KR100815743B1 - Apparatus for judging faults of second resistor in windinginduction motor - Google Patents

Abstract

The present invention relates to a wound induction motor, and the secondary resistor failure diagnosis apparatus of the wound induction motor of the present invention detects a current of the secondary resistor of the induction motor, and when the detected current corresponds to a fault current, It is configured to cut off the supply line for supplying power to the induction motor, and according to the present invention, by detecting and displaying a failure for the secondary resistor of the winding type flow motor, it is possible to early action in the event of a failure related products The secondary resistor failure diagnosis apparatus of the wound induction motor to prevent burnout of the present invention.

Wire-wound, induction motors, resistors, faults, diagnostics

Description

Second Resistor Fault Diagnosis Device for Wound Induction Motors {APPARATUS FOR JUDGING FAULTS OF SECOND RESISTOR IN WINDING INDUCTION MOTOR}

1 is a secondary resistance control circuit diagram of a conventional winding type induction motor.

2 is a block diagram of a secondary resistor failure diagnosis apparatus of a wound induction motor according to the present invention.

3 is a detailed circuit diagram of the current detector 10, the current amplifier 20, and the presence / absence detection unit 30 of FIG. 2.
4 is a detailed circuit diagram of the current comparator 40 to the switching controller 70 of FIG.

5 is an operation flowchart of a secondary resistor failure diagnosis apparatus of a wound induction motor according to the present invention.

Explanation of symbols on the main parts of the drawings

1: Magnet Concrete 1A: Rotor

2: induction motor 3: slip ring

4: secondary resistor 5: disconnection

6,7,8: Magnet contact for secondary short circuit

9 stator 10 current detection unit

20: amplification unit 30: current presence detection unit

40: current comparison unit 50: fault detection unit

60: failure determination unit 70: switching control unit

80: fault display unit

The present invention relates to a wound induction motor, and more particularly, to detect and display a failure of a secondary resistor of a wound flow motor, thereby enabling early action in the event of a failure to prevent burnout of related products. A secondary resistor failure diagnosis apparatus.

In general, a winding type induction motor is suitable for a load having a large and constant starting torque, such as a overhead crane, and controlling speed.

FIG. 1 is a secondary resistance control circuit diagram of a conventional winding type induction motor. Referring to FIG. 1, a secondary resistance control circuit of a conventional winding type induction motor will be described.

As shown in FIG. 1, when the primary magnet concrete 1 is inserted, the slip ring 3 installed on the rotor 1A shaft of the induction motor 2 while the rotor rotates by a rotor field generated in the stator 9. The secondary resistors R1, R2, and R3 are connected through the control panel, and the secondary resistance values are varied to control torque and speed. By shorting or opening, the resistance value is varied.

To vary the secondary resistor, many taps are needed to divide the resistance values, such as the secondary side magnet contacts 6, 7, and 8 of FIG. 1 into quadrants or fifths as needed for precise control of three or more portions. By dissipating the current from the resistor to heat, the disconnection caused by the deterioration of the resistor and the wear and burnout of the magnet-conductor tip for short-circuit, which occurs in many split taps, are frequently generated.

Although such secondary resistor disconnection causes secondary current unbalance and adversely affects the starting operation and service life of the motor, the conventional apparatus cannot detect the secondary disconnection failure and continues to use it in a faulty state. There was a problem that the failure spreads, such as causing damage.

The reason for not detecting the disconnection failure in the conventional control process will be described in detail as follows.

Assuming that the disconnection is made between the U phase resistors R2 and R3 of the disconnection part 5 of FIG. 1, the primary magnet compact 1 of FIG. And rotate. In this state, the resistance value of the secondary resistor is that the resistance of the V and W phases normally applies voltage to the entire resistance, but is disconnected to the U phase so that no voltage is applied. As a result, the secondary side of the motor is supplied with a three-phase unbalanced current to start abnormal start. After 0.8 seconds to 1 second for the starting current regulation, a short-circuit magnet contact 8 is inputted, and the resistance of each phase is total resistance (R1 +). R2 + R3) is changed to the value of the resistor (R1 + R2) minus the resistance (R3).

In this state, since the resistance value of each phase becomes uniform, the motor also performs normal starting operation. After that, as described above, after a certain time, the magnet contact 7 for short circuit is sequentially inputted, and the virtual resistance value takes only the resistance R1 value, and when the last contact 6 is input, the resistance value is zero at the highest speed. The secondary resistance control method is used to output power.

