Patent ID: 7928722

Claim:
A voltage sensing system, comprising: a housing having a first voltage isolation circuit coupled to a controller and an interface, the first voltage isolation circuit including: a current limiting resistor coupled to an input; voltage, a current transformer having a primary winding and a secondary winding, wherein the magnitude of current flowing through the primary winding is established by the current limiting resistor, and an inverting operational amplifier (“op-amp”) connected to the secondary winding, wherein an inverting input of the op-amp is coupled to an output of the op-amp via a gain resistor, and wherein an output voltage at the output of the op-amp is established by the gain resistor, and wherein the ratio of the input voltage to the output voltage is proportional to the ratio between the value of the current limiting resistor and the value of the gain resistor, wherein the controller is programmed to produce a value indicative of the output voltage and to provide the value via the interface to an external system.