JPS62218883A - Apparatus for monitoring operation state of electromotor - Google Patents

Abstract

PURPOSE:To discover the abnormality of an electromotor and the system to be driven by said electromotor before the electromotor is stopped by trouble, in monitoring the operation state of the electromotor, by setting tolerant upper and lower limit values and a pulsating value, etc. on the basis of the set current flowing to the electromotor as the time of a steady operation. CONSTITUTION:The current flowing to an electromotor 3 revolving corresponding to load is detected through a current transformer 2 to be converted to voltage by a steady current setting circuit 5. The sensitivity of the circuit 5 is adjusted so that the display device 14 of a steady state display circuit 6 is operated by the definite converted voltage outputted from the circuit 5 by the steady operation of the electromotor 3. On the basis of the converted voltage from the circuit 5 at this time, an upper limit value excess display circuit 7, a lower limit value lowering display circuit 8 and a pulsation display circuit 9 are controlled and it is monitored whether the operation state corresponding to the load of the electromotor is within a tolerant range. Therefore, the abnormality of the electromotor and load can be discovered before the electromotor is stopped by a trouble by monitoring the display devices 14, 19, 25, 33 of the circuits 6-9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a device for constantly monitoring the operating state of an electric motor;
The present invention relates to a device that detects changes in current value and current pulsations that occur during abnormal operating conditions of a motor to indicate abnormal operating conditions of the motor.

Conventional technology Conventional motor failure detection is performed using motor breaker-93EIJ.
Relays (protective relays for open phase, short circuits, reverse phase, etc.), etc., which detect an increase in the current flowing through the motor and cut off the circuit to stop the motor and stop burnout.
Install a motor C two-vibration sensor to detect abnormal vibrations such as bearing abnormality or shaft misalignment and display the abnormality, or use a sound collector to measure the sound of the electric motor notification, and detect when the bearing is abnormal. A method was used to detect abnormal sounds and display the abnormal sounds.

Problems to be Solved by the Invention The method of detecting the current of a motor is when a large current flows due to a short circuit or an open phase (C); It is detected after the motor has malfunctioned after it has started operating, so the motor can be repaired or replaced (C); It takes time, and equipment driven by the electric motor must be stopped during that time.
The method of attaching a vibration sensor or sound collector to the motor to detect abnormalities in the bearings, etc. can detect abnormalities before the motor stops, but this method causes various inconveniences. Detection of abnormalities such as abnormalities and axis misalignment is limited, and abnormalities such as overcurrent, overload, overheating, load fluctuation, poor conduction, etc. cannot be detected.

Means for Solving the Problem The present invention provides for
Using the flowing current as a reference, set the upper and lower limits of the allowable fluctuation range and pulsation around that reference.Motor C: When the flowing current exceeds these set values (2 abnormalities are displayed) Before detecting an abnormality in the electric motor and equipment driven by the motor and causing a failure stop C: To discover an abnormality ≦
This is what happened.

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention.
In the figure, Hlc is the electric motor 3, C: the conductor that supplies power, 2 is the current transformer provided with the conductor 1bC, 4a and 4b are the output signal terminals of the current transformer 2, and 5 is the steady current setting circuit. The output signal ``■'' of the current transformer 2 is input, and an output signal V proportional to the input voltage is outputted.

B is a steady state display circuit, and the steady state display circuit B is a sensitivity adjuster 11. an amplifier 12 made of a semiconductor or the like that amplifies the output signal of the sensitivity adjuster 11 by a predetermined magnitude C2; a level made of a semiconductor or the like that becomes sensitive when the output signal of the amplifier 12 reaches a predetermined level; The level detector 13 includes a detector 13 and a display 14 including a relay driven by the level detector 13. T is an upper limit value excess display circuit, and the upper limit value excess display circuit 7 is a sensitivity regulator that adjusts the operating voltage value of the upper limit value excess display circuit 7 when the output old number V of the steady state magnetic current setting circuit 5 increases. 15, and an amplifier 1B made of semiconductor or the like that amplifies the output signal of the sensitivity adjuster 15 to a predetermined size.
It is composed of a level detector 11 made of a semiconductor or the like that senses when the output signal of the amplifier 1B reaches a predetermined level C; a relay 18 driven by the level detector 17; and a display 19. ing. 8 is a lower limit value drop display circuit;
The lower limit value drop display circuit 8 includes a sensitivity adjuster 21 that sets a voltage value at which the lower limit value drop display circuit 8 operates when the output signal V decreases, and a sensitivity adjuster 21 that adjusts the output signal of the sensitivity adjuster 21 to a predetermined magnitude. C: Driven by an amplifier 22 made of a semiconductor or the like to amplify the signal, a level detector 23 made of a semiconductor or the like that senses when the output signal of the amplifier 22 drops by a predetermined level C2, and the level detector 23. relay 24 and display 2
5 It's getting better. Reference numeral 8 denotes a pulsation display circuit, and the pulsation display circuit 9 includes a rectifier 21 for rectifying the output signal V of the steady-state current setting circuit 5 and substituting it with two direct currents, a filter 28 for increasing the change in the DC signal, and a separate circuit. Sensitivity adjuster 2 that sets the operating value of the pulsation display circuit when the pulsation signal exceeds a certain value
9, an amplifier 30 that amplifies the output signal of the sensitivity adjuster 29 by a predetermined amount, a level detector 31 and a level detector 3 that are sensitive when the output signal of the amplifier 30 reaches a predetermined level.
The relay 32 and the display 33c are configured to be driven at one time. The steady state table circuit 6 is adjusted by the C dual-sensitivity regulator 11 so that the C: indicator 14 operates when the output signal V of the steady current setting circuit 5 reaches a constant voltage, for example, 1 volt.