Then, the reason why the conventional failure was not detected will be explained. For the sake of understanding, the stator 9 side of the winding type induction motor 2 of FIG. 1 is called the primary side, and the rotor 1A side is the secondary side. In this case, in the conventional motor failure detection method, an overcurrent relay is installed on the primary side of the motor, and when a failure occurs, the overcurrent is detected and the control system is tripped to give a stop signal. At this time, the overcurrent relay sets the time limit from 2 seconds to 3 seconds before detecting the over current value and giving the trip command. The reason is that over current of 200% ~ 300% of the rated current until the motor is stopped in operation Because it flows. This means that the tripping should not occur while the starting current is flowing, but it will trip when the failure occurs. As a result, the motor starting time is 2 seconds to 3 seconds, whereas the short-circuit magnet cone 8 for varying the secondary resistor resistance value is used. The resistor was disconnected within 1 second after starting the primary, eliminating the fault condition of the resistor and returning to normal.

The overcurrent relay must be kept for at least 2 to 3 seconds to trip, but in the conventional control system, the current cannot be tripped because it is less than 1 second. The control method as described above has a problem in that the instantaneous failure is continuously accumulated and repeated, thereby decreasing the lifespan and energy efficiency of the electronic device and spreading to a large equipment failure.

The present invention has been made to solve the above problems, and therefore, the object of the present invention is to detect and display the failure of the secondary resistor of the winding type motor, it is possible to premature action in the event of a failure of the associated product It is to provide a secondary resistor failure diagnosis device of the wound induction motor to prevent the damage.

As a technical means for achieving the above object of the present invention, the secondary resistor failure diagnosis device of the wound type induction motor of the present invention detects the current of the secondary resistor of the induction motor and this detection current corresponds to the fault current. In this case, it is characterized in that it is configured to cut off the supply line for supplying power to the induction motor.

Hereinafter, a secondary resistor failure diagnosis apparatus for a wound induction motor according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings referred to in the present invention, components having substantially the same configuration and function will use the same reference numerals.

FIG. 2 is a block diagram of a secondary resistor failure diagnosis device of a wound induction motor according to the present invention. Referring to FIG. 2, the secondary resistor failure diagnosis device of a wound induction motor according to the present invention is a wound induction motor. A current detector 10 for detecting a current flowing through the secondary resistor of (2), an amplifier 20 for amplifying the detected current of the current detector 10 with a set gain, and from the amplifier 20 When a fault is detected by comparing a detection voltage corresponding to the detection current with a set voltage and outputting a level signal according to the comparison result, a fault is detected according to the level signal of the current comparing unit 40. A failure detection unit 50 providing one pulse, a failure determination unit 60 which counts the pulses of the failure detection unit 50 and compares the counted pulse value with a set pulse value to provide a level signal, and the failure determination unit. ON or according to the level signal of the unit 60 A switching controller 70 for providing a pre-switching signal and a power switch 1 installed at a power supply terminal of the induction motor 2 to switch the power supply according to the switching signal of the switching controller 70. do.

In addition, the secondary resistor failure diagnosis device of the wound induction motor is a current presence detection unit 30 to determine the presence or absence of the detection current of the current detection unit 10 to provide a switching signal according to the determination result, and the presence of the current The first switch SW1 for switching the output of the amplifier 20 according to the switching signal of the detector 30 and the fault display unit 80 for counting the output pulses of the fault detector 50 to display the number of failures. Configure additionally.

3 is a detailed circuit diagram of the current detector 10, the current amplifier 20, and the presence / absence detection unit 30 of FIG. 2.
Referring to FIG. 3, the current detection unit 10 has a U phase and a V in front of the secondary resistor of the secondary side of the induction motor 2 in order to detect a current flowing in the secondary resistor of the wound induction motor 2. Current transformers 11 (CTU, CTV, CTW) respectively installed in phases and W phases, and three-phase full-wave rectifier diodes D12 to D17 for full-wave rectification of the AC current (or voltage) detected by the current transformer 11. Configure.

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The amplifier 20 includes an operational amplifier DP21 for inverting and amplifying the current detected by the current detector 10 and bias resistors R21 to R24 of the operational amplifier DP21. In this case, the first switch SW1 may be connected to the output terminal of the amplifier 20, or may be connected in parallel to the feedback resistors R22 and R23 that determine the inverted amplification factor, as shown in FIG. have.

