An exceptional technical challenge was presented by the mobile transformer that the Chilean energy concern EMEL commissioned Rhona, the largest producer of transformers in Chile, to produce. The conditions: the 30MVA transformer needed to be henceforth freely utilized and provide controlled voltage for the undervoltage-side in both 66 kV and 100 kV network.
To be able to switch from 110 kV to 66 kV with the press of a button, a sophisticated solution was necessary as a series-parallel connection did not suffice. For this reason a special combination of two DEETAP® DU off-circuit tap-changers for single-bridging connection and a DEETAP® DU for series-parallel connection was employed. Additionally the control of the undervoltage-side could not be applied in the standard way because, due to the low voltage, the current for direct control would have been too large. Therefore it was necessary to use a booster transformer so that an on-load tap-changer VACUTAP® VV could regulate the undervoltage in the so-called intermediate circuit.
Area Sales Manager Heinz Sperger and off-circuit tap-changer specialist Amthor drew up an offer within one day. This offer already contained the draft connection diagrams for the off-circuit tap-changer. The specialists helped Rhona on site with the installation of the complex off-circuit tap-changer free of charge.
| Technical Data |
|---|
| High-voltage side: | 100 kV or 66 kV (regulation on one tap with 2 X DEETAP® DU III 200-123-12 02 0S) |
| Undervoltage: | 24kV or 14.4 kV +/- 10 % (regulation by VACUTAP® VV III 250 D 76 12233W in the intermediate circuit). |
| High-voltage current: | 151 A |
| Undervoltage current: | 226 A (in the booster) |
| Tap voltage high-voltage: | 44 kV |
| Tap voltage undervoltage: | 819 V |
RHONA came into existence with the combination of the two engineering offices Neuweiler & Reitz and Aspillaga Ltda &Cia Ltda Hornauer. Their cooperation dates back to 1943. They merged in 1964 to become the biggest producer of transformers in Chile.
The EMEL Group consists of six electricity distribution subsidiaries and other concerns which provide services. EMEL is controlled by CGE (Compañía General de Electricidad), which has a 97.94% holding. With more than 2.1 million customers, the EMEL group is the number one electricity supplier in Chile.