# BEST 40 MVA 154/6.3-6.3 kV Dual-Secondary Power Plant Auxiliary Service Transformer

> BEST 40 MVA 154/6.3-6.3 kV Dual-Secondary Power Plant Auxiliary Service Transformer belongs to the Oil-Immersed Conservator Transformers category and is rated at 40 MVA with 154/6.3 kV primary/secondary voltage. Application: 154 kV National Grid to 34.5 kV Main Step-Down Power Transformer. Final ratings must be verified against the manufacturer datasheet.

> SKU: VF-BST-AUX-40M-154 | Brand: BEST Transformatör | Category: Power & Energy Equipment / Transformers / Distribution Transformers / Oil-Immersed Conservator Transformers

**Voltformer canonical:** https://voltformer.com/product/best-40-mva-154-6-3-kv-power-plant-auxiliary-service-transformer - markdown version: https://voltformer.com/product/best-40-mva-154-6-3-kv-power-plant-auxiliary-service-transformer.md

## Overview

BEST 40 MVA 154/6.3-6.3 kV Dual-Secondary Power Plant Auxiliary Service Transformer is intended for 154 kV National Grid to 34.5 kV Main Step-Down Power Transformer. Configured electrical data: 40 MVA, 154/6.3 kV primary/secondary voltage, 50 Hz, 3-phase, vector group YNd11-d11 and short-circuit impedance 12.5%. Construction: Copper (Cu-Cu); cooling: ONAN/ONAF; loss class: Ecodesign Tier 2. 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:** 154 kV National Grid to 34.5 kV Main Step-Down Power Transformer
- **Target industries:** National Transmission Grid Network, Major Power Plants (Hydro & Wind), Mega Industrial Zone Grid Infeeds
- **Brand:** [BEST Trafo (Balıkesir Elektromekanik)](https://voltformer.com/brand/best-trafo.md) - Turkey's most established transformer manufacturer since 1966; BEST Trafo is the choice for global EPC projects with high-voltage power transformers up to 1000 MVA 525 kV, arc furnace transformers, TE
- **Category:** [Power & Energy Equipment](https://voltformer.com/catalog.md) / **Transformers** / [Distribution Transformers](https://voltformer.com/category/distribution-transformers.md): 50 kVA–3150 kVA oil-immersed hermetic, conservator and cast-resin dry-type medium-voltage distribution transformers. / [Oil-Immersed Conservator Transformers](https://voltformer.com/category/distribution-transformers/oil-immersed-conservator-tank-transformers.md)

## Technical Specifications

| Property | Value |
|---|---|
| Rated power | 40 MVA |
| Primary / secondary voltage | 154 kV / 6.3 kV (±8 x 1.25% (OLTC on-load tap-changing)) |
| Frequency / phases | 50 Hz / 3-phase - YNd11-d11 |
| Short-circuit impedance (Uk) | 12.5% |
| No-load loss P0 | 24.00 kW |
| Load loss Pk | 145.0 kW |
| Calculated efficiency (power factor = 1) | 99.5793% at 100% load; 99.6997% at 50% load |
| Loss class | Ecodesign Tier 2 |
| Windings | Copper (Cu-Cu) - cooling: ONAN/ONAF - insulation: Class A |
| Temperature rise | 65 K - sound pressure: 68 dB(A) |
| Mass and dimensions | 52000 kg - 6200×3800×4600 mm |
| Enclosure | IP55 / switchyard outdoor - wheel gauge: 1435 mm |
| LI / AC withstand | 650 kV peak / 275 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

- IEC 60076 series
- TEİAŞ technical specification
- TS EN 60076
- KEMA & CESI type-test approved

## Accessories

**Included:** Configuration-specific technical value, Configuration-specific technical value, Configuration-specific technical value
**Optional:** Online DGA, Configuration-specific technical value, Configuration-specific technical value

## Official sources

- https://www.besttransformer.com/

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

Manufacturer family/application source. BEST Transformatör üretimi santral yardımcı servis transformatörleri; termik, kombine çevrim ve hidroelektrik santrallerin iç tüketim baralarını bağımsız çift sekonder sargısıyla besler. Kesin empedans ve kayıplar santral tek hat projesine göre doğrulanmalıdır. 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 (On Request) - Indicative range: $420,000 – $510,000 USD
- Delivery time: 2–8 weeks (may vary depending on technical configuration, factory capacity and destination) - Warranty: 36 months
- Compliance candidates: IEC 60076 series, TEİAŞ technical specification, TS EN 60076, KEMA & CESI type-test approved. 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-BST-AUX-40M-154","quantity":1}]}
```

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