The conductor on which the transformer is mounted will act as primary windings of the current transformers. The vacuum circuit breaker manufacturer of the current transformers carry the current which is to be measured, and it is connected to the main circuit.
Setzermann current transformers Smart are suitable for mounting on printed-circuit boards in the electric range of modern drive engineering for control purposes and measurement value logging. They include an earthed screen to shield the secondary winding from the electric field of the conductor, thereby allowing the secondary insulation level to be a nominal 2 kV. This assembly is held at earth potential by connecting the CT core-shield assembly to an independent earth cable at one point only, to prevent any circulating current paths. Current transformers for measurement and protection purposes are required throughout a power station auxiliary system.
Current transformers (CTs) are used to reduce the current levels from thousands of amperes down to a standard output of either 5 A or 1 A for normal operation. The ideal current transformer may be defined as one in which any primary condition is reproduced in the secondary circuit in the exact ratio and phase relationship. The secondary of a current transformer should not be disconnected from its rated burden while current is flowing in the primary.
The primary winding of the transformer is connected in series with the load and carries the actual current flowing to the load, while the secondary winding is connected to a measuring device or a relay. Current transformers supply the protective relays with currents of magnitude proportional to those of power circuit but sufficiently reduced in magnitude. A current transformer is an instrument transformer, used along with measuring or protective devices, in which the secondary current is proportional to the primary current (under normal conditions of operation) and differs from it by an angle that is approximately zero.
In order to short circuit current transformers and for the purpose of recurrent comparative measurements it is recommended that special terminal block for DIN rails be used.These comprise a cross-disconnect terminal with measuring and test equipment, insulated bridges for grounding and short circuiting of the current transformer terminals. It is therefore the case that open operation of CTs must be avoided and unloaded current transformers must be short circuited. Eaton’s 5A split core current transformer is engineered for electronic metering applications specifically designed to install around primary conductors without disconnecting wires or breaking the circuit to be monitored.
Flex-Core manufactures and warehouses a large selection of Current Transformers , Transducers , Meters and more for measurement, monitoring, and control of current, power, and energy applications. AC/DC sensitive measuring current transformers use a special measurement method to detect both AC and DC currents of different frequencies. The output signal of the transformer is an accurate voltage waveform representation of the measured current, which may be analyzed on an oscilloscope, RF power meter, spectrum analyzer or custom interface circuitry.
Current transformers are used for protection, measurement and control in high-voltage electrical substations and the electrical grid Current transformers may be installed inside switchgear or in apparatus bushings, but very often free-standing outdoor current transformers are used.