Use 1.5~3V dry battery to connect the positive pole to the primary coil L1 of the transformer. L2 is connected to the negative pole. The secondary side K1 of the transformer is connected to the positive electrode of the milliampere meter, and the negative pole is connected to K2. After the wire is connected, the K is closed. The pointer is positively biased. After the pull-off, the pointer of the milliampere meter is negatively biased, indicating that the end of the transformer connected to the positive pole of the battery is of the same polarity as the end connected to the positive end of the milliampere meter.
1. K1 is the same polarity, that is, the transformer is depolarized. If the pointer swings opposite to the above, the polarity is added.
The amount of compensation is as follows:
Number of compensation
Only the contrast difference acts as a compensation, and the compensation amount is independent of the secondary load and current magnitude. The number of compensation parameters is generally only a few, and the compensation for the number of turns should be calculated when the secondary impedance of the current low terminal is maximum, and the error of the secondary impedance of the current high terminal is the smallest. For high-precision miniature current transformers, if the compensation is only 1 匝, it will compensate for the excess. At this time, half-turn or fractional 匝 compensation can be used. However, the number of turns of the current transformer is calculated by the closed loop through the core window, and the number of turns of the current transformer is calculated one by one, and there is no such case. For the use of semi-turn or fractional enthalpy compensation, auxiliary means such as: double winding, double iron core, etc. must be used. Auxiliary core compensation contrast is poor,
The angular difference plays a compensating role, but the method of making the auxiliary core compensation is more complicated. For capacitor compensation, the capacitor can be connected directly across the secondary winding. The contrast difference is positive compensation, the compensation size is proportional to the X component of the secondary load Z=RiX, and proportional to the compensation capacitor size; the diagonal difference is negatively compensated, the compensation magnitude and the secondary load Z=RiX The component is proportional to the compensation capacitor size. Capacitance compensation is an ideal compensation method. In the miniature precision current transformer, the current/voltage conversion of the secondary winding directly connected to the operational amplifier has a secondary impedance of substantially zero, and the effect of the capacitance compensation is relatively small. Generally, the phase shift circuit can be added in the current/voltage conversion stage to solve the angular difference problem. The user can adjust and calculate the phase shifting circuit according to the test error data in the test report of the transformer of the current transformer when it is shipped from the factory.