SU1037372A2 - Apparatus for protecting electric machine - Google Patents

Description

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Sxo8 mixer ctiCfMtw Cutftoff per switch Shchflfc Figure 1 The invention relates to electrical engineering, in particular, to devices protecting electrical machines from emergency operation, and can be used, for example, to protect electric machines of electric movable composition against circular lights and short circuits . According to the main auth. No. 989656 a device for protecting electric machines from emergency operation is known, which contains voltage sensors connected in parallel to the input terminals of an electric machine and connected to pulse generators according to the number of electric machines connected to comparison units made in the form of three triggers, two-input elements And and one of the main element OR, and the input of each controlled pulse generator is connected to the output of the voltage sensor, the outputs of the first and second controlled pulse generator under They are connected to the separate inputs of the first trigger, the outputs of the third and fourth pulse generator are connected to the separate outputs of the third trigger, in addition, the outputs of the mentioned generators are connected, respectively, to the output of the second and third generator, which are also connected to the first inputs of the And elements, the second inputs which are connected to the outputs of the second trigger, and the outputs of all elements And are connected to the inputs of the differential frequency selection block, the other input of which is connected to the reference frequency generator, and the block is allocated differential frequency contains additional elements, OR by the number of channels, mixing blocks. Frequencies, to one input of which the generator of reference frequencies is connected, to the other outputs of additional elements OR, each of which is connected to the output of two AND elements of one channel, and outputs of blocks Mixing Frequencies are the inputs of the main element OR Cll. However, as practice shows, the collector surface is not ideally even and with the same resistance of the incident and running along the edges of the brush-and, which leads to the formation of single sparks, not a characteristic transition of the machine to emergency mode. However: this device perceives this mode of operation as an emergency mode, which is confirmed by the oscillogram1 "5th" shown in FIG. 1. In this case, from the output of the emergency mode detection system, a signal is sent to the actuator thyristor, which leads to a false positive of the power devices, which disconnect the power circuit from the power source. The aim of the invention is to increase the efficiency of protection of electric machines by eliminating sensitivity to single sparks. The aim is to ensure that the device for protection of electric machines from emergency operation is additionally equipped with a pulse counter, one input of the counter connected to the output of the reference frequency generator, the second input to the output of the main element OR, and the output of the counter serves as the output of the device. Such an embodiment of the device makes it possible to eliminate the effect of single accelerations on the operation of the protection, since the additional counter is reset to its initial state after each reference frequency period and does not allow the accumulation of signals arriving at its input during single sparks. In the case of circular fire or short circuit, the scan at the output of the main element OR shows a series-imp / tho, which leads to the filling of an additional counter and to the appearance of alarm mode. FIG. 1 shows diagrams of processes in the elements of a known device; FIG. 2 is a schematic diagram of the proposed device. The diagram in FIG. 1 shows the signals G, 1, G ,,, GF at the output of the generators of the prototype and at the input and output of the mixer. The device contains a box of 1-4 four electric machines. For example, car meters or tram or other EPS. Sensors 5–8 of the Korea voltage are connected in parallel to the core, each of which is connected to one generator 9–12, respectively, whose output frequency is proportional to the voltage of the voltage sensors. The generators 9 and 10 are connected to separate inputs of the first trigger 13 and to one two-input elements 14 and 15 And, to the other inputs of which are connected the separate outputs of the second trigger 16. The separate inputs of the second trigger are connected to the outputs of the second and third generators 10 and 11, the outputs of which are connected also to the same inputs of the elements 17 and 18 I. Separate inputs of the third trigger 19 are connected to the outputs of the third and fourth generators 11 and 12, which are also connected to one input of elements 20 and 21 And, the second inputs of which are connected to separate the outputs of the third trigger 19. The outputs of all, elements 14, 15, 17, 18, 20, 21 And connected to. the inputs of block 22

differential frequency allocation, to another input of which the reference frequency generator 23 is connected, and leaving the differential frequency selection block 22 is connected to the main element 24 OR, the output of which is connected to one input of an additional counter 25, the second input of which is connected to the reference frequency generator 23, and the output counter 25 is connected to the actuator (not shown).

The device works in the following way.

When voltage is applied to electrical machines, the output of sensors 5-8 begins to produce voltage, which is applied to generators 9-12 whose frequency of operation is proportional to the voltage applied. As the electric machines start, the voltage applied to the machines increases, which leads to an increase in the frequency of operation of the generators 9-12. In the absence of a circular VOLUME across the collector or the transfer of an electric arc on the body, the frequency of operation of the generators must be equal, since the same voltage is applied to the 1-4 core. With the output of generators 9-12 pulses come on. separate entrances .trigger. 13, 16, 19. At the same frequencies, the flip-flops will switch symmetrically, thereby prohibiting the arrival of pulses to the difference-frequency allocation unit 22 through one of the elements 14, 15, 17, 18, 20, 21 I. However, taking into account that there is always The reset of the parameters of korea and generators, the frequency of operation of generators 9-12 will not be equal. Therefore, in separate modes of operation, the difference 22 will be received at the output of block 22, one of the elements 14, 15, 17, 18, 20, 21 of each channel. These pulses, arriving at the inputs of the difference-frequency allocation unit 22, are compared with the frequency of the generator 23 reference signals. Taking into account that in normal operation the value of the difference frequency will be lower than the frequency of the generator 23 reference frequencies, at the output of block 22 there will be no pulses of the second frequency difference.

However, in the case of single sparks in the collector of the throttle, single pulses will be received at the input of the trigger 13, 16, i-y, the frequency of which will differ, and these pulses can immediately follow the pulse of the generator operating in normal mode. Therefore, such a sequence of impulses is perceived. It is passed by mixer 22 as following a pulse cf by a high following frequency, which is falsely perceived as

0 emergency mode, since the follow-up period of these signals is significantly less than the follow-up period of the reference frequency generator pulses. When connecting the counter 25 to the output

5 of element 24 OR this signal or several signals are sent to one counter input, which leads to a change in its state and to a delay of single pulses. Through the period

0. Following the pulse of the generator 23 of the reference frequencies, the counter 25 again returns to its original state, thereby writing off the number entered in it. Counter Size 25

5 should be chosen based on the acceptable normal degree of arcing in service. So, for metro cars, its width is one or two. In the event of an emergency, a sudden

0 a decrease in voltage at a short-circuited crust, which leads to the appearance at the output of a block 22 of a differential frequency, the value of which exceeds the frequency of the generator 23 of the eta5 frequency. This excess results in the appearance of a frequency at the output of the OR element 24, which, arriving at one input of the counter 25, leads to its filling. When filling

At the counter 0, a signal appears at its output 25, which then follows the actuator.

Changing the frequency of the oscillator 23 of the reference frequencies, changing the sensitivity of the device, and changing the difference in the counter 25, changing the controlled number of single sparks. Thus, in this device for the protection of electric machines, it is possible to increase the efficiency of the shock motor engines by eliminating spurious protection processes caused by single

5 sparks across the collector of an electrical machine.

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Claims (1)

DEVICE FOR PROTECTION OF ELECTRIC MACHINES according to ed. St., No. 989656, characterized in that, in order to increase the efficiency of protection of electrical machines by eliminating the influence of single sparks in the collector, it is additionally equipped with a pulse counter, one input of which is connected to the output of the reference frequency generator, another input - to the output of the main element OR, and the output serves as the output of the device. ’ Jf a ........... O ’............ \ ·. · · „ .............................. _e # r ₃  * ¹¹¹ t . Guy ....... -----·-------1 RF Input Mixers Vym8 system Signal to thyristor ----------------------------------- Figure 1 t .SIU 1.037372