SU1257736A1 - Device for programmed automatic reclosing of electric motors - Google Patents

Abstract

The invention relates to electrical engineering and can be used to automate power supply systems of industrial enterprises. The purpose of the invention is to reduce the total, recovery time of the previous mode and increase the efficiency of electric motor re-start by taking into account the requirements of the technological process for the order of automatic re-activation (IW). This is achieved through the introduction of a turn-on selection block 9, a block 10 with no starting current in the power inputs and reset cells 3 and 4. At the same time, block 9 consists of elements OR NOT 11-13, logical 14th threshold, logical 15th threshold, element 16 OR -NON, where the pit setpoints of thresholds 14 and 15 are determined by the load capacity of the OR 17–20 logical element node. This allows you to automatically select the optimal, pre-calculated VA (L NO SL O9 Od

Description

The sequence of switching on the motors depending on the initial conditions that had been lost, and the time for the next command to turn on is dependent on the load. The invention relates to the automation of power supply systems of industrial enterprises, namely, automatic restarting devices (AR) of installations with continuous technological process

The purpose of the invention is to reduce the total recovery time of the predecessor mode and increase the efficiency of electric motor re-start by taking into account the requirements of the technological process to the priority of automatic reclosing.

The drawing shows the block-scheme of the proposed device.

The relationship between the engines of one group can be determined by production technology. If there are several groups of electric motors that receive power from one node of the electrical network, the TO of the device is supplied with intergroup communications.

The block diagram of one engine control channel is shown in detail, and the remaining channels are similar,

The device contains in the control channel of each engine a block 1 for fixing the motor shutdown protection against power loss, block 2 for time, cells 3 and 4 for reset, sensor 5 for voltage on supply tires, element 6 Delay, logic element 7, output unit 8, as well as common on the group of interconnected engines, block 9, the selection of the sequence of switching on and block 10, the absence of starting current in the supply inputs. Block 9 consists of the first elements YLI-NOT 11-13, the logical 14th threshold, the logical 15th threshold, e ,:, the OR-NOT 16, where the values of the setpoint of the thresholds 14 and 15 of the pit are determined by the load capacity of the node of the logical elements OR 17- 20.

ability of the node electrical network, which in turn depends on the mode of operation of the power supply system. 1 il.

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The device works as follows.

The fixing unit 1 is activated and self-holding in the actuated state only if the protection against the loss of power to the electric motor is triggered and at the same time the engine is turned off.

Block 2 of the timeout of the output time forms a permitting impulse, the front of which lags in time from the moment the unit 1 responds by a value of the minimum permissible time delay of the automatic reclosing. The end of this pulse (cut) determines T, the maximum permissible time of AR. For each electric motor, both T „„ „and T„ „are calculated in advance,

The minimum reclosure time for a synchronous motor is determined by the stator field quenching time to a value at which asynchronous switching of the motor is allowed. For asynchronous motors, T may be zero. Maximum reclosure is limited either by the technological features of the production or by conditions of safety. With identical electric motors, the 2 time delay block may be common.

The reset cell 3, as well as the single cell, 4, which is named for it, forms a short pulse at the output, which removes the latching unit 1 from self-holding. A reset pulse is generated at the time of termination (at the cut) of the control pulse applied to the input of the reset cell. Sensor 5 triggers and generates an enable signal when the operating voltage is applied to the tires supplying this electric motor. If several engines are powered by several tires, the sensor 5 may be rims.

Element 6 triggers a time delay in transmitting the enable signal from sensor 5.

When triggered, the output element 8 turns on the electric motor of its control channel and simultaneously sends a pulse to the input of the reset cell 4. At the cut of this pulse, a short reset pulse is formed by the cell 4.

The power-on sequencing unit 9 adjusts the sequence and number of simultaneously activated electric motors, taking into account the technology and depending on the total number of emergency shut-down motors of this node of the electrical network.

The purpose of the block selection sequence is as follows.

The load capacity of the Elek-20 unit Combinations of operating and standby

Often, it is often not possible for several powerful electric motors to simultaneously turn at once. In such cases, it is advisable to turn on the motors in turns, not exceeding the maximum allowable number of simultaneously turning on motors in each turn. At the same time, it is necessary to take into account the technological features of production when choosing the priority of the next priority of switching on the engines of this production line.

