SU1638669A1 - Device for checking electrical apparatus coils - Google Patents

Abstract

The invention relates to instrumentation technology and can be used to detect short circuits in the coils of electrical apparatus. The purpose of the invention is to increase the reliability of control - achieved by detecting hidden closures when the controlled coil is heated. The device for controlling the coil 1 contains a capacitor 2, an inductance 3, a magnetic circuit 4, a generator 5 of sinusoidal voltage, keys 6, 13, a heating source 7, an amplifier-limiter 8, a control unit 9, a limiting voltage source 10, a reference source 11 voltage, comparator 12. By introducing keys 6, 13, source 7 of heating voltage, control unit 9, the device provides control of coil 1 under current heating conditions, which reveal hidden defects and increase the reliability of control. 2 Il. about

Description

The invention relates to instrumentation technology and can be used to detect short circuits in the coils of electrical apparatus.

The purpose of the invention is to increase the reliability of control by detecting hidden closures by heating the controlled coil.

FIG. 1 is a diagram of the device} in FIG. 2 - timing charts of the device.

The device for controlling the coil (Fig. 1) contains a capacitor 2, inductance 3, magnetic core 4, generator 5 of sinusoidal voltage, first switch 6, source 7 of heating voltage, limiting amplifier 8, control unit 9, source 10 of limiting voltage, reference source 11, comparator 12, second switch 13.

The control unit 9 comprises a pulse shaper 14, 15, 16.

Limiter 8 comprises amplifier 17, rectifier 18, limiter 19, amplifier 20. FIG. 1 also denotes input 21, input 22 and device output 23, point

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24 connecting capacitor 2 and inductance 3.

The output of the sinusoidal voltage generator 5 is connected via a capacitor 2 to a first inductance terminal 3 connected by a second terminal to a common bus of the device and placed on the magnetic core that houses the controlled coil 1. The first input of the limiter amplifier 8 is connected to the output of the voltage source 10 restrictions, output — to the first input of the comparator 12, connected by a second input to the output of the source 11 of the reference voltage, output — to the output 23 of the device. The input of the control unit 9 is connected to the first input 21 of the device, the first output is connected to the control input of the first switch 6 connected by a signal input through the heating voltage source 7 to the second input 22 of the device, the output is connected to the first terminal to connect the monitored coil 1, A second terminal for connecting which is connected to a common bus device. The second output of the control unit 9 is connected to the control input of the second switch 13, connected by a signal input to the first inductance terminal 3, and to the output to the second input of the limiting amplifier 8.

The device works as follows.

In the initial state, the keys 6 and 13

are open, and the source 7 of the heating voltage and the common point of the capacitor 2 and inductance 3 are disconnected, respectively, from the coil 1 and from the input of the amplifier-limiter 8.

Capacitor 2 and inductance 3 form a resonant circuit that is pre-tuned to resonance with the frequency of generator 1. Inductance 3 and a controlled coil 1 are placed on a common magnetic core 4. Therefore, they form a transformer, since have a magnetic transformer coupling and the parameters of the transformer secondary circuit (coil 1) affect the parameters of the primary transformer circuit, in particular, the voltage coming from common point 24 to the signal input of key 13. When coil 1 closes, sinusoidal voltage is at 24 decreases.

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The trigger signal received at the device input 21 triggers the pulse shaper 14 in the control block 9 (Fig. 2) and sends a pulse to the control input of the key 6, which switches the key 6 to the conducting state, and the source 7 through the key 6 connected to the time D of the pulse of the former 14 to the controlled coil 1, which is heated by the current of the source 7 during the time & t.

On the falling edge of the pulse of the shaper 14, the key 6 is locked, the heating of the coil 1 is stopped and the shaper 15 is started (FIG. 2), which delays the start of the shaper 16 for a time & t2% Delay D. t is necessary for the transient The process associated with the opening of the switch 6 in the inductance circuit 3 and the coil 1 ended and the voltage surges at point 24 formed at the moment of opening did not affect the result of the control. The time A.t is chosen sufficient to complete the transition process, but it is not enough to cool the coil 1, therefore the defects revealed during heating remain.

After the time A.t2 passes over the falling edge of the imaging unit 15, the imaging unit 16 is started, which for the time D.to (figure 2) unlocks the key 13, and the signal from point 24 enters through the key 13 to the input of the amplifier-limiter 8, where it amplifies rectified, limited to remove overvoltages, and fed to the input of comparator 12.