When monitoring the operating state of the electric motor 3, the electric motor 3 is first operated by applying a steady load such as a blower or a pump. At this time, a current I corresponding to the load flows through the motor 31, and the output signal terminals 4a + 4b s2 of the current transformer 2 are
An output signal I' proportional to this current it appears, and this signal 2' is applied to a steady current setting circuit 5 comprising a variable resistor or the like. Next, the sensitivity of the steady-state current setting circuit 5 is gradually increased, and it is fixed when the indicator 14 of the steady-state display circuit 6 shows the value. The output signal V at this time is 1 volt. This operation sets the current value to 100% in the normal operating state of the motor, where the current that varies depending on the motor capacity, load condition, etc., and the upper and lower limit values are set based on this current value. If you want to set the tolerance range, for example, lo%c, adjust the sensitivity adjuster 15 of the upper limit excess display circuit 7 so that it operates when the output signal of the steady flow setting circuit 5 is 1.1 volts or less. In addition, the lower limit value reduction table circuit 8
The sensitivity regulator 21 is adjusted so that the output signal V operates at 0.9 volts. When the motor 3 is operated with these settings, the load current! is 1 from the current during steady operation.
If the load current exceeds 0% or more, the upper limit excess display circuit 7 operates and the display 19 indicates that the load current is outside the allowable range.Also, if the load current exceeds 10% or more, the lower limit The value decrease display circuit 8 operates to display and notify on the display 25.

The permissible change range of the load current of the motor 3 is determined by the sensitivity adjuster 15.
Since the electric current can be set freely in and 21, the current can be set to a value sufficiently smaller than the current at which the distribution line circuit breaker thermal relay operates.

In addition, if the bearings of the electric motor are worn out, the axis is misaligned, the transmission belt of the equipment is loosened, the fan blades are bent, air is mixed in the pump, etc.
It produces pulsations like this. This pulsating signal is rectified by a rectifier 27 in the pulsating display circuit 9 and converted into a DC signal, and then passed through a filter to obtain a pulsating waveform as shown in FIG. If the degree of this pulsation exceeds the limit set in advance by the sensitivity adjuster 29, an operation display will be displayed to notify you of an abnormality.

The current flowing through the motor 3 flows in proportion to the output torque of the motor (2), and when the mechanical output torque of the motor changes, the current flowing through the motor 1 also changes. Factors that increase the current of the motor include insulation deterioration, bearing wear, seizure, and abnormalities in equipment driven by electric motors.In addition, factors that cause the electric current to decrease include, for example, when the load on the electric motor becomes lighter, (belt slipping, cutting, pump falling into water, water supply pipe clogging), blower, etc. If the filter becomes clogged and the air volume decreases, workpiece detachment from machine tools, compressor, etc. Possible causes include oil leakage and idling.

t'IP: , The cause of the pulsating current in the motor C is damage to the motor's bearings, misalignment of the shaft, loosening of the belt for power transmission of the load equipment, warping of the fan blades, etc.C; Occur.

Effects of the Invention As explained above, the present invention adjusts the current during steady operation using the steady current setting circuit 5 even if the capacity and load of the motor change, and uses this as a reference (100 CH) to set the current to the reference C; Since the load current of the motor is constantly monitored by setting the upper limit value, lower limit value, and pulsation signal value of the allowable fluctuation range, it is possible not only to prevent the failure of the motor itself, but also to reduce the It is also possible to monitor malfunctions in equipment and equipment, and detect abnormalities before the motors and the equipment operated by the motors malfunction and stop. Therefore, one measure can be taken before an accident occurs, and the above-mentioned drawbacks of the conventional technology are completely eliminated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
Figure (a) is a waveform diagram of the pulsating current flowing through the motor, and Figure (b1) is a pulsating waveform diagram obtained by averaging the pulsating current waveform with a filter. , 3... electric motor,
5... Steady current setting circuit, B... Steady state display circuit, I... Upper limit value excess display circuit, 8... Lower limit value decrease display circuit, 9... Pulsation display circuit.

Claims (1)

[Claims] a steady-state current setting circuit that receives an electric signal proportional to the input current of the motor and adjusts the input signal to a constant value; a steady-state display circuit that is connected to the output side of the steady-state current setting circuit and operates based on the output signal; an upper limit value excess display circuit and a lower limit value decrease display circuit connected to the output side of the steady current setting circuit and activated when the output signal changes above or below a predetermined set value; and a circuit that is proportional to the input current of the motor. 1. A motor operating state monitoring device comprising: a pulsation display circuit which receives an input electrical signal, detects pulsation of the input signal, and operates when the pulsation exceeds a set value.