简答题The secondary winding of ct can be open for a short time, but not for a long time. A、正确 B、错误简答题Capacitive voltage transformers are widely used in 100~500kV neutral ground system. A、正确 B、错误简答题The current transformer should be connected according to the polarity reduction, L1 is the primary current inflow end, then K1 is the secondary current inflow end. A、正确 B、错误简答题The single-phase current transformer with the secondary rated current 5A has a rated capacity of 25VA and a rated impedance of 1 Ω. A、正确 B、错误简答题The operating status of the current transformer is characterized by () A、The primary winding is connected in series in the primary circuit B、 Under normal circumstances, the ct is close to short-circuit operation C、 The primary current has nothing to do with the change of the secondary load D、Open circuit of secondary winding is not allowed during operation简答题Is it necessary to install fuses on the primary side of 110kV and above voltage transformers? Is the following statement correct? () A、110kV and above system is neutral point directly grounded system, each phase of the voltage transformer can withstand the line voltage operation for a long time, so there is no fuse installed in the primary side B、110kV and above system is neutral point directly grounded system, each phase of voltage transformer cannot bear line voltage operation for a long time, so fuse is not installed in the primary side C、 The structure of 110kV and above voltage transformers adopts single-phase cascade type, with high insulation strength, so no fuse is installed in the primary side D、Fuses shall be installed on the primary side of 110kV and above voltage transformers简答题Three-phase voltage transformers are mainly used in voltage grades above 110kV. A、正确 B、错误简答题In low voltage distribution units, the voltage transformer can be directly connected to the power grid through the fuse without isolating switch. A、正确 B、错误简答题When a short circuit occurs in the primary circuit, the error of the CT will be ( ). A、Decreased B、 Increase C、 The same D、Not sure简答题The transformer ratio of capacitive voltage transformer is sensitive to the change of power network frequency, and its accuracy is relatively low. A、正确 B、错误简答题The standard accuracy levels of current transformers are (). A、0.2 B、0.3 C、1 D、3简答题When a current transformer works at level 0.5, the rated load on the secondary side is 0.4Ω . When the actual load on the secondary side is 1.2 Ω, the error ( ) A、Decreased B、Increase C、 The same D、 Not sure简答题The rated voltage of the ct is the voltage applied to both ends of the primary winding. A、正确 B、错误简答题220 kv voltage transformer isolation switch operation, should pull open the second fuse, this is to ( ). A、Prevent fuses from fusing B、Prevent backcharging C、Prevent secondary grounding D、 To prevent short circuit简答题The difference between a voltage transformer and a power transformer is ( ). A、Voltage transformer has iron core, transformer has no iron core B、 The voltage transformer has no iron core, and the transformer has iron core. C、The voltage transformer is mainly used for measuring and protecting, and the transformer is used to connect the power grid with two voltage levels D、The rated voltage of the transformer is higher than that of the voltage transformer简答题The standard accuracy grades of current transformers for protection are () A、1 B、3 C、5P D、10P简答题The rated voltage of jCC1-110 single-phase cascade voltage transformer is 110KV. A、正确 B、错误简答题On the low-voltage side of the voltage transformer, the voltage of one phase is zero and the voltage of two phases remains unchanged, while the line voltage of two decreases and one remains unchanged, indicating ( ). A、Low voltage side two phase fuse break B、 One phase fuse is broken on the low pressure side C、High pressure side one phase fuse broken D、 Two phase fuse is broken on the high pressure side简答题The primary side of the voltage transformer should be grounded reliably to prevent high voltage from jumping into the secondary side. A、正确 B、错误简答题The rated capacity of the voltage transformer refers to its maximum capacity. A、正确 B、错误