In the general case, the first should turn on the previous one, and the second and third should follow the next one by the number of electricity. engines, counting them from the end of the processing line to the top. If there are two or more production lines, the following sequence of switching on is necessary in all Q lines.

In case of short-term disturbances of external power supply, the power can be lost either to the entire network node, or only to a part of it. Therefore, 45 the number of accidentally disconnected electric motors is probable. character In addition, part of the engines of a single process line may be in reserve when restoring the pre-emergency circuit, the backup engines should not affect the sequence and time of the command for the next switching of the working engines. 55

In the drawing, in the contour surrounded by a dotted line, the functional diagram of the block 9 for selecting the sequence is shown.

The left and right of the diagram shows the inputs and outputs of the block selection sequence, the number of which can be any, equal to n group of interconnected electric motors of one production line. The number of groups of electric motors (the number of technological lines) can also be any, but all of them are interconnected by intergroup communications.

Let us consider the principle of operation of the block for choosing the sequence in the following concrete example.

There are two process lines, each with an electric motor. At the same time, two or three electric motors in each line can be operated, the remaining electric motors are in reserve.

engines can be any. All electric motors are powered by a common electrical node. For a successful self-start, the network node allows you to simultaneously turn on no more than two electric motors. In this case, it is assumed that, in addition to the data of the electric motors, other responsible electric motors are powered from the common node of the network, which are not disconnected from the network in the event of a short power failure, but go to self-starting. For this case, the logical threshold 15 is assumed to be 3 out of 4, i.e., m 3, p 4. This means if a logical unit appears at the output of threshold 15 only if logical units are fed to any three or more the entrance. Logical threshold 14 is applied 1 of 4 and in the particular case acts as

element OR. I

In the initial state, there are no signals on all inputs 1.1-1.P of the block for selecting the sequence, i.e. logical zeros (4) are given. At the outputs of thresholds 14 and 15, zeros appear. If there are also no input signals on the second production line, then the inter-group communication to the second input of the element 16 is fed to zero. At the output of element 16, a logical unit appears. Since elements 17-20 pass to the output unity from their inputs, units appear on all outputs 7.1.1-7 in block 9.

If on any two inputs 1.1-l.n of the first technological line in TC

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units, then on the same line at the output of element 16 the signal will not change. Consequently, block 9 will not render and there will be a simultaneous automatic reclosing of two electric motors that are turned off at once, which does not contradict the given condition. If on the first line more than two motors were disconnected, then at the output of the logical threshold 15 there is one unit of rotation, and at the output of element 16 - zero.

Now the signals at the outputs of block 9 will depend on the second information inputs of the elements OR 17-20. The logic on the elements OR-NOT 11-13 is constructed in such a way that the priority for the initial activation of 1-1 is the engine with the lowest order number, i.e., the previous one. If there is a first motor among the disabled ones, then logical unit is at the output of element 17, and logical zeros at the outputs of elements 18-20, since elements 11-13 will be closed from the signal (logical unit) at input 1.1 block 9. After switching on the first engine at input 1.1, a logical zero is passed, the output of element 16 is one, and secondly, the two remaining engines are turned on at the same time.

If during a power outage, for example, two engines on the first technological line and at least one motor on the second 5 process lines were disconnected, then the output of the logical threshold 14 of the second process line is one unit. This intergroup communication signal will affect the element 16 of the first line and its output is zero. As a result, on the first line, the activation signals will be given depending on the engine's sequence number. At the same time, suppose that the first line had an emergency shutdown, for example, the W 2 n No. engines (). Then the logical units, first of all, are in vehicle at outputs 7.1 and

No. 2) may be switched on first, second, and simultaneously with any of the engines in: first or second, depending on the situation and emergency mode. The specified process conditions are respected.

