SU1569856A1 - Device for registering service life of machines - Google Patents

Abstract

The invention relates to specialized information devices and can be used in production monitoring and metering systems or as a stand-alone device for monitoring the technical condition of machines, in particular, powerful electric motors of mechanisms drives operating in a wide range of non-stationary modes (frequent and delayed starts, self-starts with non-synchronous switching on, long overloads, etc.). The purpose of the invention is to increase the information content and accuracy of the device by taking into account the heating-cooling processes of the windings of the machine. The device contains sensors 1 ₁ ... 1 _N , keys 2 ₁ ... 2 _N , amplitude detectors 3 ₁ ... 3 _N , selector 4 maximum voltage, elements 5 ₁ ... 5 _N delays, functional converters 6 and 7, the recorder 8, the adder 9, the load sensor 10, the comparator 11 and the correction unit 12. Registrar 8 contains three registration channels, each of which consists of series-connected voltage-frequency converter 13, frequency divider 14, and counter 15. Correction unit 12 contains an adder, five keys, a HE element, two reference voltage sources, two amplifiers, two integrating elements and three current-limiting elements. The device makes it possible to predict the operation and determine the need for taking the equipment to preventive inspections and repairs, i.e. provides reduction of equipment maintenance costs. The operation according to the technical condition allows increasing the real service life of the equipment and increasing the reliability of the technological circuits. 2 hp f-ly, 3 ill.

Description

The invention relates to specialized information devices and can be used in production control and learning systems. This, or as an autonomous device for controlling the technical condition of machines, in particular, high-power electric motors drives mechanisms operating in a wide range of non-stationary conditions (Q modes, etc.).

The purpose of the invention is to increase the information content and accuracy of the device by taking into account the heating-cooling processes of the windings of the machine.

Figure 1 shows the block diagram of the device; figure 2 - functional diagram of the correction unit; on fig.Z - timing charts of the device in start mode.20

The device contains sensors 1 ... 1P, keys 2 ... 2P, amplitude detectors 3j | ... 3n, selector 4 of the maximum voltage, elements 54 ... 5P delays, the first 6 and second 7 functional converters, the recorder 8, the adder 9, the sensor 10 load, the comparator 11 and the block 12 correction. The registrar 8 contains three registration channels, each of which consists of, Q and T of the voltage-frequency converter 13 connected in series, the frequency divider 14 and the counter 15.

Correction unit 12 comprises an adder 16, first 17, second 18, third 19, fourth 20 and fifth of 21 keys, element NOT 22, first 23 and second 24 sources of reference voltage, first 25 and second 26 amplifiers, first 27

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and second 28 integrating elements

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The first 29, second 30 and third 31 current-limiting elements.

The device works as follows.

In the start-up mode, all 45 units of the device are working. In the stationary mode of operation of the machine, the flow is recorded using a load sensor 10, a correction unit 12, a functional converter 7, an analog and voltage adder 9, and a registrar register 8.

When the machine is started up, the monitored vibration parameters are sensed by sensors 1 ... 1P, from their outputs the signals go to the information inputs of the keys 2 4 ... 2 n, as well as to the inputs of amplitude detectors 34 ... 3h. In addition, each amplitude detector

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produces storing and storing the maximum value (for the first half period) of the output signal from the corresponding sensor. Thus, the amplitude detectors record the maximum of the aperiodic transient vibration process of the controlled winding rods. The signals from the outputs of the amplitude detectors Z4 ... 3p are fed to the input of the maximum voltage selector 4. For any ratio of input signals at one of the outputs of the selector 4, a permission signal appears to open one of the keys 2 / (... 2G1, which is connected to the output of the sensor with the highest signal recorded by it for the first half period. Signal output from the selector 4 to the second (control) inputs of the keys is made with a time delay set by the corresponding delay elements 5 ... 5h, since the amplitudes of the vibration of the three-phase stator winding rods of the motor caused by the starting currents are shifted symmetrically out of phase by ( 120 °). Therefore, the time of occurrence of the maximum aperiodic vibration of the rods of different phase groups, depending on the moment of switching on the engine, will be shifted relative to each other by T / 6, i.e. 10 / 6- 1.67 ms (the period of the vibration process Since the maximum of the aperiodic vibration is observed in the first half period, the delay time is taken t9oA 5 ms (T / 2). This eliminates the possibility of a false unlocking from the keys 2, ... 2W, which is controlled by the output selector 4 by the presence of the first, but not all the greatest phase maximum but. The time delay allows for the correct switching of keys, so the output of that sensor 1- is connected to the input of the first functional converter 6, the signal from which was allocated as the maximum selector 4 and having a fading aperiodic character with a maximum amplitude in the first half period.