The current presence detector 30 connects an inverting (-) terminal to the current output terminal of the current detector 10, connects a non-inverting (+) terminal to a set voltage corresponding to a preset reference current, and inverts this. Comparator DP31 for comparing the voltage corresponding to the current through the terminal and the set voltage through the non-inverting terminal and switching according to the comparison result signal of the comparator DP31 to provide a switching signal to the first switch SW1. The transistor SW31 is used.
4 is a detailed circuit diagram of the current comparator 40 to the switching controller 70 of FIG.

Referring to FIG. 4, the current comparator 40 includes a comparator DP41 for comparing a voltage corresponding to the output current of the amplifier 20 and a voltage set value corresponding to the reference current.

The fault detector 50 may include a second switch SW2 for switching according to the level signal of the current comparator 40 and a charge / discharge circuit for generating pulses through charging and discharging the signal through the second switch ( R62, R63, C61, a counter 51 for counting each time the pulse signal is input by the charge / discharge circuit, and continuously maintaining a high level to a plurality of output terminals Q1 to Q8; and a plurality of counters 51 And a dip switch 52 for selecting one of the output stages.

The switching control unit 70 switches the contacts 71 or 72 according to the level signal of the fault determination unit 60 and the contact on or off signal to the first switch SW1 in association with the switching operation of the switch. And a relay 73 for providing a light emitting diode 74 indicating a failure in association with the switching operation of the switch.

5 is an operation flowchart of a secondary resistor failure diagnosis apparatus of a wound induction motor according to the present invention.

Operation according to the device of the present invention configured as described above will be described in detail below based on the accompanying drawings.

2 to 5, first, the current detector 10 detects a current flowing in the secondary resistor of the wound induction motor 2. Referring to FIG. 3, the secondary side 2 of the induction motor 2 is detected. The current is detected by the current transformer 11 (CTU, CTV, CTW) of the current detector 10 provided in each of the U, V, and W phases of the front end of the differential resistor (S41), and the detected current is minute. Since it is a signal, the amplifier 20 of the next stage is amplified by the set gain and input to the current comparator 40.

On the other hand, the current presence detection unit 30 determines the presence or absence of the detection current of the current detection unit 10, if there is a detection current and the detected voltage corresponding to this detection current is higher than the set voltage (voltage determined by R35), the comparator ( Transistor SW31 is turned on to provide a switch-on signal as DP41 outputs a high level (S42). On the other hand, if there is no detection current, comparator DP41 is low when the detection voltage is lower than the set voltage. As the level is output, the transistor SW31 is turned off, thereby providing a switch-off signal (S43). The switching on or off signal corresponding to the determination result is provided to the first switch SW1. The first switch SW1 is amplified according to the switching on signal or the off signal of the current presence detector 30. The output of the unit 20 is switched.

In more detail, when the first switch SW1 is connected to the output terminal of the amplifier 20, the amplifier 20 is turned on when the first switch SW1 is turned on when there is a detection current. Is output to the current comparator 40, on the other hand, when there is no detection current, the output of the amplifier 20 is cut off as the first switch SW1 is turned off. When the first switch SW1 is connected in parallel to the feedback resistors R22 and R23 for determining the amplification ratio of the amplifier 20, the operational amplifier DP21 of the amplifier 20 is connected. Since the amplification ratio is "(R22 * R23) / (R21) * input voltage", when there is a detection current, the amplification ratio of the amplifying unit 20 is set to "(R22 * R23) when the first switch SW1 is turned on. / (R21) * input voltage "and the detection voltage is amplified and provided to the current comparator 40, on the other hand, when there is no detection current, the amplification section 20 as the first switch (SW1) is turned off ), The amplification factor becomes "(0) / (R21) * input voltage", and therefore there is no output.

When there is a detection current as described above, the current comparator 40 compares the detection voltage corresponding to the detection current from the amplifier 20 and the set voltage (voltage by R51) again in the comparator DP41. In comparison (S44), the level signal according to the comparison result is output to the failure detection unit 50, and the failure detection unit 50 detects a failure in accordance with the level signal of the current comparator 40 and detects a failure by one pulse. It provides to the failure determination unit 60.

