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Active Energy Transducer
This transducer is used for measurement of Active Energy for single phase (STE-A-14T) system as well as for 3-phase, 3-wire (STE-B-14T) system and 3-phase 4-wire (STE-C-14T) systems
with balanced and unbalanced load. This is fully solid-state instrument, which can be interfaced directly with Digital Data Acquisition System. The Input Currents are galvanically
isolated and suitally scaled down by transformer T1, T2 etc. The Voltage are scaled down by high impedance resistor networks. Depending on the system one or more electronic
multipliers M1, M2 etc are used. The multiplying circuit used is the popular time division multiplication method. The implementation of the TDM technique as designed by SITU makes
the accuracy of multiplication dependent only on a few precision resistors and a low temperature coefficient reference zener.
The outputs of the multipliers are summed up and fed to a precision voltage to frequency converter F. The frequency converter converts the input voltage to a proportional frequency
by using "State-of-the-art" charge feedback technique. The output of the frequency converters in the form of pulses, which is then divided by using digital technique, the division
factor depending on the input transformation ratios. The divided pulse rate is then output as a potential free contact.
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