KR101389793B1 - Apparatus and method for monitoring and analyzing motor - Google Patents

Abstract

Disclosed is an apparatus and a method for monitoring and analyzing a motor. The present invention can calculate power by multiplying voltage and current which are inputted to the motor when the operation state of the motor is in an active state, add the calculated power to an accumulated power, find the value of a phase of the voltage and current inputted thereto, find the retardation value by subtracting the phase right before the motor starts operating, and determine the abnormality of the starting characteristics of the motor if the retardation value is greater than a set retardation value. [Reference numerals] (10) Matching unit; (20) A/D converting unit; (31) Start judgment unit; (32) Start energy calculator; (33) Determination unit; (34) Start parameter calculator; (4) Top system; (40) Communications unit; (50) Storage unit; (60) Display unit; (70) RTC unit

Description

Apparatus and method for monitoring and analyzing electric motors {APPARATUS AND METHOD FOR MONITORING AND ANALYZING MOTOR}

The present invention relates to apparatus and methods for monitoring and analyzing electric motors.

In general, 20% of the total energy consumed in our country is consumed by various electric motors, and if it is limited to electric energy, about 67% of electric energy is consumed by electric motors. For motors that play such an important role, they have traditionally been managed / operated by replacing them in the event of a failure.

The reason why the motor is neglected to operate is that there is almost no failure in the motor at the initial stage of installation, and the cost and means for monitoring the occurrence of a defect inside the motor are not appropriate.

1 is a configuration diagram of a failure monitoring system of a conventional electric motor.

As shown in the figure, in a system for monitoring a failure of a conventional motor, an electronic overcurrent relay (EOCR) or a protective relay 3 monitors the overcurrent of a power source connected to the motor 1, and the like. In the case of a predetermined size or more, the circuit breaker or the electromagnetic contactor (MC) 1 transmits a trip signal to cut off the power supply.

However, such a conventional method cannot monitor a defect state in which the motor 1 progresses due to a failure, and when a failure occurs, the circuit breaker 2 is operated to disconnect the power and then replace the motor 1. Therefore, in the case of an important production facility, there is a problem in that the operation is stopped and economic damage occurs.

In general, when the motor is started in a stopped state, a large force is required, and a maximum of 4 to 7 times the starting current of the rated current flows. Therefore, a large number of failures occur at the time of starting the motor, or defects inside the motor may occur, which can be advanced as a failure.

In order to reduce the starting current of the motor, various methods such as YD start and inverter start are used. However, the start current cannot be reduced below the rated current, and the start time is increased when the start current is decreased.

The technical problem to be solved by the present invention is to monitor the power energy change and the current phase change characteristics generated when the motor is started, and to inform that the abnormality has occurred when the deviation from the normal starting characteristics occurs, the motor can progress to a failure To provide a motor monitoring / analysis apparatus and method for monitoring.

In addition, another technical problem to be solved by the present invention is to provide a motor monitoring / analysis apparatus and method for analyzing abnormal starting characteristics by recording the change and phase of the voltage, current and power generated when the motor is started.

In order to solve the above technical problem, the motor monitoring / analyzing apparatus of the present invention, when the current input to the motor increases from the initial current is determined to be a starting state, the current input to the motor exceeds the rated current If the first determination unit to determine the starting transient state; A first calculator configured to calculate starting power by using a voltage and a current input to the motor; A second calculator configured to calculate a start parameter of the motor when the motor is in a start state or a transient state of the motor; And a second determination unit for determining an abnormality in the starting characteristic of the motor with reference to the starting power calculated by the first calculating unit and the starting parameter calculated by the second calculating unit.

In one embodiment of the present invention, the second determination unit, when the amount of change in the starting power calculated by subtracting the accumulated power at the previous start from the accumulated power accumulated in the starting power calculated by the first calculator is greater than the set change amount, The abnormality in the starting characteristics of the motor can be judged.

