SU877651A1 - Mining voltage relay - Google Patents

Description

The invention relates to protection and automation devices, in particular, to devices for supplyless power supply to responsible consumers of alternating current, which do not allow a long power interruption. Voltage relays are used that are used in devices for protecting networks against power supply voltage loss or for reducing the latter below a set value, for example, a voltage control device containing rectifier and rectified voltage to pulse voltage converter, in which the alternating voltage is first rectified, and then converted into a pulse, the duty cycle of which is proportional to the amplitude of the input signal X. The disadvantage of this device is the low speed due to the inertia of the process conversion of alternating voltage to constant and subsequent conversion of constant to pulsed. . The closest in technical essence to the present invention is a voltage relay containing a transformer, a full-wave rectifier, a capacitive filter, in which the controlled voltage from the output winding of the transformer goes to one of the comparator inputs through a series connected rectifier and capacitive filter, and the second input of the comparator receives a constant reference voltage L J The disadvantage of this relay is the slow response due to the inertia of the capacitive filter. The purpose of the invention is to increase speed. The goal is achieved by the fact that a minimum voltage alternating current relay containing an input transformer, to the secondary winding of which is connected one of the inputs of a comparator loaded on an actuator, is equipped with series-connected synchronized generator of rectangular bipolar pulses of double frequency relative to the input voltage relay, integrator and voltage limiter connected between the output winding of the transformer and the second input of the comparator.

The synchronized square-wave bipolar pulse generator I contains at its input a zero-body, the output of which is connected to one of the inputs of the coincidence polarity of the pulses directly, and to its second input through the series-connected integrator and the second null-organ. Thus, the device eliminates an additional error due to a change in the frequency of the input voltage.

FIG. 1 shows a relay diagram.

The device comprises an input transformer 1, to the secondary winding of which a synchronized generator of 2 double-frequency square-wave pulses, an integrator 3, a voltage suppressor 4 and a comparator 5 loaded on the actuator are connected; in fig. 2 is a timing diagram of the voltages acting on the outputs of the functional units of the relay / FIG. 3 is a diagram of a synchronized generator of rectangular pulses of double frequency.

The synchronized generator contains a zero-body b and 7, an integrator. 8, the coincidence circuit of the polarities of the output pulses of the zero organs b and 7,

FIG. 4 is a timing diagram explaining the principle of operation of generator 2.

The principle of operation of this relay is to compare the input sinusoidal voltage with the common-mode trapezoidal impulse voltage used as the reference voltage.

At the output of generator 2 (Fig. 1), after each transition of the input sinusoidal voltage (Ugj) through a non-zero value, a positive square wave with a quarter-period / oscillation duration is formed (voltage U of Fig. 2). This voltage i is fed to the integrator 3, at the output of which triangular-shaped pulses appear (voltage 1) 2). The transformation of the triangular pulse into trapezoidal shape is carried out using a voltage limiter 4, where the amplitude of the input voltage is limited at the level. The output signal of the relay appears when the output voltage drops below the reference, this voltage comparison is performed by the element 5. The maximum error of the approximation of the sinusoidal voltage of the trapezoidal can be

(when -) order 14.

Heme ator 2 (fig. 1) is most rationally executed according to the scheme shown in fig. 3. Here, at the output of the ul-organ 6, rectangular pulses appear, the duration of which is equal to the half-period of the input voltage oscillations. At the output of the integrator 8, triangular-shaped pulses (Fig. 4) are generated, arriving at the input of another zero-organ 7. The rectangular pulses at the zero-organ output 7, similar to the zero-organ b output pulses, have a duration equal to half a period, but are shifted relative to the moments of transition of the input voltage through a zero value by a quarter period. The output signals of the zero-organs 6 and 7 are fed to the input of the logic circuit of the coincidence of the polarities of the pulses, at the output of which rectangular pulses of twice the frequency appear.

The response time of the proposed relay does not depend on the phase of input voltage lowering below the set value and is practically zero, which is very important when using the relay in high-speed uninterruptible power plants, since in this case it reaches 5 with a significant increase in the reliability of power supply most responsive; .

Claims (2)

1. Undervoltage Relay Containing an Input Transformer to the Secondary Winding which one of the inputs is connected comparator loaded on the executive body, characterized in that, in order to increase speed, it is equipped with series-connected synchronized generator of rectangular bipolar pulses of double frequency with respect to the input voltage frequency of the relay, integrator and voltage limiter connected between transformer windings of the transformer and the second input of the comparator. 2. The relay according to claim 1, characterized in that the synchronized generator of rectangular bipolar pulses contains a nullorgan at the input, the output of which is connected to one of the inputs of the polarity matching circuit of the pulses directly. but, and to its second input through a series-connected integrator. and the second null organ. Sources of information taken into account in the examination 1. US patent number 3852731, cl. 340-248 B, 1974. 2. Greyvulis Ya.P. et al. Semi-current and voltage relays. . , Energie, 1970, p. 12-41 (protype).