Wind turbines typically produce power at around 690 volts, which is transformed to distribution network voltage (usually 11 kV to 33 kV). The transformers are most often placed in their own cubicle, adjacent to the base of the tower. Apart from being unsightly, this necessitates the construction of a weatherproof housing, putting up cost. Although "dry" transformers can be used, many are oil-cooled. German wind turbine supplier Enercon is now switching to the use of hermetically sealed transformers with a silicone fluid as coolant, developed in conjunction with its transformer supplier, Pauwels, which are sufficiently compact to fit into the base of the tower and have high efficiency at low load -- an important consideration in the case of wind turbines. So far, 1000 of the units have been delivered with no public reports of breakdowns.