SU1525800A1 - Device for shorting protection of dc contact-wire network - Google Patents

Abstract

This invention relates to electrical engineering and can be used to protect direct current grids. The aim of the invention is to increase the sensitivity of the protection. When starting an electric rolling stock or increasing the load at the output of the differential scale amplifier 15, the positive voltage increases, which charges the capacitor 18. This voltage goes through the emitter follower 22 to the direct input of the comparator 10 and coarsens the protection, the greater the greater the preceding short circuit feeder load current. 1 hp f-ly, 2 ill.

Description

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The invention is not related to electrical engineering and can be used to protect direct current grids from short circuits. In particular, it can be used at traction substations and section posts of electric direct current railways.

The aim of the invention is to increase the sensitivity of the protection.

Fig, 1 is depicted functional. The device diagram in FIG. 2 - timing diagrams that explain his work during a short circuit without a preceding load “—and with a previous load.

The protection device (Fig. 1) contains measuring shunt 2 connected to the positive bus 1 t of the substation, switched between the positive bus and the high-speed switch 3 connected to the feeder of the contact network 4, resistive divider 5 connected by one output to the negative bus 6, and the other output through a series-connected Zener diode 7, an additional resistor 8 and a potentiometer 9 for setting the setpoints to one output of measuring shunt 2, a comparator 10 connected by a direct input to another output of the measuring foot-by shunt 2, and an inverse input ohm. to the adjustment output of potentiometer 9 setpoint, zero-id torus 1 1 ,. the output connected to the output of the comparator 10, the null indicator 11 is connected via series-connected element 12 of the time delay 1W and the amplifier 13 to the output of the element 14, a differential scale amplifier 15 connected to the direct and inverse inputs parallel to the measuring shunt 2, and output through serially connected load 16, bit 17 resistors and capacitor 8 to the midpoint of the converter. 19 power supply, two diodes 20 and 21, the emitter follower 22 connected by the input to the common point of the resistor 17 and the condensation IB, and the output to the direct input of the comparator 10, is a setpoint change switch 23 and a shunt resistor 24,

The output element 14 may be implemented as a high-voltage relay 25 with a storage capacitor 26, a thyristor switch 27 receiving power from the source 28 of the operating voltage and the closing contact 29

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jQ 25 d d,

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a relay 25 included in the control circuit of a thyristor switch 27.

The device works as follows

With a short circuit in the contact network, the current of the feeder increases with a rise rate determined by the inductance of the reactor of the substation and the traction network to the point of short circuit (curve 30 in Fig. 2), the resistance of the traction network drops (curve 31), when it reaches the value of the setpoint at the output of the comparator 10 appears positive, the potential, the null-indicator II, the time delay element 12 and the amplifier 13 (curves 32, 33, respectively) are activated. Then contact 29 of the high-voltage relay 25 closes and opens the thyristor switch 27, by disconnecting the fast-acting switch 3, Relay 25 is triggered by an exertion accumulated in the capacitor 26 even despite a sharp landing of the supply voltage, for example, when a short-circuit is close to the traction substation, as the short-circuit current rises quickly, - the capacitor 18 does not have time to charge and the protection setting does not change,

Under normal load and during the launch of an electrically mobile: HO composition, the feeder current increases slowly as the train accelerates (curve 34). At the output of the differential scale amplifier 15, as the current increases, the positive voltage increases. The capacitor 18 charges (curve 35). This voltage goes through the output repeater 22 to the direct input of the comparator 10, and it can only work ; With a higher feeder current, t, e, with less resistance, the send setting is deepened by the larger, the more the feeder load current preceding the short circuit (curve 36).

If, after a large load, it drops abruptly: and after this a short circuit occurs (curve 37) j, the capacitor 18 is quickly discharged through the shunt-diode 21 and the resistor 16 to a voltage at the output of the scale amplifier 5 corresponding to the residual feeder load (curve 38) , Degree protection is removed, and it works with a normal setting (curve 39},

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If the load is not reset and then a short circuit occurs (curves 40, 41), the total feeder current in this case is composed of the remote short circuit current - and part of the load current - and still the resistance reaches the protection setting taking into account its depth. Protection triggered (curves 42, 43),

For the possibility of changing the setpoint, the potentiometer 9 of the setpoint and the additional resistor 8 are bridged by a circuit from the series-connected setpoint switches 23 and the shunt resistor 24, energized when changing the partitioning system of the catenary;

Claims (1)

Invention Formula 1, A short-circuit protection device of a direct-current contact network containing a current sensor made in the form of a measuring shunt, one output of which is connected to the terminal for connection to the positive bus of the substation, and the other output of the measuring shunt is connected to the terminal for connection to the high-speed switch, voltage sensor, made in the form of a resistive divider connected by one output to the terminal dp of connection to the negative bus under station, and another output - to the anode of a Zener diode connected by a cathode to one output of a potentiometer for setting a set, the other output of which is connected to one output of a measuring shunt, a comparator connected by a direct input to another output of a measuring shunt, and an inverted input to an adjustment output the setpoint potentiometer, a null indicator, the input of which is connected to the comparator output, and the output of the zero indicator is connected via 0 five 0 five 0 five 0 45 a series of time delay elements and an amplifier to the output of the output element, and a power converter connected in parallel with the aforementioned Zener diode, which is different (that, in order to increase the sensitivity, a differential scaling amplifier, load and discharge resistors, a capacitor, two diode and emitter follower, with the direct and inverse inputs of the differential scale amplifier. connected in parallel to the measuring shunt, the output of the differential ma the head amplifier is connected via series-connected load and discharge resistors and a capacitor to the middle point of the power converter, to which is also connected the anode of a single diode connected by a cathode to the common connection point of the load resistor and the discharge resistor in parallel with which the second diode is connected, the common connection point of the capacitor and the discharge resistor is connected to the input of the emitter follower, the output of which is connected to the direct input of the comparator, 2, The device according to claim 1, 1 and 2, so that, in order to increase the stability of the operation when changing the separation circuit of the contact network, the zener diode cathode is connected to the output of the setpoint potentiometer via an additional resistor, the resistance of which is by an order of magnitude greater than the resistance of the potentiometer; W f 32 33 3H 35 36 Ry 37 38% 39 40 W% VZ V3