In one embodiment of the present invention, the starting parameter may include an average voltage (RMS) of voltage and current, a phase of the voltage and current, a power, and a power difference obtained by subtracting power at the last start from the power.

In an embodiment of the present disclosure, the second determination unit may determine an abnormality in starting characteristics of the motor when the phase difference obtained by subtracting the phase of voltage and current at the time of immediately preceding starting from the phase of the voltage and current is greater than a set phase difference. Can be.

In one embodiment of the present invention, the matching unit for receiving and matching the voltage and current input to the motor; And a converter configured to convert the voltage and current matched by the matcher into digital data.

In one embodiment of the present invention, the storage unit for storing the starting power and the starting parameter; And a communication unit for transmitting an abnormality in the starting characteristic of the electric motor to a higher system.

In one embodiment of the present invention, it may further include a display unit for displaying to the user the abnormality of the starting characteristics of the motor.

In addition, in order to solve the above technical problem, the motor monitoring / analysis method of the present invention, when there is a current input to the motor, the operation state information of the motor is started, the operation state information of the motor is started Determining the status; Calculating electric power by multiplying a current and a voltage input to the electric motor; Adding the calculated power to the cumulative power; Obtaining a phase difference of a voltage and a current input to the electric motor, subtracting a phase at the time of immediately preceding start, and obtaining a phase difference therefrom; And determining the abnormality of the starting characteristic of the motor when the phase difference is greater than the set phase difference.

In one embodiment of the present invention, if the operation state information of the motor is a stop state, the current input to the motor is greater than the rated current, may further comprise the step of determining the operating state of the motor as a starting transient state have.

In one embodiment of the present invention, when the operating state information of the motor is not a stop state, when the operating state information of the motor is a starting transient state, when the current input to the motor is less than the rated current, starting the motor Accumulating power to obtain cumulative power; Calculating a change amount of starting power by subtracting the stored cumulative power at the previous start from the accumulated power; And determining the abnormality of the starting characteristic of the motor when the amount of change in the starting power is greater than the set amount of change.

As described above, the present invention accumulates the starting power of the motor, and is connected to the motor or the motor during starting when excessive starting power is consumed under the same load condition or when the phase change of the current is large compared with the current phase recorded at the last starting. By determining that an abnormality has occurred in the load, it is possible to detect an early failure or a defect of the motor generated during starting.

In addition, startup parameters such as voltage, current, phase angle, power, and power difference measured on a cycle-by-cycle basis can be recorded during start-up to analyze the cause of an error in the change of start-up power or phase change of current which is determined to be abnormal. .

1 is a configuration diagram of a failure monitoring system of a conventional electric motor.
2 is an exemplary view of a waveform diagram of a starting characteristic power of a general electric motor.
3 is a block diagram of a motor monitoring / analysis apparatus according to an embodiment of the present invention.
4 is a flowchart illustrating a motor monitoring / analysis method according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating a method of storing a startup parameter by the startup parameter calculator of FIG. 3.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The present invention focuses on the fact that the motor consumes a lot of energy due to a failure or an overload in the motor when the motor is started. 2 is an exemplary view of a waveform diagram of a starting characteristic power of a general electric motor.

In view of the above, the present invention accumulates the starting power, which is the starting energy of the motor, and compares the difference between the accumulated value stored immediately before and the current accumulated value, and determines that an abnormality has occurred when excessive power is accumulated. It is to analyze whether the energy consumption is large due to the failure of the motor or the overload by using the starting parameters recorded in the meantime.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a block diagram of a motor monitoring / analysis apparatus according to an embodiment of the present invention. As shown in FIG. 1, an EOCR / protective relay (3) may be used to monitor and analyze starting characteristics of a motor at an inlet of the motor 1. ) May be provided inside. It may also communicate with higher-level systems (not shown) via wired or wireless networks.

The monitoring / analysis apparatus of the present invention receives a voltage input to the electric motor 1 from a potential transformer (PT) 4 and a current from a current transformer (CT) 5. .

