SU1576911A1 - Dc transformer - Google Patents

Abstract

The invention relates to measuring and protective current transformers and can be used in systems for regulating, diagnosing and protecting high-power thyristor converters. The goal is to increase the load capacity and measurement accuracy. The DC transformer contains the first 1 and second 2 saturable transformers with a common primary winding, a maximum isolation circuit for diodes 3-6, a load 7, and a rectangular voltage source formed by a capacitor 9 and two anti-zener diodes 10 and 11. Using a rectangular voltage Power supply eliminates dips in the output voltage, which leads to an increase in load capacity and measurement accuracy. 2 Il.

Description

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The invention relates to measuring and protective current transformers and can be used in control systems, diagnostics and protection of powerful thyristor converters (rectifier-inverter substations for power transmission and DC-inserts, inverter systems for loading MGL channels, etc.).

The purpose of the invention is to increase the load capacity and accuracy of measurements of a DC transformer.

Fig. 1 is a diagram of a DC transformer; Fig. 2 is a diagram of the form of the supply voltage.

The direct current transformer contains the first 1 and second 2 saturated transformers, having a common primary winding with the measured current. The sequence with the secondary winding of the first saturable transformer 1 is connected to the first diode 3, and in series with the secondary winding of the second saturated transformer 2 is connected the second diode A. The cathode of the first diode 3 is connected to the cathode of the third diode 5, the fourth diode 6 is connected to the anode of the third diode 6 diode 5, and the anode to the anode of the second diode 4. Load 7 is connected by one output to the anodes of the first 3 and third 5 diodes, and the other output to the cathodes of the second 4 and fourth 6 diodes. A capacitor 9 is connected in series with the secondary winding of the supply transformer 8. Parallel to the capacitor 9 and the secondary winding of the transformer 8, a chain of two anti-switching zener diodes 10 and 11 is connected. One output of the chain of zener diodes Yu and 11 is connected between the secondary windings of saturable transformers 1 and 2, and another conclusion is between the anodes of the third 5 and fourth 6 diodes.

The DC transformer operates as follows.

The current 1c in the load 7 is formed by the diodes 5 and 6 of the current maxiselector at any time as the largest of the secondary currents ilf (), i.j.jCt) of saturable transformers 1 and 2

iw (t)), i, a (t) l

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Q 5 Q Q

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The secondary current of the saturating transformer 1 or 2 is a unipolar half-wavelength, formed when it is re-magnetized in an unsaturated region when it is operating in the current transformer mode.

An increase in the load capacity is achieved in a DC transformer using a periodic alternating alternating-voltage supply of a rectangular shape (Fig. 2). The simplest technical source of such a supply voltage is realized on a ballast capacitor 9 and two anti-switched Zener diodes Yu and 11 connected to the secondary winding of the supply transformer 8. The voltage on the secondary winding of the transformer 8 is sinusoidal with amplitude Um. The supply voltage of the DC transformer Un (t) is formed at the terminals of the chain of Zener diodes 10 and 11: a positive half-wave. forms Zener diode 10, negative Zener diode 11. Capacitance value of capacitor 9 is selected from the condition of current limiting in Zener diodes to the nominal value. Slope of half-wave front

at practically acceptable values of the capacitance of the capacitor 9 reaches

t

S4 — S5 — p; The supply voltage Un (t) is almost rectangular. The amplitude of the rectangular voltage pulses U0 is chosen to be equal to the amplitude Ulm of the secondary sinusoidal voltage of the transformer 8. Based on this condition, the zener diodes 10 and 11 are chosen. The maximum permissible load of the DC transformer is almost twice that of the known device. On the other hand, with the same load as in the known device, an increase in the load capacity is equivalent to a nearly twofold increase in the range of the measured current.

The advantages of the proposed device in comparison with the known one are in increasing the load capacity and measurement accuracy, which allows;

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ultimately, expanding the capabilities of secondary protection devices, diagnosing and regulating high-power thyristor converters.

Claims (1)

Invention Formula A transformer of direct current containing the first and second saturated transformers with a common primary winding, the first diode connected in series with the secondary winding of the first saturable transformer, the second diode connected in series with the secondary winding of the second saturated transformer, the third diode connected by a cathode to the cathode of the first diode, the fourth diode connected by the cathode to the anode of the third diode, and the anode to at Rig. g sixteen OHOIV of the second diode, the load connected by one output to the cathodes of the first and third diodes, another output to the anodes of the second and fourth diodes, a power transformer, characterized in that, in order to increase the load capacity and accuracy of measurements, a capacitor and a chain of two opposite zener diodes, one output of a chain of zener diodes connected between the secondary windings of saturable transformers and through the capacitor is connected to the first output of the secondary winding of the supply transformer, the second output of the chain of zener diodes is connected to the anode of the third and the cathode of the fourth diode and with the second output of the secondary winding of the supply transformer. T / 2 T