The second switch SW2 composed of the transistors of the fault detection unit 50 switches according to the level signal of the current comparator 40, that is, it is on when it is high level (fault) and is low level (normal). If it is off (S46). Charge and discharge of the signal through the second switch (SW2) in the charge and discharge circuit (R62, R63, C61) to generate a pulse (S47), if this state lasts for 1 second, 120 A pulse is generated. This pulse is input to the counter 51, and the counter 51 counts each time the pulse is pressed. The counter 51 sequentially outputs the high level to the plurality of output terminals Q1 to Q8. For example, if it is configured as 4 pulse count, Q1 output is high when 4 pulses are input, Q2 output is high when 8 pulses are input, and Q3 output is high when 16 pulses are input. The Q4 output is high when the four pulses are input, and the Q5 output is the high level when the 64 pulses are input.

This conversion of 120 correct clock pulses per second into a digital pulse signal that can be clearly recognized is to ensure failure recognition and to enable fault indication (display).

In the comparator U64603 of the fault determination unit 60, the pulse of the fault detection unit 50 is counted, and the counted pulse value is compared with the set pulse value 61 (S49). To provide.

The switching control unit 70 provides an on or off switching signal according to the level signal of the fault determination unit 60 (S50), the power switch 1 is installed in the power supply terminal of the induction motor (2) In addition, the power supply is switched according to the switching signal of the switching controller 70. For example, referring to FIG. 4, the switches 71 and 72 of the switching controller 70, that is, the diode 71 and The transistor 72 is sequentially conducted in accordance with the level signal of the fault determination unit 60, and accordingly, a relay 73 connected to the collector terminal of the transistor 72 is activated to contact the power switch 1 with a contact signal. To provide. The light emitting diode 74 connected in parallel with the relay 73 is also lit to indicate a failure.

The power switch 1 is configured as a point b (normally closed) of the relay 73 of the switching control unit 70, and is opened when the relay 73 is magnetized (S51), and eventually power is supplied when a failure is detected. To block. The failure display unit 80 counts the output pulses of the failure detection unit 50 and displays the number of failures.

According to the present invention as described above, by detecting and displaying a failure for the secondary resistor of the winding-type flow motor, there is a special effect to prevent the burnout of the related products can be early action when a failure occurs.

In addition, other effects of the present invention can be early action when a failure occurs, it is possible to prevent the burnout of the related products, to prevent the reduction of the efficiency of the induction motor, and to prevent energy waste.

The above description is only a description of one embodiment of the present invention, the present invention is capable of various changes and modifications within the scope of the configuration.

Claims (4)

A current detector 10 which detects a current flowing in the secondary resistor of the wound induction motor 2; An amplifier 20 which amplifies the detected current of the current detector 10 with a set gain; A current comparator 40 for comparing the detection voltage corresponding to the detection current from the amplifier 20 with a set voltage and outputting a level signal according to the comparison result; A failure detection unit 50 for detecting a failure according to the level signal of the current comparing unit 40 and providing one pulse at the time of failure detection; A fault determination unit 60 which counts the pulses of the fault detection unit 50 and compares the counted pulse values with a set pulse value to provide a level signal; A switching controller 70 which provides an on or off switching signal according to the level signal of the fault determination unit 60; A power switch (1) installed at a power supply terminal of the induction motor (2) to switch the power supply according to a switching signal of the switching controller (70); A current presence detection unit 30 which determines whether there is a detection current of the current detection unit 10 and provides a switching signal according to the determination result; A first switch (SW1) for switching the output of the amplifying unit (20) according to the switching signal of the current presence detection unit (30); And And a failure display unit (80) displaying the number of failures by counting the output pulse of the failure detection unit (50). delete The method of claim 1, wherein the failure detection unit 50 A second switch (SW2) for switching according to the level signal of the current comparator 40; Charge-discharge circuits (R62, R63, C61) for generating pulses through charging and discharging signals through the second switch; A counter (51) which counts each time the pulse signal is input by the charge / discharge circuit and continuously maintains a high level to a plurality of output terminals (Q1 to Q8); And a dip switch (52) for selecting one of the plurality of output stages of the counter (51). The method of claim 1, wherein the switching control unit 70 Switches 71 and 72 for switching according to the level signal of the fault determination unit 60; A relay (73) for providing a contact on or off signal to the first switch (SW1) in association with a switching operation of the switch; And a light emitting diode (74) indicating a failure in association with the switching operation of the switch.

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