As shown in the figure, the motor monitoring / analysis apparatus of an embodiment of the present invention, matching unit 10, analog / digital (A / D) conversion unit 20, control unit 30, communication unit 40, a storage unit 50, a display unit 60, and a real time counter (RTC) unit 70.

The matching unit 10 matches the input voltage and current signals, and the A / D converter 20 converts the voltage and current signals matched by the matching unit 10 into digital data.

The control unit 30 includes a start determination unit 31, a start energy calculation unit 32, a determination unit 33 and a start parameter calculation unit 34 as shown in the figure.

The start-up determination part 31 starts the operation state of the electric motor 1 when the electric motor 1 starts starting under the condition which the electric motor 1 stops and an electric current does not flow, and the operation state of the electric motor 1 is started. When the three-phase current input to the motor 1 exceeds the rated current, it is determined that the operating state of the motor 1 is a starting transient state.

Starting energy calculation unit 32 may calculate the power by the product of the input voltage and the current by the following equation (1) in order to calculate the power required for starting the electric motor (1). The voltage input to the motor 1 can be received from the PT 4, and the current input to the motor 1 can be received from the CT 5.

The starting parameter calculation unit 34 analyzes the starting characteristic in the case of starting abnormality and, when the operating state of the motor 1 is in the starting state or the starting transient state, an average of voltage and current (Root-Mean-Square; RMS) In addition, a startup parameter such as a power difference obtained by subtracting power at the last startup from the phase, power, and power of voltage and current is calculated, and the calculated startup parameter is stored in the storage unit 50.

RMS of voltage and current can be calculated by the following equations (2) and (3).

In this case, N is the number of samples per cycle.

The phase of the voltage and current can be calculated by the following equation (4).

In this case, Real and Imag are the magnitude of the vector of voltage or current, and are defined as follows.

Where K is the sample number and N is the number of samples per cycle.

The determination unit 33 of the electric motor 1 when the amount of change in the starting power calculated by subtracting the accumulated power at the previous start from the accumulated power accumulated in the starting power calculated by the starting energy calculation unit 32 is greater than the set change amount. It may be determined that the maneuver characteristic is abnormal and the abnormality information is transmitted to the host system, or the display unit 60 may be controlled to indicate that an abnormality has occurred in the maneuver characteristic.

In addition, the determination unit 33 determines that the phase difference obtained by subtracting the phase of the voltage and current at the time of immediately preceding start from the phase of the voltage and current is greater than the set phase difference, and thus the abnormality information differs from the starting characteristic. It may be transmitted to the system or the display unit 60 may be controlled to indicate that an abnormality has occurred in the starting characteristic.

The communication unit 40 transmits the information processed by the control unit 30 to the upper system through the network.

The storage unit 50 stores the starting power calculated by the starting energy calculating unit 32 and the starting parameter calculated by the starting parameter calculating unit 34.

The display unit 60 is disposed on the front surface, and under the control of the determination unit 33, the display unit 60 can display the information processed by the determination unit 33 and the unique operation and setting information of the electric motor 1.

The RTC unit 70 also manages the time of the EOCR / protective relay 3 in which the present invention is provided.

In order to monitor the starting characteristic of the electric motor 1, the present invention having such a configuration accumulates starting power, so that excessive starting power is consumed under the same load condition, or the phase change of current compared with the current phase recorded at the last starting. When is large, it is determined that an abnormality has occurred in the motor 1 or the load connected to the motor 1 during start-up, the abnormality is displayed on the display unit 60 so that the operator can view it, or communicate with the host system through communication. Error information can be transmitted.

In addition, start-up parameters such as voltage, current, phase angle, power, and power difference, which are measured in units of cycles, are recorded during start-up, so that the cause of abnormality can be analyzed when the start-up power or the phase change of the current is judged to be abnormal. Startup parameters may be provided.

Therefore, the present invention can detect and analyze a failure or a defect in the interior of the motor 1 occurring early during the start of the motor 1 at an early stage.

