Switchyard's Voltage Measurements for Smart Grids

http://lmgtfy.com/?q=HV+Sensor+measuring+transformers+from+220kV+up

You can use a "bushing potential device" BUSHING POTENTIAL DEVICE which taps into the capacitance tap at the base of a bushing and is use for measuring voltage in transmission lines and substations. It is not as accurate as an actual potential transformer which is a separate device in a switchyard that measures voltage and is quite expensive and must be designed into the substation structure. Various portable equipment is available if the measurement is temporary but need a lot of training and extra equipment to use. I have been around when power company personnel used it from their bucket truck, but didn't like the idea. The other way is to use the Low voltage side of the transformer to measure voltage. Even if it is 15KV, that is still a lot easier than 220KV. A Question, is this a utility owned substation, a user owned substation, or half and half. The voltage where the power is purchased will have metering on it. That metering will have a voltage input. The easiest way is to get utility permission to monitor the voltage for the metering. You will have to demonstrate that you will not be loading that potential source and altering the metering.