132–220 kV supply voltage down to the traction network voltage and reduce the unbalance of the three-phase grid caused by the single-phase traction load. The type and design are selected to the customer's requirements for voltage, power, losses and installation conditions.
The Scott-connected transformer converts three-phase voltage into two single-phase voltages with a phase shift of 90°. It is built as 220/27.5 × 2 kV or 132/27.5 × 2 kV for 60, 80 or 100 MVA with ONAN, ONAF or OFAF cooling. Overload at the ONAN rating is 150 % for 15 min and 200 % for 5 min. The standards are JEC, IEC and GB. A transformer with the Roof-delta connection also reduces unbalance. An example design of 220 kV / 60 kV × 2 for 120 MVA with ONAN cooling allows an overload of 300 % for 2 min.
Autotransformers are intended for the AT (autotransformer) feeding system, which reduces the voltage drop in the overhead contact line and electromagnetic interference. The typical 60/30 kV design has a rated (own) capacity of 10 MVA, a through capacity of 20 MVA and ONAN cooling. Short-circuit impedance is low, and thermal and mechanical withstand is designed for 25 or 35 times the rated current. Variants are available with mineral oil, vegetable oil, liquid silicone, gas (SF₆) and cast epoxy insulation.
The transformers are built at the manufacturer's plants in Hamakawasaki (Kawasaki) and Mie. They have been supplied for the Western Dedicated Freight Corridor (India), the traction substations of Taiwan High Speed Rail and the substations of the ROCA line (Argentina). They are used at traction substations and sectioning posts of 25 kV / 2 × 25 kV railways, on high-speed main lines and on freight corridors.
Technical specifications
| Scott transformer | 220/27.5 × 2 kV and 132/27.5 × 2 kV; 60 / 80 / 100 MVA; ONAN / ONAF / OFAF |
|---|---|
| Overload | 150 % 15 min, 200 % 5 min (at ONAN) |
| Roof-delta | 220 / 60 × 2 kV, 120 MVA, ONAN, 300 % 2 min |
| Autotransformer | 60/30 kV, 10 MVA rated (own) capacity, 20 MVA through capacity, ONAN, 300 % 2 min |
| Short-circuit withstand | 25 or 35 times the rated current |
| Standards | JEC, IEC, GB |
Replacement for
ТДТНЖ-25000/110, ТДТНЖ-40000/110, ТДТНЖ-40000/220, ТМЖ-400/27,5; Scott and Roof-delta have no direct analogue
selected by purpose and main parameters, please confirm with our manager
Request a price and lead time
Traction transformers for AC substations: Scott, Roof-delta, autotransformers. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
What power ratings and voltages does the Scott transformer have?
Designs of 220/27.5 × 2 kV and 132/27.5 × 2 kV with a rating of 60, 80 or 100 MVA. Cooling is ONAN, ONAF or OFAF.
What overload do the traction transformers allow?
The Scott transformer at the ONAN rating withstands 150 % for 15 min and 200 % for 5 min. For the 120 MVA Roof-delta and the 60/30 kV autotransformer, 300 % for 2 min is stated.
Which feeding systems are the autotransformers intended for?
For the AT system on 25 kV / 2 × 25 kV lines. The 60/30 kV design has a rated (own) capacity of 10 MVA, a through capacity of 20 MVA and withstand of 25 or 35 times the rated current.
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