SU920864A1 - Ac transformer - Google Patents

Description

(54) AC TRANSFORMER

one

This invention relates to the measurement of elec. tric currents.

Known transformer AC, made on the ferromagnetic core with the primary and secondary windings 1.

A disadvantage of this device is the low output power at low primary currents.

The closest to the proposed technical essence and the achieved result is an AC transformer, made on a ferromagnetic core with a primary winding connected to the circuit of the measured current, and a secondary winding connected in series with the load, containing a source of bias voltage 2.

However, this transformer is characterized by insufficient linearity of the characteristic and large angular error.

The purpose of the invention is to improve the linearity of the characteristic and reduce the angular error.

This goal is achieved by the fact that the transformer is supplied with non-linear resistance

and a capacitor connected in series with the secondary winding of the transformer, a load and a source of bias voltage, the core of the transformer is made with a gap, and the source of the bias voltage is stabilized.

The drawing shows a diagram of a transformer.

The transformer 1 has a primary 2 and a secondary 3 windings deposited on the core 4, made with a gap. In chain

10 winding 3 of the transformer includes a load resistance 5, a capacitor 6 and a nonlinear resistance 7 (two zener-diode connected in opposite-series). The bias voltage is applied to

5 a secondary winding circuit3 through a stabilizer made on a resistor 8 and a nonlinear resistance 9, and a matching transformer 10.

Claims (2)

The capacitor 6 compensates the inductive component of the circuit at a frequency of 50 Hz, which reduces losses and ensures the independence of the device from the shape of the primary current curve, and the nonlinear resistance 11 limits the voltage of the winding 3 when the primary current reaches the specified value. The air gap of the magnetic circuit 4 ensures the linearity of the characteristics and the independence of the angular error of the transformer from the primary current. In the presence of current in the primary winding 2, two voltages act in the circuit of the winding 3: the EMF of the secondary winding 3 and the magnetically stabilized bias voltage, the value of which is chosen close to the primary voltage of the resistance 7. The resulting voltage is determined by the EMF value relative to the voltage The bias bias and taking into account the magnitude of the linear impedance of the load 5 and the nonlinear impedance 7 determines the load current, which is the sum of the actual secondary current and the bias current. Moreover, at a certain phase angle and low primary currents, the load current may exceed the value of the primary current brought to winding 3. The current transformer has a simple design, increased secondary current and power with a strongly pronounced dependence on the phase of the primary current, high linearity of the characteristic and a weak dependence the angular magnitude of the error of magnitude and distortion of the shape of the primary current curve. Claims. An alternating current transformer made on a ferromagnetic core with a primary winding connected to the measured current circuit and a secondary winding connected in series with the load containing a bias voltage source, characterized in that, in order to improve the linearity of the characteristic and reduce the angular error, it supplied with nonlinear resistance and capacitor, connected in series with the secondary winding of the transformer, load and bias voltage source, transformer core the torus is made with a gap, and the source of bias voltage is stabilized. Sources of information taken into account in the examination 1. AM Fedoseev, M. Osnrvy relay protection, M.-L., GEI, 1961, p. 64, fig. 2-32. 2. USSR author's certificate number 74018, cl. P 01 F 40/06 1947. //