Supply of a new 30 MVA, ONAN, Yd1, 33/11 kV, 22.4% impedance export transformer

Concepts

• voltage transformers
• 22.4% impedance export transformer
• the existing original transformer
• two export transformers
• an export transformer
• the transformer tank
• the transformer foundation
• the transformer connections
• this new transformer
• new

Location

LONDON

Description

There are two export transformers in service at the site, both were manufactured by Ferranti In 1968. Each transformer is complete with an on-load tap-changer comprising 19 taps, with tap 13 being nominal tap. The voltage range is 39.6 kV to 29.7 kV with 1.67% taps. The transformer connections are bushings at 33 kV and cable at 11 kV. The services are for the design, manufacture, testing, and delivery to site of an export transformer for the Edmonton EfW plant in London. This new transformer and associated marshalling kiosk will replace the existing original transformer and marshalling/control panel.

Total Quantity or Scope

The services supplied shall encompass the supply only of a two winding transformer and of core type construction. All windings shall be fully insulated.The core, framework, clamping arrangements, windings, leads .and general structure of the transformer shall be of robust design capable of withstanding shocks to which it may be subjected during normal transport, Installation and service. The transformer shall be provided with a tap-changer. The tapping windings shall be so arranged as to preserve, as far as possible, the electromagnetic balance at all voltage ratios and shall also be arranged with due regard to any impulse voltage which may be impressed on the windings. The design shall ensure minimum variation in the Impedance from maximum tap to minimum tap. The tap-changer shall be fitted to the neutral end of the high voltage winding. The design of the tap· changer shall not produce significant displacement of the voltage vectors. Tap position indication shall be provided locally and available remotely. A lifting device shall be provided for removal of the tap-changer. Means shall be provided for lifting of the core and windings of the transformer. The terminal arrangements and connections shall not restrict access for normal maintenance and inspection purposes. All links contained within the transformer tank for earthing and other purposes shall be readilly accessible. Anti-vibration mountings shall be fitted between the tank and the transformer foundation. The terminations shall be rated to carry the maximum current at the minimum voltage of the respective winding.

Award Detail

CPV Codes

• 31172000 - Voltage transformers

Indicators

Legal Justification

In accordance with s32(2)(b) of the Public Contracts Regulations 2015, this contract was awarded to the successful bidder due to absence of competition due to lack of technical expertise. A fully compliant open procedure competitive tender was run to which the Contracting Authority did not receive any compliant bids. It follows that the contract was procured under the s32 negotiated procedure without prior notification.