SU1089693A1 - Device for protecting three-phase load against phase alternation change and open phase - Google Patents

Abstract

A DEVICE FOR PROTECTING THREE-PHASE LOAD FROM A CHANGE OF ALTERNATING PHASES AND CRUSHING PHASES, containing, by the number of phases, three converters of sinusoidal network voltage signals into rectangular pulses associated with elements AND and NOT, and an actuator, characterized in that increase the reliability, the output of the first converter of the sinusoidal signal of the mains voltage to the rectangular pulses is connected to the second input of the second And element and the input of the first ajieiieHTa NOT, the output of which is connected to the first input of the first AND element the output of which is connected to the first input of the first AND element, the output of which is connected to the input of the third element NOT, whose input is connected to the second input of the first AND-NOT element, the output of the second converter is connected to the second input of the first element AND and the input of the second element NOT, output which is connected to the first input of the second element AND-NOT, the output of which is connected to the first input of the second element AND, the output of which is connected to the input of the fourth element NOT, the output of which is connected to the second input of the second element AND-NOT, With the output The third converter connects the dinne with the first inputs of the third and fourth element And, the second inputs of which are connected respectively to the outputs of the first and second elements NOT, the third inputs of the third and fourth elements NOT, the third inputs of the third and fourth elements And O 00 are connected respectively to the outputs of the second and first voltage transducers, the fourth inputs of the third x and the fourth And elements are connected respectively to the outputs of the first with OO and the second And elements,

Description

The invention relates to electrical engineering and can be used in on-board emergency control automation to protect three-phase loads from incorrect phase alternation of phase failure 5 as well as to turn on three-phase loads, in particular, in automated systems.

A device is known for monitoring the phases of a network consisting of a threshold and an actuator, three LEDs, two threshold blocks, two time blocks, a delay, a frequency selection block and a logic signal processing unit whose output is connected to the input of the actuator, and the inputs are to the outputs the LEDs, the LED inputs of the two large phases are connected to the output of the time delay blocks, and the inputs of the latter are connected to the outputs of the respective threshold blocks, the input of the third LED is connected to the output of the block tnoj selection input of which is connected to the output sootvetstvugaschego threshold element l, known apparatus rather slab but since special blocks has a fixed delay., hydrochloric block selection frequency, the signal processing logic block and svetodiodoz that significantly reduces rshdezhkost and performance of the device. In addition, this device cannot operate in the rshrokom frequency range, which is limited by blocks of time delays, and frequency selection :: at frequencies lower than constructively caused5 it generally does not work, but at frequencies; False actuation occurs in a structural manner. The closest in technical essence to the present invention is a device for protecting three-phase and three-phase loads from changes in phase alternations and detecting phase failure, consisting of current-voltage converters, operational amplifiers connected in accordance with the a comparator, an executive body of four two-input elements AND, three combined triggers, a three input elements AND, a delay element, a constant source and a controlled single HNmy generator jTbcoB, and the outputs of the operative amplifiers of the amplifiers are connected to one of the inputs of two-input elements And, the other input of which is combined and connected to a controlled generator of single I1 pulses, and the outputs of the above-mentioned two-input elements And are connected to the counting T-inputs of the corresponding triggers, control inputs S and R are respectively combined

connected to a controlled generator of single pulses, J-input of one trigger connected to a constant signal source, J-input of another trigger connected to a direct

