Tyree Transformers has recently delivered two 6/8MVA ONAF Power Transformers to a regional power utility business, EA Networks who operate a network in the south island of New Zealand.
The two units were transported fully assembled from Tyree’s Mittagong operations to Lyttleton Port near Christchurch and successfully transported to the EA Networks substation sites at Tinwald and Fairton.
The 3-winding transformers were rated 22/11kV with a 6.6kV tertiary stabiliser winding and connected with a YNyn0+d1 vector to provide a network interconnection for critical, seasonal loading changes within the network.
The units were designed with a 10MVA 120hour overload rating, and the necessary electro-mechanical strength to provide through fault withstand capability over the transformers design life as necessary for an interconnecting transformer. The Tyree design successfully pass full type testing to this duty cycle as part of the stringent FAT testing programme required by EA Networks.
The units incorporated SEL 2414 Transformer Management Relays and were also specifically designed to meet New Zealand seismic conditions and corrosion protection requirements.
Tyree exclusively use thermally upgraded cellulose insulation papers on our power transformer windings. Tyree employ a pressing and stabilising process of power transformer windings that is proven for manufacture of transformers capable of short circuit withstand. The active part assembly was dried using Tyree’s proprietary vacuum drying process that limits oxidisation. At tanking, after dry out we successfully achieved a final test result on direct insulation paper samples of 1190 DP. (The Degree of Polymerisation DP testing was completed by independent laboratory using an average viscometric degree of polymerisation to ASTM D 4243-99).
This excellent DP result revalidates and is a clear example of the Tyree vacuum dry out process achieving the reduced levels of insulation paper aging during production which is expected of modern power transformer manufacturers.
For inquiries on power transformers and other Tyree products please contact our sales team by email on firstname.lastname@example.org or +61 2 48726177