Transformers; Project Rauhalahti 2026

Specifications for the 2 x 110/20 kV / 63MVA transformers Construction •The transformer shall be delivered complete with all normal parts and accessories. •required for proper performance and transport, including those not explicitly mentioned in the specification. •The thermometers and oil level indicator shall be placed so that these can be read from the ground levels. •Each alarm and trip contact of the protective equipment shall be electrically separated from any other contact. The continuous current carrying capacity of the contacts shall not be less than 0.5 A, and the breaking and making capacities shall not be less than 0.2 A (L/R = 40 ms) at 250 v Do. Transformer type •Air-cooled Oil transformer 3 phase. •Cooling method ONAN (ONAF as option). •Load will be at nominal load many hours per day. Nominal values •Nominal power (in all adjustment positions) 63 MVA ONAN. •Nominal voltage 117 ± 9 x 1.67/ 20 kV. •Frequency 50Hz.•Short circuit impedance 10-12%. •Switching group YNd11. •Standards IEC 60076, IEC60354 Genelec / SFS6001. •Primary Insulation Level UM123 LI550 AC230. •Primary bushings insulation UM123 LI550 AC230. •Secondary insulation level UM24 LI170 AC70. •Secondary bushings insulation UM24 LI170 AC70. Ambient conditions •Ambient air temperature range -40..+40°C. •The altitude above the sea level is well<1000m. •The design ambient temperature at which the permissible temperature rises over ambient temperatures are defined is 20ºC. Requirements •The transformer tank and other parts in contact with the outside air must be reliably protected against corrosion. •dBA level requirement (normal PM 60-65 dBA). •Radiators shall be hot-dip galvanised (SFS-EN ISO 1461). •Oil-immersed, Radiator Tank Design with Conservator Tank. •The oil supplied shall be in accordance with IEC 60296 class II. •The necessary de-conservation and oil treatment at site after the transport are included in the scope of supply of the transformer.•The transformer tank shall be vacuum resistant. •The transformer tank shall also be painted on the inside with a suitable paint.•Corrosion protection class minimum C3. •Winding CU. •Heat stabilized insulating paper shall be used as insulation for the windings. •Munksjö Thermo 90 transformer paper. •Tier 2 classification. Inspection and testing •Auxiliary voltages available 220 VDC and 400/230AC.Voltages according to IEC standard for below. •Insulation test voltage 50 Hz 1 min, voltage specified on each transformer below. •Control and signalling circuits test. •Surge voltage withstand. •Overvoltage test. •Short circuit tests according to 60076. Load capacity •Load capacity according to IEC. •Highest accepted temperatures at nominal load. •Winding temperature rise at warmest point 65K. •Oil temperature rise 60K. •At highest control point it is allowed 5K higher temperatures. Protection devices •Gas relay with separate alarm and trigger contacts. •Gas relay test pump. •Transformer tank relief valve(s) with trigger contact(s). •Oil thermometer with alarm and trip contacts. •Oil level indicator with alarm contact (for expansion tanks). •The Pt 100 sensor is for remote measurement of oil temperature, mA converter 4...20 mA should be included. •Winding temperature display with the necessary current transformers and with alarm and trip contacts. •The Pt 100 sensor is for remote measurement of the winding temperature and the transformer temperature, all winding temperature measurements shall be duplicated, mA converter 4...20 mA should be included. •Motor protection relay for the on-load tap changer. •Oil level indicator for on load tap changer. •Separate dehumidifiers for transformer and on load tap changer. Other •In line with section 97 of UtilAct, a tender submitted for the award of a supply contract may be rejected where the proportion of the products originating in third countries, as determined in accordance with Regulation (EU) No 952/2013 of the European Parliament and of the Council, exceeds 50 % of the total value of the products constituting the tender. This applies to products originating in third countries with which the EU has not concluded, whether multilaterally or bilaterally, an agreement ensuring comparable and effective access for Union undertakings to the markets of those third countries. •Delivery to the site (Rauhalahti power plant, Kammintie 2, 40520 Jyväskylä, Finland), including successful installation, testing and commissioning to be completed by 31.05.2026, and documentation provided thereof in Finnish. •The transformers will be part of a power distribution system for two 60 MW electric boilers.