The first functional transducer 6 makes it possible to reproduce the aforementioned non-linear continuous function of the dependence of the developed insulation resource on the vibration amplitude. Accounting for the development of the resource from vibration only in transient mode: pea is achieved

The first functionalization of the converter 6 with the dead zone at small input signals. The output of the first functional converter 6, the magnitude of which is proportional to the rate of output, by the converter 13, the voltage-frequency is converted into a sequence of pulses. Moreover, with an increase in the amplitude of the controlled parameters, i.e. as the output of the resource increases, the output frequency of the converter increases proportionally. The converter should have high linearity and the ability to adjust the output frequency. In order to reduce the counter size of the counter, the pulses of the first converter 13, the voltage-frequency are fed to the counter by the counter 15 (through the first frequency divider 14

Thus, the quantitative filling of the first counter 15 characterizes the production of a resource from the effects of vibration. At the same time, the accuracy of the device is enhanced by switching with a delay of the maximum aperiodic signal, i.e. elimination of an erroneous estimate of the output during phase shift of signals.

The definition of the thermal wear life is as follows. When the machine is started up from the output of the load sensor 10, included in the power supply current source, a voltage proportional to the switching current is applied to the input of the comparator 11. Examples of the load sensor 10, as a current-to-voltage converter, are transreactors or transferors loaded with resistance. Comparator Trigger

11 at the start-up, results in the appearance at the output of the signal correction block 12 proportional to the change in the winding temperature in transient conditions. During start-up, the output signal of the block

12 correction is proportional to the linear temperature rise of the winding above the ambient temperature,

and at the end of the start-up - a general increase in the temperature of the winding due to heating by starting currents. After the start of the start, the signal at the output of unit 12 is proportional to the exponential decrease in temperature from the maximum during the start up to the temperature of the stationary mode. With repeated starts and self-starts, the output signal of the block

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thirty

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12 is proportional to the temperature rise from the intermediate level, corresponding to the cooling of the winding during the time between starts, dc the maximum starting temperature. During steady-state conditions with the return of the comparator 11, the signal from the drive of block 12 is proportional to the operating temperature of the winding. Therefore, the correction unit 12 reproduces the winding cooling cooling model adequate for the real process in various operating modes.

A signal proportional to the temperature in the corresponding operating mode is output from the unit 12 to the second functional converter, reproducing a nonlinear continuous function of the dependence of the isolation resource on temperature. The signal proportional to the output indicator from the output of the second functional converter is supplied to the input of the 13C converter voltage-frequency and is converted into a pulse sequence, which through the frequency divider 14j enters the counter 155, the filling of which characterizes the development of the resource from the thermal effect. Due to the higher value of the output signal of the correction unit 12, in the start-up modes the filling of the counter 153 occurs more intensively than in the stationary mode.

Signals proportional to the indicators of the output of the resource from vibration and temperature, respectively, from the outputs of the first 6 and second 7 functional converters are fed to the first and second inputs of the adder 9, the output of which is proportional to the total output converted by the converter 13 /, the voltage-to-pulse into sequence, which through the divider 14 frequency enters the counter 15 2.

Thus, in the recorder 8, the devices accumulate the components of the resource development from the effects of vibration and temperature, respectively, in the meters 15, and 15, and the total resource development in the counter 15.2.

To determine the output from vibration during subsequent starts, it is necessary to reset the amplitude detectors 3 "... 3" after the end of the start. Moreover, in view of the operational diminution and stiffness of the winding fastening and

an increase in vibration as a criterion for the end of the start cannot be considered to be its decrease. Therefore, the moment of completion of the starting mode is determined by the return of the comparator 11, since the starting current decreases several times to its nominal value. At start-up, the operation of comparator 11 results in the appearance at the second inputs of an amplitude detector 3A., 3P of a signal permitting a selection of the magnitude of the maximum vibration. The return of comparator 11 removes the sample enable signal, and the amplitude detectors go into reset mode.

The operation of the correction unit 12, which reproduces the signal proportional to the change in temperature in various modes of equipment operation, is as follows. Comparator 11, whose setting is proportional to double

At the first input of block 12, the positive potential of the stator current, srabaty-ier, is generated, which causes opening (short-circuiting) .i pBoio 1 /, second 18 and fourth

O.:; yuchey. Inversi - enter the signal

ment rUj 22 leads to the closure and sniffing) of the third 19 and n of the 21 keys. When etrm is charged

 the integrating element 27 through the first current-limiting element 29 from the first source 23 of the supporting voltage. uVn (t), i-exp (-t / TH) with te (0, tn),

(1) where E is the voltage of the first source-1

ka 23 supporting voltage; T - constant heating (cooling

Deni) engine C - capacitor capacity of the first

integrating element 27; R4 is the resistance of the first

limiting element 29. The charging circuit parameters are chosen so that during the start-up time tn the voltage & V n on the element 27 is on the linear branch of the charging characteristic, to the model that the temperature of the winding exceeds the ambient temperature. Through the first amplifier 25, the signal bVn (t) of (1) is applied to the first input of the analog adder 16, to the second input of which, via the fourth key 20, the voltage of the second source 24 of the reference nlprch is applied, proportional to

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tour of the environment. The signal at the output of the adder 16 is equal; Vn (t) bVn (t) + VOK with te (0, tn-) (2) and with proportional to the total winding temperature per start. Since the second switch 18 is open, the voltage on the integrating element 28 repeats the voltage according to formula (2) and the signal at the output of unit 12 is proportional to the total rise in winding temperature during start.