In the event that, when coil 1 is heated, hidden defects appear in it, for example, closure of coils, the voltage at point 24 and, accordingly, at the output of amplifier-limiter 8 is constant and less than in case of suitable coil 1. Voltage. the input of the comparator 12 is less than the reference voltage of the source 11, and the comparator 12 outputs to the output 23 a signal indicating a failure of the coil 1.

Limiting amplifier 8 provides a comparison of the voltage at point 24 in the presence of the tested coil 1 on the magnetic core 4 with the same voltage obtained. In the absence of the tested coil 1,

there is a difference between these voltages greater than a certain value and the amplification of the difference signal.

The principle of the amplifier-limiter 8 consists of four successive operations on the input voltage. The first operation is amplification by an amplifier 17 with an offset of the level of the operational amplifier. In this case, a bipolar alternating voltage is obtained with a sinusoidal positive and a bounded negative negative half-wave. The second step is the straightening by the rectifier 18 with the fixation of the lower level, and a sequence of positive sinusoidal pulses is obtained, the bases of which are fixed at the first positive level. The third operation is the limiting by the limiter of 16 pulses from below at the second positive level, exceeding the first one. The fourth step is a gain with a second gain. i

The need to offset the zero of the first amplifier 17 is due to the fact that to eliminate the influence of interference, the input voltage level in a specific implementation must be 18, to ensure the operation of subsequent stages, the gain of the specified difference in input voltages must be K ,, AO, but without additional measures to receive from the used integrated operational amplifier K553UD2, whose output voltage amplitude does not exceed 10V, the gain from K1 (. 40, because 10V / 1V 10. Information about the closure of the coils is carried as positive and the negative amplitudes of the input voltage of the amplifier are 17, therefore it is sufficient to amplify only, for example, positive amplitudes by applying a signal to one input of the operational voltage amplifier, and a certain positive voltage to the other input. applied to the inverting input in the absence of a signal, causes a negative offset, the output voltage, and in the presence of a signal at the non-inverting input causes a lower limit

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output voltage. The bias voltage is chosen so that at the required gain, the form

the positive half-waves of the output voltage of the amplifier 17 remain sinusoidal, the negative half-waves, however, are limited. The necessity of rectifying by rectifier 18 after amplification is caused by the necessity of supplying to the limiter 14 a voltage of only positive polarity. The negative half-waves of the output voltage of the rectifier are fixed at the first positive level to facilitate the operation of the limiter 19.

In limiter 19, the limiter voltage is chosen to be equal to the level of the positive signal voltage amplitudes corresponding to the presence of closed turns. Depending on their number, which, according to the conditions of control of the coils, is required to be detected, this voltage, determined by source 10, can be changed by the user. With such a choice of the second positive level, the output signal of the limiter 19 is positive sinusoidal pulses, when there are no closed turns, or almost constant voltage, when they exist.

The output voltage of the limiter 19 is produced to provide the operating mode of the comparator 12, to the input of which in the first case an alternating voltage is supplied and in the second a constant voltage.

Claims (1)

0 Thus, the device provides control of coil 1 under conditions of pre-impulse heating, which ensures detection of latent defects and increases the reliability of control of interturn circuits. Invention Formula five A device for controlling electric device coils, containing a sinusoidal voltage generator connected by an output through a capacitor to a first inductance terminal connected by a second output to a common device bus and placed on a magnetic core that holds a controlled coil, an amplifier-limiter connected to the source input of a voltage source restrictions on the wife’s exit the first input of the comparator connected by the second input to the output of the voltage source, and the output to the output of the device, so that, in order to increase the reliability of the control, two terminals for connecting the controlled coil, control unit , two keys, a heating voltage source, the input of the control unit being the first input of the device, the first output of the control unit being connected to the control the input of the first switch connected by the signal input through the heating voltage source to the second input of the device, and the output to the first terminal for connecting the controlled coil, the second terminal for connecting of which is connected to the common bus of the device, the second output of the control unit is connected to the control input of the second key , connected by a signal input to the first inductance output, output - to the second input of the amplifier-limiter. Compiled by V.Dvorkin Editor M.Tsitkina Tehred A. Kravchuk Proofreader S.Cherni Order 926 Circulation 428 VNIIPI Goeudarstvechnogo Committee on Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, 4/5 Raushsk Nab. I Subscription