When it comes to micro transformers, the current transformer can not be used as a voltage transformer, because the essential difference between the current transformer and the voltage transformer is that the current transformer winding turns are relatively small, often only one turn, when two times on the rated load, from a time to see, the impedance is very small, and as a voltage measurement, is connected to both ends of the circuit under test and requires a large input impedance.
This micro-transformer is actually the first obstacle to the use of the current transformer as a voltage transformer. Next, we should also pay attention to the micro transformer in the current transformer can not be used as a voltage transformer, because the current transformer operation in the rated load, the primary winding pressure drop is very small, meaning that parallel at both ends of the measured circuit when the voltage transformer is used, only a very weak voltage can be measured.
This is the second obstacle to the use of current transformers as voltage transformers. The principle of current transformer in micro-transformer will also be based on the principle of electromagnetic induction. The current transformer itself will consist of a closed core and winding.
It has a small number of side winding turns, strung in the line that needs to be measured, and that's why it often has all the current of the line flowing through, with more than two side winding turns, strung together in measuring instruments and protection loops. When the current micro-transformer is working, its two side loops are always closed, so the impedance of the measuring instrument and the Protection Loop series coil is very small, and the working state of the current miniature transformer is close to short circuit.
The current transformer is to measure the first side of the large current into two side small current, two times can not open the road. As mentioned above, the current transformer in the micro transformer can not be used as a voltage transformer also 90 for the above reasons.
In fact, at the end of the day, about micro-transformers in the use of current transformers and voltage transformers, we should pay attention to the use of specific conditions, to ensure the use of the effect.