The AR scheme of the second technological line also works in the same way,

In general, in case of emergency shutdown of the fifth number of electric motors in each process line, first of all, with the minimum time, one younger motor in each line is turned on, and two engines, or one in each line, turn on in the second place. either immediately two in one line. This eliminates the possibility of simultaneously turning on three or more electric motors, the self-starting of which is impossible due to the condition of the load capacity of the electrical network node, thereby increasing the reliability of the production lines in comparison with the known devices of group automatic reclosing

Block 10, the absence of inrush current in the power inputs, is intended to regulate the time delay of the AOB between the lines. At all the outputs of block 10, a permissive signal (logical unit) appears only if there are no inrush currents caused by self-starting electric motors in any of the supply inputs.

The starting current of the electric motor is easy to distinguish from the nominal value of its multiplicity. At the same time, the current threshold organs included in the current transformer circuit of the power inputs are used as the measuring organs of the unit 10. The contact sensors of these organs are interconnected according to the OR scheme and control the operation of unit 10. It is inefficient to use voltage measuring organs for the same purpose to respond to a decrease in the voltage on the plugs.

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7.2. Consequently, first and foremost, the minimum operating voltage of engine no. 2, after that, at input 1.2, the signal disappears and the circuit for starting engine no. 4 is assembled secondarily. When, for example, engines No. 1 and No. 2 are switched off, the engine No. 1 first turns on, and then No. 2, Thus the same engine (in our examples the engine

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No. 2) may be switched on first, second, and simultaneously with any of the engines in: first or second, depending on the situation and emergency mode. The specified process conditions are respected.

The AR scheme of the second technological line also works in the same way,

In general, in case of emergency shutdown of the fifth number of electric motors in each process line, first of all, with the minimum time, one younger motor in each line is turned on, and two engines, or one in each line, turn on in the second place. either immediately two in one line. This eliminates the possibility of simultaneously turning on three or more electric motors, the self-starting of which is impossible due to the condition of the load capacity of the electrical network node, thereby increasing the reliability of the production lines in comparison with the known devices of group automatic reclosing

Block 10, the absence of inrush current in the power inputs, is intended to regulate the time delay of the AOB between the lines. At all the outputs of block 10, a permissive signal (logical unit) appears only if there are no inrush currents caused by self-starting electric motors in any of the supply inputs.

The starting current of the electric motor is easy to distinguish from the nominal value of its multiplicity. At the same time, the current threshold organs included in the current transformer circuits of the power inputs are used as the measuring organs of the unit 10. The contact sensors of these organs are interconnected according to the OR scheme and control the operation of unit 10. It is inefficient to use voltage measuring organs for the same purpose to respond to a decrease in the voltage on the plugs.

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 Since the minimum operating voltage is often comparable to the landing voltage during start-up, when the operating voltage on the tires is maximum.

Consider the operation of the device for software automatic reclosing of a group of electric motors with short-term power loss.

A part of the motors, when the power supply is lost during the operation of the automatic reclosing source of the working source or automatic switching on of the reserve (ATS) of the backup source, are not disconnected. These are mainly asynchronous electric motors of the most important mechanisms. Such motors are not connected to the software automatic reclosing device, but go to a razolozapusk when a voltage is generated. Synchronous motor protection is disconnected from synchronous voltage, preventing non-synchronous switching, and also asynchronous, simultaneous self-starting of which is impossible.

The power supply may disappear on one section of the substation bus, or on two sections at once. Since the number of simultaneously operating electric motors in different sections may be different, the number of accidentally disconnected engines is also random. If there are bus sections of tires, the range of zones of the number of possible outages expands.

In the control channels of the emergency shutdown engines, fixation blocks 1 are activated and, through time delay T, which is created by block 2, a logical unit is fed to the first input of the four-input element 7. At the same time, block 9 supplies logical units to the third inputs of the elements 7 of all control channels, except for those engines that in this situation must be included in the second and subsequent queues.

After the occurrence of voltage on the busbar supply sections, the corresponding sensors 5 are triggered, but the logical unit to the second input of element 7 is supplied with a certain delay t, carried out by element 6. Such a delay is necessary so that the automatic reclosing does not occur at the same time as the self-starting is not disconnected electric motors. During this delay, the starting current from the self-starting motors and unit 10 will prohibit the operation of all control channels for the duration of their self-starting.