the output of the first trigger, and J the input of the third trigger through the two-way element I is connected to the direct outputs of the first and second triggers, while the K inputs of the first two triggers are connected to the inverse output of the third trigger, the K input of which. connected to its own inverse output through the delay element, and all the direct outputs of the flip-flops are connected to the inputs of the three-input element I, the output of which is connected to the executor. The known device is intended to achieve a three-phase load from nonpHBtmbHoro phase rotation, phase failure, as well as to include a three-phase load, in particular, in automated gyroscopic instruments control systems 2. However, the known device is complex in design and interrelation between the elements Single-pulse generator and device delay element must be adjusted according to the frequency of the supply voltage. The device triggers an output pulse only with one phase rotation, and the absence of a signal can be interpreted as a fault of the device itself. The purpose of the invention is to simplify the device, increase the reliability of its operation. The goal is achieved by the fact that in the device, to protect the three-phase load from changing phase alternation and phase failure, containing three transducers of sinusoidal voltage signals by the number of phases into rectangular pulses entered with elements AND and NOT, and an executive element, the output of the first voltage-to-square sine wave converter is connected to the BTQ input of the second AND element and the first NO element, the output of which is connected to ervomu input of the first AND-NO element whose output is connected to a first input of a first AND gate whose output is connected to an input element of the third NOR You are a. the stroke of which is connected to the second input of the first NAND element, the output of the second converter is connected to the second input of the first element AND and the input of the second element NOT, the output of which is connected to the first input of the second AND element, the output of which is connected to the first input of the second element AND, the output of which is connected to the input of an open element NOT, the output of which is connected to the second input of the second element NAND, the output of the third converter is connected to the first inputs of the third and fourth elements AND, the second inputs of which are connected respectively to The outputs of the first and second elements are NOT, .. the third inputs of the third and fourth elements AND: connected respectively to the outputs of the second and first voltage converters, the fourth inputs of the third and fourth elements AND are connected respectively to the outputs of the first and second elements I. In FIG. Figure 1 shows the block diagram of the device; Fig. 2 shows timing diagrams of the operation of the elements of the device with a direct sequence of alternating phases; on fig.Z - the same, with the reverse sequence. The device contains three converters 1 - 3 sinusoidal signals of the mains voltage into a series of rectangular impulses HE 4–7, AND – HE 8 elements and AND 10–13 elements connected by their inputs to the three phases of the mains supply. The device works as follows. The INPUTS of the signal converters 1, 2 and 3 receive the voltages of phases A, B and C, respectively, from the outputs of which a series of pulses with a duration of 1/2 T and a repetition period T are taken. The series of pulses U | they go to the second input of the second element 11 and to the input of the element 4, from the output of which signals are fed to the first input of the first element AND-H 8, from the output of which signals are fed to the first input of the first element 11, from which they go to the input of the third element is NOT 6. A series of single pulses Ug is formed at the time of the presence of the signal U and the signal U. A single pulse on the element I 10 is preserved even when there is a signal 1b, and no signal and due to feedback from output 6 to the second input of the element NOT that AND-NOT 8. A series of pulses 11 n It comes to the second input of the first element AND 10 and to the input of the second element NOT 5, from the output of which signals are fed to the first input of the second element 9, from the output of which pulses are fed to the first input, the second element And 1 1, the signals from which are fed to the input of the fourth He element 7. A series of single pulses Uj-j is formed sa by the presence of signals and and U2; the signal on the element II is also preserved in, the moment of the signal U's harsh and the absence of the signal U due to feedback from the output of the HE 7 element to the second input of the AND-NE element 9. The control signals U and U about changing the alternation or loss of phases arrive respectively from the outputs of the elements And 2 and And 13 at the moment when their inputs are pulsed and from the converter of pulses 3, at the input of the element 12 there is a signal and from the converter of 2 signals, a pulse is given and there is no pulse P. Signals from the signal converter U | come to the input of the element And 13, a pulse is applied and there is no signal P. The proposed device, as compared with the basic object, is simple, since the entire device is only implemented on the AND – NES logic elements, in which, along with the logic elements I, triggers, I, K, R, S, T - types, a delay element and a generator of single pulses are used. In the base object, it is necessary to use four input control signals from element 14, from input -7 and R, S-inputs. In addition, complex interconnections must be made between the elements in the base object; And the proposed device operates at any frequency of the supply voltage without prior tuning and restructuring of the elements.

The absence of the output signal in the base object should show reverse phase interlacing, however, this signal is also characteristic of the malfunctioning state of the base object (phase failure, malfunction of the device itself), which leads to a false positive of the entire device of the base object.

The increase in reliability in the proposed invention is achieved by the fact that during the forward and reverse phase rotation, the corresponding signals appear, the absence of which indicates a fault in the power section or the device itself.

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Claims (1)

A DEVICE FOR 'PROTECTING THREE-PHASE LOADS FROM CHANGING THE PHASE ALTERNATION AND PHASE INTERRUPTION, containing, according to the number of phases, three converters of sinusoidal network voltage signals into rectangular pulses connected with AND and NOT elements, and an actuating element, characterized in that, in order to increase reliability, the output the first converter of the sinusoidal signal of the mains voltage into rectangular pulses is connected to the second input of the second. element AND and the input of the first element NOT, the output of which is connected to the first input of the first element AND NOT, the output of which is connected to the first input of the first AND element, whose output is connected to the input of the third element NOT, the output of which is connected to the second input of the first AND element, the output of the second converter is connected to the second input of the first AND element and the input of the second element NOT, whose output is connected to the first input of the second AND-NOT element, the output of which is connected to the first input of the second AND element, whose output is connected to the input of the fourth element NOT, the output of which is connected to the second input of the second AND-NOT element, the output of the third the educator is connected to the first inputs of the third and fourth elements AND, the second inputs of which are connected respectively to the outputs of the first and second elements NOT, the third inputs of the third and fourth elements NOT, the third inputs of the third and fourth elements AND are connected respectively to the outputs of the second and first voltage converters, fourth the inputs of the third! And the fourth elements AND are connected respectively to the outputs of the first and second elements I. 108969?