SU1314411A1 - Method of protection of three=phase using equipment against emergency operation conditions - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to expand the functionality. This is achieved due to the fact that the difference between the monitored and reference signals, obtained on the G transistor amplifiers 4, 5, is formed as difference signals, in one of which the monitored signal is proportional to the amplitude value of the current of the first phase, the charging capacitor 12, the other is proportional to the amplitude value of the current of the third phase, which charges the capacitor 13, and as a reference value, choose a signal proportional to the instantaneous values of the minute of the stabilized current of the second phase, oluchaemy through a current transformer 2, a diode 11, resistor 10 and zener diode 9. When exceeding any threshold value of the resulting differences in the windings of the relay 16 or 17 receive an output signal that causes one of the two srabatshanie. winding relay 18 or 19. 2 Il. o (L e 4 4 fig. g

Description

The invention relates to the protection of consumers from accidental operating conditions and can be used to improve the level and safety of operation of current collectors in. three-phase electrical networks x.

The purpose of the invention is to expand the functionality of the security device,

FIG. 1 shows the electrical circuit of the protection method; in fig. 2 - diagram of temporal characteristics of one of the generated differential signals (for example, A, B) proportional to the amplitude value of the current of one of the network phases (A) and proportional to the instantaneous value of the rectified stabilized current of the other phase of the network (B).

A device for implementing the indicated method contains transformers 1, 2, and 3 currents to which two transistor amplifiers 4 and 5 are connected. The input of both amplifiers 4 and 5 is bridged by diodes 6 and 7, respectively, which are connected in series and through a resistor 8 are connected to the zener diode 9. At the same time, the zener diode 9 through a resistor 10 and a diode 11 is connected to a current transformer 2. The collectors 12, 13 and diodes 14 and 15 are connected to the collector of these amplifiers, respectively, windings 16 and 17 of a two-winding relay, the second windings of which 18 and 19 Connected to capacitors 20 and 21 "In this case, a capacitor 20, which is a power source for transistor amplifier 4, is connected via diode 22 to a current transformer 1, and a capacitor 21, which is connected to a power source for amplifier 5, is connected via a diode 23 to transformer 3 currents. The windings 16 and 17 of the two-winding relays are shunted respectively by capacitors 24 and 25. In the collector circuits of transistors 4 and 5, respectively, load resistors 26, 27 are included, and adjustable resistors 28 and 29 are connected to the base circuit. In parallel, resistors 26 and 27 are connected through capacitors 12 and 13, respectively, are connected diodes 30, 31.

The device works as follows.

During normal operation through the input of transistor amplifiers 4

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and 5 flows the current difference between Igr proportional to the instantaneous value of the rectified stabilized current of phase B and current 1, 5 proportional to the amplitude of the current, phase A, and phase C. When the amplitude value of current 1 exceeds the instantaneous value of current I

at

transistors 4 and 5 open, and when 0 1 - 1 transistors 4 and 5 are closed (respectively t, tg is the duration of the open and closed state, Fig. 1). In this case, when transistors 4 and 5 open, the capacitors 12 and 13 are charged.

When transistors 4 and 5 are closed, capacitors 12 and 13 are discharged through diodes 14 and 15, and resistors 26 and 27, the windings of relays 16 and 17.

20

25

Consequently, currents due to periodic discharge pulses of capacitors 12 and 13 flow through the windings of relays 16 and 17 in the normal operation of the device.

At the same time, currents from capacitors 21 and 20 flow through the other windings 18 and 19 of the two-winding relays. As the windings are turned on. According to the compensation circuit, the resulting magnetic flux in the magnetic circuit of both relays is zero, the relay doesn’t accept the switches. affecting the circuit-breaker, which disconnects the emergency network, are not closed. In the event of an emergency as a result of a short circuit,

1-shee of the phase failure of the network current 1 exceeds

sew current 1 and transistor or one

(koz. between phases AB or BC, termination of phase A or C) 3 or both transistors (three-phase short circuit, short circuit between phases A and C, interruption of phase B) opens. As a result, the current through the winding 16, or through the winding 17 or through both disappears immediately. There is a response, respectively, of one of the two-winding relays from the current through the windings 18 and 19 or both simultaneously. The monitored network is turned off using a circuit breaker (not shown).

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The pick-up setting of the device is controlled by resistors 28 and 29, which set the corresponding base current of transistors 4 and 5.

313

The device provides a protective failure, i.e. produces disconnection from the network in case of defective elements of the electrical circuit. Indeed, when the elements are intact, the transistors of the device must periodically open and close. Capacitors charge and discharge. The integrity of the device’s electrical circuits must be maintained. Otherwise, the difference signal of a rectangular shape is missing. As a result, either one or two double-winding relays are activated.

Thus, this method of protection of three-phase consumers from emergency operation allows the functionality of the protection to be expanded, since it protects against both incomplete-phase operation and short-circuit currents. At the same time, a self - monitoring of the health of the elements of electrical circuits that implement its protection devices is ensured, which increases the reliability and safety of operation of electrical networks with the offered protection.

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Claims (1)

Invention Formula Protection method - three-phase consumers from emergency operation, based on the formation of the difference between the monitored and the reference signal, when the threshold value is exceeded, an output signal is obtained, characterized in that, in order to expand the protection functionality, the difference is formed as two difference signals, in one of which the monitored signal is proportional to the amplitude value of the first phase current, in the other, it is proportional to the amplitude value of the current of the third function, and as a reference signal, when forming both difference signals, a signal proportional to the instantaneous It is the maximum of the stabilized current of the second phase, and the first difference is compared with the signal proportional to the amplitude value of the current of the third phase. Threat, and the second difference with the signal proportional to the amplitude value of the current of the first phase, and if any of the obtained differences exceeds the threshold value, an output signal is obtained. Compiled by T. Shchegolkova Editor M. Tovtin Tehred A. Kravchuk Order 2216/53 Circulation 619 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Design, 4. fiyo.2 Proofreader E. Roshko