4 is a flowchart illustrating a motor monitoring / analysis method according to an embodiment of the present invention.

As shown in the figure, the monitoring / analysis method of an embodiment of the present invention first checks whether the three-phase current input to the electric motor 1 is zero (S1). As a result of checking in S1, when the three-phase current is 0, the state information of the motor 1 is changed to the stop state, and it is stored in the storage unit 50 (S17) and returned. As a result of checking in S1, when the three-phase current is not 0, it is checked whether the operation state information of the motor 1 is in a normal state (S2).

As a result of checking in S2, the operation state information of the motor 1 is returned in the normal state, and if it is not the normal state, it is checked whether the operation state information of the motor 1 is in the stopped state (S3).

As a result of checking in S3, when the operation state information of the motor 1 is in the stopped state, the operation state information of the motor 1 is stored in the storage unit 50 in the starting state (S4) and input to the motor 1. Check whether the magnitude of the three-phase current is greater than the rated current of the motor (1) (S5).

As a result of checking in S5, when the magnitude of the three-phase current input to the motor 1 is larger than the rated current, the operation state information of the motor 1 is stored in the storage section 50 in the starting transient state (S6), and the three-phase The three-phase power is calculated by multiplying the current and the voltage, and the calculated three-phase power and the accumulated power are added and stored in the storage unit 50 (S7). If the three-phase current input to the motor 1 is not greater than the rated current of the motor 1 as a result of checking in S5, the three-phase current is multiplied by the voltage to calculate the three-phase power, and the calculated three-phase power and the accumulated power are calculated. In addition, it is stored in the storage unit 50 (S7).

Then, the phase of the voltage and current in the vector format input from the PT (4) and CT (5) is calculated. The phase of the voltage and current can be obtained by Equation 4 above.

Subsequently, a phase difference is generated by subtracting the stored phase at the last startup from the calculated phase and storing it in the storage unit 50 (S8). When the phase difference calculated in S8 and the set phase difference are compared (S9), and when the phase difference calculated in S9 is larger than the set phase difference, it is determined that an abnormality has occurred, and an alarm is generated through the display unit 60 and the motor ( The state information of 1) is stored in the storage unit 50 in an abnormal state (S10) and returned. At this time, the abnormal state can be notified to the upper system through the communication unit 4. As a result of the comparison of S9, when the phase difference calculated in S8 is not larger than the set phase difference, it returns.

On the other hand, when the operation state information of the electric motor 1 is not a stop state as a result of confirmation of S3, it is confirmed whether the operation state information of the electric motor 1 is a starting transient state (S11). As a result of checking in S11, when the operation state information of the electric motor 1 is not a starting transient state, it progresses to S5. When the operation state information of the motor 1 is a starting transient state as a result of checking in S11, it is checked whether the three-phase current input to the motor 1 is smaller than the rated current (S12).

As a result of checking in S12, when the three-phase current input to the motor 1 is not smaller than the rated current, the process proceeds to S7. When the three-phase current is smaller than the rated current, the operation state information of the motor 1 is stored in the normal state. It stores in 50 (S13).

 Thereafter, the accumulation of starting power at the start of the electric motor 1 is completed (S14), and the amount of change in starting power is calculated by subtracting the stored cumulative power at the time of immediately preceding start from the accumulated power (S15). Check whether the change amount of the starting power is greater than the set power change amount (S16), and if it is large, determine that an abnormality has occurred, generate an alarm through the display unit 60, and store the state information of the motor 1 in an abnormal state. 50) (S10) and return. At this time, the abnormal state can be notified to the upper system through the communication unit 4.

As a result of checking in S16, when the amount of change in starting power is not greater than the set amount of change in power, it returns.

In the description of FIG. 4, each confirmation and comparison is described as being sequential, but the order of confirmation and comparison is not limited to the ones listed therein, and the order may be changed.