The selection of the parameters of the charge circuit to ensure that uVn (t) is located at the initial (linear) section of the charge characteristic can be made using known ambient temperatures at the installation site and the maximum allowable for this class of insulation. The magnitude of the voltage E, the first source 23 of the reference voltage, is selected on the basis of the motor-specific constant heating at the maximum starting time for the mechanism. The heating characteristic is approximated directly. The resulting modeling error, for example, with the start-up duration tn 25 s and Tjj-290 s is 5%, and with c it is 2%, i.e. is insignificant for engines of various types, dimensions and power.

At the end of the start-up and return of the comparator 11, the first 17, the second 18 and the fourth 20 keys are closed, the third 19 and fifth fifth keys are opened. In this case, the element 27 is discharged through the key 19 and the element 30 with a constant cooling time equal to the constant heating & V (t) kVn / t LP.hr (-1: / Tn) with, (3)

 where Ra;

R. - the resistance of the second current-limiting element 30, equal to the resistance of the first current-limiting element 29.

The voltage on the second integrating element 28 that has reached Vp / t-tw is changed to Vg), corresponding to the stationary temperature and present at the second input of block 12. At the output of block 12, the signal has the form:

V (t) Ve + (Vn / tein-V0). exp (-t / TH) with, (4)

where is ti

Cf - capacitor of the second integrating element 28;

Rj is the resistance of the third current-limiting element 31.

Thus, after the end of the start, the signal at the output of the correction unit 12 is proportional to the exponential decrease in temperature from the maximum during the start-up to steady-state temperatures. When operating in stationary mode, the signal from the output of unit 12 is proportional to the temperature of the winding due to the simulation of working overloads using an inertial link — element 31 and element 28 of the constant motion heating time. The neglect of the ambient temperature in this case is permissible, since the heat transfer of the engine rotating at the nominal speed is more intense than at the start.

When restarting or in self-starting mode, the state of the keys is similar to the state for starting mode. However, the voltage & Vno on the first integrating element 27 when the time between starts is less than 3 -Tn is different from zero, because the capacitor element 27 does not have time to discharge according to the formula (3). Therefore, the voltage on you.

1569856

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Mule Invention

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Claims (3)

I. Device for registering the resource of machines, containing sensors, the outputs of which are connected to the information inputs of keys and amplitude detectors, the outputs of which are connected to the inputs of the maximum voltage selector, the control inputs of the amplitude detectors are combined, the outputs of the keys are combined and connected via the first functional converter to the first A recorder input, characterized in that, in order to increase the accuracy and informational content of the device by taking into account the heating-cooling processes of the machine windings, load sensor, comparator, adder, second functional converter, correction unit and delay elements whose inputs are connected to the outputs of the maximum voltage selector, and output and.- are connected to the control inputs of keys, the output of the first functional converter is connected with the first input of the adder whose output is connected to the second input of the recorder, during block 12 when restarting pro-ed, the output of the load sensor is connected in proportion to the temperature rise from an intermediate value corresponding to the cooling of the winding during the time between starts K, () E, - (E, -bVlfe) exp (-t / T |,) + VOK with t Ј (0, tn). (5) In this way, the correction unit 12 makes it possible to create with a high degree of accuracy an engine winding-cooling model adequate to the actual phy & th process in various operating modes: starting, self-starting and intermittent, as well as stationary with the possibility of short-term overloads. In this case, the main engine parameters affecting heat are taken into account. The use of the proposed device makes it possible to increase the accuracy of determining the technical condition of the mask, which makes it possible to predict the work and the need for repairing equipment, thereby providing the opportunity to reduce operating costs. The operation of the technical connection allows to increase the real service life of the equipment and increase the reliability of the technological circuits. five 0 five 0 five the cut comparator with the first input of the correction unit and the control inputs of the amplitude detectors, the input of the comparator is combined with the second input of the correction unit, the output of which is connected through the second functional converter to the second input of the adder and to the third input of the recorder. 2. The device according to claim 1, characterized in that the registrar contains three registration channels, each of which consists of series-connected voltage-frequency converter, frequency divider and counter, the inputs of the first, second and third voltage converters Neither the frequency are the first, second, and third inputs of the recorder, respectively. 3. The device according to claim 1, characterized in that the correction unit contains keys, an element NOT, reference sources, amplifiers, an adder, integrating and current-limiting elements, the output of the first source of reference voltage is connected to the information input of the first key, the output which is connected in series through the first tokog. & rf c, d Sh Fig 2 g / g