TRANSFORMER INRUSH EFFECTS STUDIES DOWNLOAD LINK

DOWNLOAD LINK OF STUDIES ON TRANSFORMER INRUSH EFFECTS
Transformer Inrush Studies Link


Introduction
In a typical UK wind farm a series of radial 33kV collector circuits run from the main switchboard and link together individual wind turbine generator (WTG) transformers. At the design stage it is necessary to determine the maximum number of WTG transformers that can be energised simultaneously from the 33kV system.

One of the factors to be considered is the voltage dip experienced at the point of common coupling (PCC) or interface between the electrical system of the wind farm and the utility company. The UK standard applied is the Electricity Council’s Engineering Recommendation P28, which allows a 3% voltage dip. This article describes wind farm transformer inrush analysis studies the Glasgow based power systems consultants Mott MacDonald have undertaken using PSCAD to demonstrate compliance with P28.

Transformer inrush
When a transformer is energised, it may draw a high magnitude transient current from the supply causing a temporary voltage dip. This current, characterised as being almost entirely unidirectional, rises abruptly to its maximum value in the first half-cycle and then decays until the normal steady-state magnetizing conditions are reached. The magnitude and duration of the inrush current depends upon the following all of which can be represented using a PSCAD model:

the point on the voltage wave at the instant the transformer is energised (i.e. switching angle);
the impedance of the supply circuit;
the value and sign of the residual flux linkage in the core;
the non-linear magnetic saturation characteristic of the core.

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DISTRIBUTION TRANSFORMER TECHNICAL SPECIFICATION EXAMPLE DOWNLOAD LINK

TECHNICAL SPECIFICATIONS OF DISTRIBUTION TRANSFORMER LINKS
Technical Specifications Distribution Transformer

DISTRIBUTION TRANSFORMER SAMPLE SPECS FROM INDIA


2.1 All equipment and material shall be designed manufactured and tested in accordance with the  latest applicable Indian Standard. IEC standard and CBIP manuals except where modified  and / or supplemented this specification.

2.2. Equipment and material confirming to any other standard, which ensures equal or better  quality, may be accepted. In such case copies of English version of the standard adopted  shall be submitted.

2.3. The Transformer offered shall in general comply with the latest issues including amendments  of the following Indian standards but not restricted to it.

3. System Description:
The distribution transformers shall be installed at outdoor/indoor location along 11 kV  distribution networks, which consists of both underground and overhead network. The HV  winding would be connected to SFU/OCB/VCB of the ring main unit through 11 kV (E)  XLPE/PILC cable. LV winding would be connected to switch type Fuse section pillar through 1.1  kV 1c, 400 sq mm XLPE cable.

4. Design Criteria:
4.1. The transformers shall be installed in hot, humid tropical atmosphere. All equipment  accessories and wiring shall be provided with tropical finish to prevent fungus growth..

4.2. The transformers shall be capable of continuous operation of rated output under the operating conditions of voltage and frequency variations as per statutory limits governed by relevant  Indian Standard and Electricity Act-2003 and its amendments in force.

4.3. The transformer shall conform to best engineering practice.

4.4. The design material construction shall be such that to secure reliability, economy, safe and  convenient operation and shall include   all specified or unspecified incidental items  necessary for similar equipment for convenient working in every respect.

4.5. The transformers shall be capable of withstanding the short circuit stresses due to terminal  fault between phase to phase and phase to ground on one winding with full voltage  maintained on the other windings for a minimum period of three seconds.

4.6. The transformers shall be free from annoying hum or vibration. The design shall be such as  not to cause any undesirable interference with radio or communication circuits.

4.7. Atmospheric Condition: The equipment offered shall be suitable for continuous satisfactory  operation in following prevailing climatic conditions.

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