Toroidal Core Electronic Transformer With Winding Data and secondary transmission and for secondary distribution, (above 250 kVA) are foundation mounted outdoor type. The several compartments in which the indoor substation is divided are control compartment, indicating and metering instruments and protective device compartment, circuit breaker and operating mechanism compartment, main bus-bar compartment and current transformer and cable sealing box compartment. Other important specifications to consider when searching for High voltage transformers include maximum secondary voltage rating, maximum secondary current rating, maximum power rating, and output type.
Since the secondary coil has 10 times fewer windings, it creates a current with 10 times lower voltage. The service for voltage transformers provides measurements of ratio correction factors and phase angles at primary voltages up to 170 kV and secondary voltages as low as 10 V at 60 Hz. Calibrations at frequencies from 50-400 Hz are available over a more limited voltage range. The CVT is designed to supply an overload of 150% at around 200% overload the output waveform collpases to near 0V, WITH NO HARM TO THE CVT , direct short circuiting for long periods of time is not a problem for the CVT , as soon as the short is removed it will carry on supplying useable power.
A load is connected across the secondary winding, the secondary current produces a secondary flux which tends to cancel the primary flux. A conventional transformer has a ratio of turns between the primary and secondary windings, which are magnetically coupled on a common core. They are designed to present negligible load to the supply being measured and have an accurate voltage ratio and phase relationship to enable accurate secondary connected metering.
This causes metering CTs to saturate at lower secondary voltages saving sensitive connected metering devices from damaging large fault currents in the event of a primary electrical fault. This affords easy implementation on high voltage bushings of grid transformers and other devices by installing the secondary turn core inside high-voltage bushing insulators and using the pass-through conductor as a single turn primary. They are designed to present negligible load to the supply being measured and have an accurate current ratio and phase relationship to enable accurate secondary connected metering.
Instrument transformers may also be used as an isolation transformer so that secondary quantities may be used in phase shifting without affecting other primary connected devices. Primary winding of connected in secondary winding is connected in open delta.sometimes additional secondary winding is provideded in R.V.T. for measuring purpose and is connected in Star.Ratio of generally specified as line-to-line primary voltage to open delta residual ,therefore,becomes necessary to mention system neutral condition so as to select phase voltage of the open-delta winding are used along with capacitor Bank ,capacitor bank gets discharged through primary winding ‘AE' makes suitable for such applications also. ^ This also implies the following: The net core flux is zero, the input impedance is infinite when secondary is open and zero when secondary is shorted; there is zero phase-shift through an ideal transformer; input and output power and reactive volt-ampere are each conserved; these three statements apply for any frequency above zero and periodic waveforms are conserved.