| 摘要 |
A switchgear device (10) comprises a housing containing a circuit breaker (50) and a capacitor voltage transformer (CVT). The CVT consists of a stack of serially-connected capacitors (30) connected between a first terminal (90) and a ground potential, and a digital electronic isolator (20) connected in parallel between the lower capacitor (40) of the stack (30) and ground. The output of the isolator (20) is connected to a complementary circuit (120) distant from the isolator via a fibre-optic cable (110). The digital electronic isolator (20) is substantially smaller than either an electromagnetic or a power-amplified analogue device, and it has a high input impedance, thereby buffering the capacitor stack (30) which may therefore be reduced in size. The overall reduction in size of the components of the CVT permits them to be fitted into the body of a standard circuit breaker with consequent cost savings.
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