If there are no disconnectable motors of the first stage on these buses, it will occur at time tj after applying voltage or after expiration of time T „„. At the same time, in the control channels permitted for AR control,

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output units 8 and the first-turn electric motors are turned on. From the starting current of these motors, unit Yu will operate and return all output organs to the initial state. At the time of the return of the organs (on the cut), using cells 4, short reset pulses will be generated, which will reset the fixing unit 1 of the already switched on engines. In this case, the information at the inputs of block 9 will change, and at the output of block 9 a circuit of the second AR phase will be assembled. However, switching on the motors of the second stage will take place after the logical unit is turned out at the output of unit 10, i.e. after reaching the nominal mode of the electric motors of the first stage of the automatic reclosing. And so sequentially, commands will be given for alternate switching on as soon as the start of the electric motors of the previous line is completed.

If, for any reason, the motor starts to pull, the voltage on the tires does not appear for a long time, then after a time using the rotary valve 3 all fixing blocks 1 will be reset and the device circuit will return to its original state.

The use of the new elements of the block for selecting the sequence, the block of no - starting current and reset cells favorably distinguishes the proposed device for software automatic reclosing from known devices for automatic reclosing of electric motors, since the proposed device automatically selects the optimal, pre-calculated version of the sequence of switching on the motors depending on the changed initial conditions, and the time of the next activation command is dependent on the load capacity of the electrical network node, which, in its alternate depends on the operating mode of the supply grid.

Claims (1)

Invention Formula A device for programmed automatic re-activation of electric motors, containing in the control channel of each engine a block for fixing the engine shutdown as protection against power loss, the inputs of which are used to connect to the sensor Protection against loss of power and to the switch position sensor is output through the time delay block connected to the first input of the four-input logic element I and to the input of the reset cell, the output of which is connected to the input of the engine shutdown lock protection block. feed tires, the output of which is connected to the second input of the AND gate through the DELAY element, and neither the total recovery time of the previous mode and the efficiency of the automatic re-start (ACB) of the engines by taking into account the requirements of the technological process and the AII-Bj sequence, the turn-on selection block, common to a group of engines, is introduced that has n inputs and outputs equal to the number of controlled motors the group, as well as the input and output of communication with the units for selecting the sequence of switching on other groups of engines the swarm is connected to the output of the output organ, and the output is connected to the input of the engine shutdown latching block by protection against power loss, n inputs of the block for selecting the sequence are connected to ti outputs of the motor shutdown latching blocks by protection against power loss of each engine in this group, and its communication input is connected to the communication outputs of the order of switching on other engines of other groups where m Editor Y. Sereda Order 5033/52 Compiled by N Panteleev Tehred L.Oleynik Proofreader A.Obruchar Circulation 612 Subscription VNIISH State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d, 4/5 Production-printing company, Uzhgorod, st. Project, 4 0 5 0 0 five the number of motors of other groups, the outputs of the block for selecting the sequence are connected to the third inputs of logic elements AND in the control channel of each motor in the group, and the output of the block with no starting current is connected to the fourth inputs of logic elements AND in the control channel of each engine in the group includes includes logical elements OR, the outputs of which are corresponding by number to the outputs of the power-on selection block, (p-1) of the first elements of the IPN-NOT, the first and second logical thresholds, Allowing simultaneous connection of motors, the number of which is determined by self-starting conditions, the inputs of which are connected to all inputs of the turn-on sequence block, the second element of the IPI-NOT first input of which is connected to the output of the first logic threshold, and the other input is connected to the outputs of the second logical thresholds of turn-on blocks other groups of engines, and the output is connected to the first inputs of logical elements OR, the inputs of the first elements OR-NB, the number of which is equal to their number, are connected to the corresponding numbers by To the inputs of the block for selecting the sequence, and the outputs to the second inputs of the OR elements, whose numbers are one more than the numbers of the corresponding first elements OR, the first input of the sequence block is connected to the first input of the first element OR, the output of the second logical threshold is connected to the inputs the second elements of the OR-NOT blocks the order of inclusion of other groups of engines.