SU1275632A1 - Device for protection of electric installation against phase loss - Google Patents

Abstract

The invention relates to the field of electrical engineering - relay protection and can be used to protect an electrical installation from operating on two phases. The purpose of the invention is to increase hardware reliability. The device contains a measuring unit consisting of a symmetric star 2, resistors and a measuring unit 3 consisting of two series-connected resistors and a capacitor and a rectifier 4, which, like the mentioned resistors, is connected to the phases of the mains supply. The output of the rectifier 4 is connected to the zener diode 5 and a capacitor 6 and a circuit consisting of triode 7 and a winding of relay 8 connected in parallel with it. The common point of the Zener diode 5, capacitor 6 and emitter of triode 7 is connected to the output of a symmetric star 2 consisting of resistors . A diode 10 is connected between the emitter and the base of the triode 7. To the anode of diode 10, one output of KOHOjeH 9 is connected, the second output of which is connected to the cathode of diode 10 via resistor 11 and zener diode 12 through diode 13 of pris diode 13 (L is single to midpoint block 3. The loss of hardware reliability is achieved by introducing the aforementioned Zener diodes 5 and 12, resistors in block 3 and resistors 11, and capacitors 6 and 9. 1 ill.

Description

The invention relates to electrical engineering, and in particular to devices for protecting an electrical installation from phase failure.

The purpose of the invention is to increase hardware reliability.

The drawing shows a circuit diagram of the device.

The device contains a block c. actuator 1, a measuring unit, consisting of two blocks 2 and 3, Yu rectifier 4, Zener diode 5 ,, capacitor 6, transistor 7, relay 8, capacitor 9, diode 10, resistor 11, second zener diode 12 and second diode 13.

Block 2 of the measuring node 2 is made in the form of a symmetrical star from the first, second and third resistors. Block 3 of the measuring unit consists of a series-connected first capacitor with a fourth and fifth resistors.

The device operates as follows.

With a full-phase mode of operation and the correct phase sequence, the voltage of the rectifier 4 stabilized by a zener diode 5 and filtered by a capacitor 6 is applied to a circuit consisting of a series-connected transistor 7 and a relay coil 8. With correctly selected parameters of the elements of block 3, the potential difference between the artificial zero point of block 2 and the cathode diode 13 is equal to zero, which excludes the flow of current through the base of the transistor 7.

The transistor 7 is in a cutoff state, and therefore the relay 8 is de-energized. To protect the transistor from breakdown in the absence of a signal at the base, the emitter-base junction is shunted by diode 10. The NC contact of the relay, which is located in the coil circuit of the power contactor (not shown), prepares its control circuit for switching on. When one of the phases breaks or their rotation is incorrect, the equality of potentials at the indicated points is violated. 'In one of the half-periods of the appearing voltage, a current flows through the circuit, consisting of a capacitor 9 and a diode 13, leading to a charge on the capacitor. When the voltage on the capacitor 9 exceeds the stabilization voltage of the zener diode 12, through the emitter-transistor '7, the resistor 11,

1275632 2 zener diode 12 and diode 13 begins to flow the base current of the transistor 7, which leads to the unlocking of the latter and the inclusion of relay 8.

The NC contact of relay 8 violates the power circuit of the winding of the power contactor .. The contactor is disconnected, removing voltage from the electrical installation and the protection device. A new inclusion of the contactor occurs only after pressing the Start button. The resistor 11 limits the base current of the transistor 7 and the zener diode 12. The diode 13 protects the emitter-base junction from the reverse voltage that occurs during abnormal conditions. The rectifier 4 receives power through a capacitive divider 14.

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The device can be widely used in installations powered by mobile power plants in difficult operating conditions, under which. Frequent breaks in the phases of cables and power lines, as well as errors in the phase rotation are possible. The device scheme involves connecting a protection device after the contactor (the option of switching on 30 load terminals is possible), which allows you to simultaneously control the operation of the contactor.

Claims (1)

The invention relates to electrical engineering, in particular, to devices for electrical installation protection against phase failure. The purpose of the invention is to increase hardware reliability. The drawing shows an electrical principle cxeNU. devices. The device contains a block with an executive element 1, a measuring node consisting of two blocks 2 and a rectifier 4, Zener diode 5, capacitor B, transistor 7, relay 8, capacitor 9, diode 10, resistor P, second Zener diode 12 and the second diode 13. Block 2 of the measuring node 2 is made in a B1-symmetrical star of the first, second and third resistors. Unit 3 of the measuring unit consists of a series-connected nerve capacitor with fourth and fifth resistors. The device works as follows. With full-phase operation and correct phase rotation, the voltage of the capacitor 4 stabilizes: the viral Zener diode 5 and filtered by the capacitor 6 is applied to the chain consisting of a series-connected transistor 7 and the relay 8 winding. When the parameters of the elements of the block 3 are correctly selected, the potential difference between an artificial loop and . The point of block 2 and the cathode of diode 1 is zero, which prevents current from flowing through the base of transistor 7. Transistor 7 is in a cut-off state, and therefore relay 8 is de-energized. For a transistor from the NRBO, if there is no signal at the base, the emitter-base junction is shunted by diode 10. A breaker contact which is located in the coil circuit of the power contactor (not shown), prepares its control circuit for switching on. With the break of one of the phases or their incorrect alternation, the equality of potentials of ales in the indicated points is violated. B OD1-1N from half-periods of the highest voltage across the circuit consisting of capacitor 9 and diode 13. A current flows, which leads to the charge of the capacitor. When the voltage on the capacitor 9 exceeds the voltage from the voltage of the Zener diode 12, the emitter-transistor 7, resistor 11, Zener diode 12 and diode 13 begin to flow the base current of the transistor 7, which leads to unlocking the latter and turning on the relay 8. Breaking relay contact 8 interrupts the supply circuit of the winding of the ci-stitch contactor. The contactor is turned off,. removing electrical installation and protection devices. A new on-time contactor appears only after pressing the Start button. Resistor 11 limits the base current of the transistor 7 and Zener diode 12. Diode 13 protects the emitter-base junction from the reverse voltage that occurs during abnormal conditions. Rectifier 4 is powered through a capacitive divider 14. The device can be widely used in installations strung from non-movable power plants in difficult operating conditions, under which frequent breaks in the phases of cables and power lines, as well as errors in phase rotation, are possible. The device circuit assumes connection of a protection device on the contactor (the option of switching to the load terminals is possible), which allows controlling the operation of the contactor simultaneously. Claims Device for protection of electrical installation against phase failure, containing a measuring node, diodes, first, second and third resistors, first, second and third capacitors and an actuator, characterized in that, in order to increase hardware reliability, it is additionally equipped with two zener diodes, the transistor, the fourth, fifth and sixth resistors, the fourth, fifth and sixth capacitors, the measuring node is made in the form of a symmetric star consisting of the first, second and third resistors connected to the phases; w of the network, and a chain connected to the two phases of the network; ki of the first capacitor connected in series with the fourth and fifth resistors, the steering point of the symmetric star connected to the common cathode point of the first zener diode, the second and third condensate 3 12756324 the emitter of the transistor and the cathode of the fourth resistor and the first diode, the anode of which is a connecting capacitor, the collector is transited to the junction point of the transistor base through the winding of the executive torus and the sixth resistor, another you-relay is connected to the connection point the waters of which are connected to the cathode of the second-j minus the mitel with the anode of the primary zener diode, the anode of which with the second zener diode and the lining of the second It is one with the common point of the second-capacitor output, and the rectifier of the diode and the third capacitor is through the fourth, fifth and sixth the cathode of the second diode is connected to a common capacitor to the phases of the network.