FIG. 5 is a flowchart illustrating a method of storing the startup parameter by the startup parameter calculator 34 of FIG. 3.

As shown in the figure, the startup parameter calculation unit 34 of one embodiment of the present invention checks whether the operation state information of the electric motor 1 is a start state or a transient state of operation (S21). As a result of checking in S21, when the operation state information of the electric motor 1 is neither a starting state nor a transient state, it returns.

As a result of checking in S21, when the operation state information of the electric motor 1 is a starting state or starting transient state, one cycle of the output value of the A / D conversion part 20, ie, the voltage or electric current of the electric motor 1, is performed. Check whether or not is completed (S22). As a result of checking in S22, when one cycle is not completed, the storage unit 50 stores the sample values of voltage and current (S27) and returns.

As a result of checking in S22, when one cycle is completed, the RMS of voltage and current is calculated using a sample of one cycle (S23), and the phases of voltage and current are calculated (S24).

Thereafter, the three-phase power is calculated using the RMS and the phase of the voltage / current (S25), and the power difference is calculated by subtracting the stored power at the last start from the three-phase power calculated in S25 (S26) and returning.

In this way, the startup parameter calculator 34 may store parameters at startup or overrun.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined by the following claims.

1: motor 3: EOCR / protective relay
4: PT 5: CT
10: matching unit 20: A / D conversion unit
30: control unit 31: start determination unit
32: mobile energy calculation unit 33: determination unit
34: start parameter calculator 40: communication unit
50: storage unit 60: display unit
70: RCT Department

Claims (10)

A first judging unit which determines that the current input to the motor is a starting state, and determines the starting state when the current input to the motor exceeds a rated current;
A first calculator configured to calculate starting power by using a voltage and a current input to the motor;
Calculating a starting parameter including an average of voltage and current (RMS), a phase of voltage and current, power and a power difference obtained by subtracting electric power at the time of immediately preceding starting in the electric power in the starting state or the transient state of the motor; 2 calculation unit; And
A second determination unit for determining an abnormality in the starting characteristic of the electric motor, with reference to the starting power calculated by the first calculating unit and the starting parameter calculated by the second calculating unit;
The second judging unit judges an abnormality in the starting characteristic of the motor when the amount of change in starting power that is obtained by subtracting the cumulative power at the previous start from the accumulated power accumulated in the starting power calculated by the first calculating unit is greater than the set change amount. And an electric motor monitoring / analyzing device for determining an abnormality in starting characteristics of the electric motor when a phase difference obtained by subtracting the phases of voltage and current at the time of immediately preceding start from the phase of the voltage and current is greater than a set phase difference.
delete delete delete The method of claim 1,
A matching unit configured to receive and match a voltage and a current input to the electric motor; And
And a converting unit converting the voltage and current matched by the matching unit into digital data.
The method of claim 1,
A storage unit which stores the starting power and the starting parameter; And
And a communication unit for transmitting an abnormality in the starting characteristic of the motor to a higher system.
The method of claim 1,
And a display unit for displaying to the user an abnormality in the starting characteristics of the motor.
Determining whether operation state information of the motor is stopped when there is a current input to the motor;
Judging whether the motor is in the stopped state, and determining the operating state information of the motor as the start state in the stopped state;
Judging whether the motor is in the stopped state, when the motor is in the stopped state and the current input to the motor is greater than the rated current, determining the operating state of the motor as the starting transient state;
Calculating power by multiplying a current and a voltage input to the motor;
Adding the calculated power to the cumulative power;
Calculating a change amount of starting power by subtracting the stored cumulative power at the previous start from the accumulated power;
Determining an abnormality in the starting characteristic of the motor when the amount of change in starting power is greater than a set amount of change;
Obtaining phases of voltages and currents input to the motors, and subtracting phases of voltages and currents at the time of immediately preceding starting therefrom to obtain phase differences; And
And determining the abnormality of the starting characteristic of the motor when the phase difference is greater than the set phase difference. delete delete

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