# Siemens Energy 250 MVA 400/154 kV Interconnection & Transmission Autotransformers (345-380 kV)

> Siemens Energy 250 MVA 400/154/33 kV tertiary-winding autotransformer engineered for national grid interconnection and reactive power control.

> SKU: VF-SIE-AUT-TER-250M-400 | Brand: Siemens Energy | Category: Power & Energy Equipment / Transformers / High-Voltage & Transmission Power Transformers / Interconnection & Transmission Autotransformers (345-380 kV)

**Voltformer canonical:** https://voltformer.com/product/siemens-energy-250-mva-400-154-33-kv-tertiary-autotransformer - markdown version: https://voltformer.com/product/siemens-energy-250-mva-400-154-33-kv-tertiary-autotransformer.md

## Overview

Siemens Energy 250 MVA 400/154 kV Interconnection & Transmission Autotransformers (345-380 kV) is intended for TEİAŞ 380 kV National Grid Backbone Main Interconnection Substation. Configured electrical data: 250 MVA, 400/154 kV primary/secondary voltage, 50 Hz, 3-phase, vector group YNa0d11 and short-circuit impedance 12.5%. Construction: Copper (Cu-Cu); cooling: ONAN/ONAF; loss class: TEİAŞ 380 kV İletim Standardı. These values support preliminary engineering selection; verify insulation levels, thermal limits, short-circuit duty, installation conditions and applicable standards against the manufacturer datasheet and the site study.

- **Application:** TEİAŞ 380 kV National Grid Backbone Main Interconnection Substation
- **Target industries:** National Transmission Grids, Mega Power Station Switchyards
- **Brand:** [Siemens Energy](https://voltformer.com/brand/siemens-energy.md) - The embodiment of German engineering excellence; Siemens Energy sets the industry standard with GEAFOL® cast-resin dry-type transformers, ester-oil network units and transmission-level autotransformer
- **Category:** [Power & Energy Equipment](https://voltformer.com/catalog.md) / **Transformers** / [High-Voltage & Transmission Power Transformers](https://voltformer.com/category/power-transmission-transformers.md): 5 MVA–1000 MVA 110 kV, 154 kV, 380 kV, 500 kV and 1000 kV UHV AC/DC transmission and interconnection power transformers. / [Interconnection & Transmission Autotransformers (345-380 kV)](https://voltformer.com/category/power-transmission-transformers/interconnected-grid-autotransformers.md)

## Technical Specifications

| Property | Value |
|---|---|
| Rated power | 250 MVA |
| Primary / secondary voltage | 400 kV / 154 kV (±12 x 1.25% OLTC) |
| Frequency / phases | 50 Hz / 3-phase - YNa0d11 |
| Short-circuit impedance (Uk) | 12.5% |
| No-load loss P0 | 70.00 kW |
| Load loss Pk | 440.0 kW |
| Calculated efficiency (power factor = 1) | 99.7964% at 100% load; 99.8562% at 50% load |
| Loss class | TEİAŞ 380 kV İletim Standardı |
| Windings | Copper (Cu-Cu) - cooling: ONAN/ONAF - insulation: Class A |
| Temperature rise | 65 K - sound pressure: 68 dB(A) |
| Mass and dimensions | 188000 kg - 9400×5200×6900 mm |
| Enclosure | IP55 - wheel gauge: 2000 mm |
| LI / AC withstand | 1425 kV peak / 630 kV rms - partial discharge: 5 pC |
| Environment | -25°C / +40°C; altitude ≤ 1000 m |
| Core steel | CRGO Laser-Treated Grain-Oriented Silicon Steel (23ZDMH85 / Baosteel B23R085) |
| Bushings / terminals | Direct Copper Busbar Terminals (Busbar Integrated / IP00-IP31) |

## Standards

- TEİAŞ technical specification
- IEC 60076
- TS EN 60076

## Accessories

**Included:** Reinhausen Vacuum OLTC, Online DGA 9-Gas Analyzer, Buchholz Relay
**Optional:** Fiber Optic Direct Winding Temperature Sensor

## Official sources

- https://www.siemens-energy.com/global/en/home/products-services/product-offerings/transformers/power-transformers.html
- https://www.siemensenergy.com/global/en/home/products-services/product-offerings/transformers.html

- **Source scope:** manufacturer-family
- **Last reviewed:** 2026-09-13

Manufacturer family/application source. Siemens Energy transmission autotransformers for 400 kV interconnected networks feature delta tertiary stabilizing windings configured for substation shunt reactors or dynamic reactive compensation systems. Exact order code, guaranteed losses, dimensions, insulation level, cooling stage, winding material and project options must be confirmed with the OEM before procurement or an SLD study.

## Pricing & Logistics

- Pricing type: RFQ (Project Engineering) - Indicative range: $1,100,000 – $1,350,000 USD
- Delivery time: 2–8 weeks (may vary depending on technical configuration, factory capacity and destination) - Warranty: 48 months
- Compliance candidates: TEİAŞ technical specification, IEC 60076, TS EN 60076. Verify applicability and conformity against the exact offered model and project jurisdiction.

## RFQ

Request a formal factory quotation via Voltformer RFQ:

```json
POST https://voltformer.com/api/v1/rfq
{"companyName":"Example Energy","email":"procurement@example.com","items":[{"skuOrId":"VF-SIE-AUT-TER-250M-400","quantity":1}]}
```

Full catalog JSON: https://voltformer.com/agent-catalog.json - OpenAPI: https://voltformer.com/openapi.json