TEDAŞ-MLZ/99-031.B Technical Specification for Cast-Resin Dry-Type MV/LV Distribution Power Transformers

Overview

This document is the technical specification issued by Türkiye Elektrik Dağıtım A.Ş. (TEDAŞ) for dry-type medium-voltage/low-voltage (MV/LV) distribution power transformers with windings encapsulated in epoxy resin. Its scope covers ratings up to 2 500 kVA. Because it contains no oil, this transformer type is the usual indoor choice in data center buildings, and the specification defines it through loss values, reference temperatures by insulation class and test requirements.

The loss provisions are the most useful part for design. Losses are guaranteed at a reference temperature set by insulation class: 120 °C for class F and 145 °C for class H. For the class up to 15.8 kV, the maximum permitted losses (no-load P0 / load loss Pk) are 1 550 W and 9 000 W for 1 000 kVA, 2 200 W and 13 000 W for 1 600 kVA, and 3 100 W and 19 000 W for 2 500 kVA.

In the 33 kV class the maximum losses are higher: for 1 600 kVA, P0 is 2 530 W and Pk 14 300 W, and for 2 500 kVA, P0 is 3 565 W and Pk 20 900 W. These values show that, at the same rating, the voltage class directly affects the loss budget when a transformer is chosen. Routine tests include no-load loss and current measurement, applied and induced voltage withstand tests and partial-discharge measurement, and these are to be carried out in accredited laboratories.

As for publication history, the first issue of the specification dates from April 1999 and the second update from April 2017. Related documents include IEC 60076-11, Article 65 of the Binaların Yangından Korunması Hakkında Yönetmelik (regulation on fire protection of buildings) and TEDAŞ-MLZ/99-032.E. As a limit, this is a grid operator's material specification; it contains no data-center-specific loading profile or total cost of ownership analysis. Such comparisons must be made separately by the designer.

Key points

1. Covers cast-resin dry-type MV/LV distribution transformers rated up to 2 500 kVA (clause 1.1).
2. Losses are guaranteed at a reference temperature by insulation class: class F 120 °C, class H 145 °C.
3. Maximum losses up to 15.8 kV: 1 000 kVA P0 1 550 W / Pk 9 000 W.
4. Up to 15.8 kV: 1 600 kVA 2 200 / 13 000 W; 2 500 kVA 3 100 / 19 000 W.
5. 33 kV class: 1 600 kVA P0 2 530 W / Pk 14 300 W; 2 500 kVA 3 565 / 20 900 W.
6. Routine tests: no-load loss and current, applied and induced voltage withstand, partial discharge; in accredited labs.
7. First issue April 1999, second update April 2017.

Using it in design

• Default indoor data center transformers to cast-resin dry type; no oil pit is needed under the fire regulation.
• Use these loss values as defaults and compare dry versus hermetic transformer life-cycle losses in the energy model.
• Choose with the voltage class in mind (15.8 kV versus 33 kV), since it affects the loss budget.
• Include routine tests and partial-discharge measurement in the procurement specification.

Who should read it

Data center electrical designers, substation engineers and procurement teams.

Related standards

• IEC 60076-11
• Binaların Yangından Korunması Hakkında Yönetmelik Madde 65
• TEDAŞ-MLZ/99-032.E

Publication details

Authors

Türkiye Elektrik Dağıtım A.Ş. (TEDAŞ)

Publisher

Türkiye Elektrik Dağıtım A.Ş. (TEDAŞ)

Year

2017

Document number

TEDAŞ-MLZ/99-031.B

Document language

Turkish

Source type

Turkish regulation

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation