Tham khảo tài liệu 'bishop, robert h. - the mechatronics handbook [crc press 2002] part 18', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | This form of divider is useful from low frequencies up through frequencies of several megahertz. A common application is in the scaling of large voltages. Inductive Dividers If the elements in the chain divider are inductors then an autotransformer results. Inductive dividers are useful over frequencies from a few hertz to several hundred kilohertz. Errors in the parts-per-billion range are achievable. Voltage Transformers Voltage transformers constitute one of the most common means of accomplishing voltage scaling at line frequencies. Standard double-wound configurations are useful unless voltages above about 200 kV are to be monitored. For very high voltages alternative configurations such as the capacitor voltage transformer and the cascade voltage transformer are employed Gregory 1973 . Current Scaling Current scaling is typically accomplished via either a current shunt or a current transformer. A current shunt is essentially an accurately known resistance through which the current to be measured is passed. The voltage developed across the shunt as a result of the current is the quantity measured. Shunts are useful at DC and frequencies through the audio range. Two disadvantages are 1 the shunt consumes power and 2 the measurement circuitry must be operated at the same potential as the shunt. The current transformer overcomes the mentioned disadvantages of the current shunt. Typically the current transformer consists of a specially constructed toroidal core upon which the secondary sense winding is wrapped and through which the primary winding is passed. A single-turn primary is commonly used although mutiturn primaries are available. Other Attenuators In addition to the aforementioned means of voltage and current scaling are attenuator pads which provide in addition to voltage or power reduction the ability to be matched in impedance to the source and load circuits between which it is connected. The common pads include the T L and n types either balanced or .
