COF oil-insulated current transformersfor outdoor installations are based on a top core design. All our current transformers are built-to-order to customer specifications. COF current transformers can meet many applications for metering and protection with a number of dome sizes for up to three independent cores from 25 kV up to 170 kV. This current transformer is available with either porcelain or silicone rubber insulators, with ANSI 70 gray porcelain insulator considered as the standard product. Hermetic sealing of the design is accomplished using a gas cushion above the oil to prevent free-breathing outside moisture-laden air.
The COF demonstrates reliable performance in service with a low field failure rate that is lower than the industry average. This design has been installed all over the western hemisphere from desert to arctic climates.