Product Search
Find the right transformer for your needs
Three Phase Autotransformers Series Three Phase Transformers
12 Models available
Images are for illustration purposes only
Three Phase Autotransformers — Step-Up / Step-Down 380V
General-purpose three-phase autotransformers step voltage up or down with a single winding that serves as both primary and secondary, offering higher efficiency and smaller size than equivalent isolating transformers. Rated 1–500 kVA for 380V/220V/110V systems, used for voltage conversion, interconnection and step-up applications.
Key Features
- Single-winding autotransformer design for high efficiency
- Step-up or step-down voltage conversion
- 1–500 kVA, 380V/220V/110V systems
- Smaller and lighter than isolating transformers
- Low no-load loss and low copper loss
- Custom voltage ratios available
Applications
- Voltage conversion and interconnection
- Motor starting voltage adjustment
- Test and laboratory power
- 380V step-up/down applications
TECHNICAL DRAWING
Model: OSG-80KVA | Type: Oil-immersed transformer | Capacity: 80 kVA
FRONT ELEVATION
ELECTRICAL SCHEMATIC
EFFICIENCY vs LOAD
SIDE VIEW
TOP VIEW
TERMINAL BLOCK
CORE & WINDING
LEGEND:
Specifications Range
All specifications and dimensions can be customized upon request
Model Selector
| Key parameters | Model Range |
|---|---|
| Capacity | 5–500 kVA |
| HV Voltage (kV) | 0.38 |
| LV Voltage (kV) | 0.4 |
| Frequency (Hz) | 50/60 |
| Impedance (%) | 4 |
| Cooling | AN |
| Efficiency | >97% |
| Standard | IEC 60076 / GB1094.1 |
| Connection | Dyn11 |
| Insulation class | F (155°C) |
| Allowed temperature rise | 100 |
| Noise level | 50 dB(A), 55 dB(A), 58 dB(A), 61 dB(A) |
| Tap Changer | ±5% |
| No-load loss | 61–765 W |
| Load loss | 380–4360 W |
| Compare | Model | Series | Capacity (kVA) | Input voltage | Output voltage | Frequency (Hz) | Rated current (A) | Weight | Dimensions |
|---|---|---|---|---|---|---|---|---|---|
| OSG-5KVA | Three Phase Autotransformers | 5kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 47 kg | 600×515×805 mm | |
| OSG-10KVA | Three Phase Autotransformers | 10kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 57 kg | 625×535×835 mm | |
| OSG-15KVA | Three Phase Autotransformers | 15kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 66 kg | 640×550×860 mm | |
| OSG-20KVA | Three Phase Autotransformers | 20kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 75 kg | 660×565×880 mm | |
| OSG-30KVA | Three Phase Autotransformers | 30kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 92 kg | 685×590×920 mm | |
| OSG-50KVA | Three Phase Autotransformers | 50kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 123 kg | 735×630×985 mm | |
| OSG-80KVA | Three Phase Autotransformers | 80kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 167 kg | 795×680×1065 mm | |
| OSG-100KVA | Three Phase Autotransformers | 100kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 195 kg | 830×710×1110 mm | |
| OSG-150KVA | Three Phase Autotransformers | 150kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 261 kg | 910×780×1215 mm | |
| OSG-200KVA | Three Phase Autotransformers | 200kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 324 kg | 975×835×1310 mm | |
| OSG-300KVA | Three Phase Autotransformers | 300kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 443 kg | 1095×940×1470 mm | |
| OSG-500KVA | Three Phase Autotransformers | 500kVA | 380V (3-phase) | customized ratio step-up/step-down | 50/60 | — | 664 kg | 1295×1110×1735 mm |
Selection Guide
Ratio
Confirm the input/output voltage ratio is moderate (autotransformers suit ratios near 1:1).
Capacity
Size to the continuous converted load.
- Frequently Asked Questions
What is a three-phase autotransformer?
An autotransformer uses a single winding for both primary and secondary, transferring part of the power conductively and part inductively — more efficient and compact than an isolating transformer for moderate voltage ratios.
How is it different from QZB starting autotransformers?
QZB autotransformers are dedicated to motor starting duty; general-purpose autotransformers serve continuous voltage conversion and interconnection.
Instant Selection & Quote Calculator
Select your specifications to get an estimated price instantly.
More options(2)
Certification
The values below are computed from what you selected above. Anything that cannot be computed yet is shown as an em dash — never as zero.
Iₙ = S / (√3·U) · I_sc = 100·Iₙ / uₖ · S_sc = √3·U·I_sc · I_p = k·Iₖ
Still required to complete the calculation: rated capacity S, impedance voltage uₖ, short-time or peak withstand current.
Per-model values (P0 / Pk / uₖ declared by the factory, losses, noise, temperature rise, dimensions, weight) are not in the product library: those rows stay at an em dash until the factory parameter sheet is supplied. An em dash means the value is unavailable — it is never rendered as zero.
Read-only: no price factor, not part of the sum — the loss-grade cost is already carried by the efficiency (subtype) base price, so charging here would double-bill. Values come from the product library type-test data, interpolated between published capacities; grades the library does not cover show an em dash, never zero.
Reference prices are for estimation only and do not constitute a formal offer.
3 · Get this quote
We will reply with your latest quote instantly.
Related Engineering Calculators
Free sizing and pricing tools for this product category.