KR20230092229A - Motor control device of star-delta starting type with safety function - Google Patents

Abstract

The present invention outputs a pre-switching signal that turns on the main magnetic contactor for a very short time whenever the motor is started, and the current flowing in the motor when the pre-switching signal is output It relates to a star-delta starting type motor control device with a safety function that detects and determines contact failure of a star magnet contactor or delta magnetic contactor, informs the contact failure, and stops motor operation.

Description

Star-delta starting type motor control device with safety function {Motor control device of star-delta starting type with safety function}

The present invention relates to a star-delta starting motor control device, and more particularly, to a pre-switching device that turns on a main magnetic contactor for a very short time whenever a motor is started. ) signal, and detects the current flowing in the motor when the free switching signal is output to determine the contact failure of the star magnet contactor or the delta magnet contactor, informs the contact failure, and stops the motor operation. It relates to a start-up motor control device.

In general, looking at the star-delta starting method of a three-phase motor, first, the star magnetic contactor (hereinafter referred to as 'contactor') and the main contactor are switched on at the same time, then the star contactor is turned off and the delta contactor is turned on after a certain period of time. When the motor is stopped, the main contactor and the delta contactor are turned off at the same time to stop the motor.

However, in this conventional starting method, the star and delta contactors, which have a relatively smaller contact capacity than the main contactor, inevitably have a relatively large impact during on/off switching.

In other words, when the contactor is turned on or off, a very large surge occurs, and the switch contact point gradually wears out and begins to deform, and if the deformation of the contact point becomes severe during long-term use, the current flow is restricted or fixed, making it impossible to block (off) will do

This phenomenon causes a short circuit of the power line to cause a large-scale accident such as a fire, or affects productivity due to a decrease in the operation rate of facilities due to motor burnout.

Therefore, in order to minimize the switch contact failure of such a magnetic contactor, there is Korean Patent Publication No. 10-2018-0009132 (star-delta motor start control device) proposed by the present inventors.

In the prior art, when starting a motor, a star contactor or delta contactor having a relatively small contact capacity is first turned on for a very short time (0.1 sec), and then the main contactor is turned on, and when the motor is stopped, the main contactor is first turned off and then By driving the star contactor or delta contactor off after a very short time (0.1sec), the main circuit breaker with a large contact capacity is directly responsible for the power on and off, so that the star contactor or delta contactor with a relatively small contact capacity that was made to protect it.

Therefore, the contact life of the star contactor or the delta contactor is increased by the prior art, but also, when used for a long time, as described above, a problem of wear or sticking according to the contact life of the contactor switch occurs.

Patent Publication No. 10-2018-0009132, Utility Model Registration No. 20-0308097, No. 10-0687653

The present invention was invented to solve the above problems, and an object of the present invention is a main contactor switch interposed between a three-phase power terminal and one end of a three-phase motor, a star contactor switch connected to the other end of the motor, and Including a wiring structure of a three-phase motor consisting of a delta contactor switch unit connected in parallel to both ends of the motor and a current detector interposed between the power terminal and the main contactor switch unit,

When the motor is started, a pre-switching signal that turns on the main contactor switch for a very short time is output, and when the pre-switching signal is output, the presence or absence of current flowing in the motor is detected to form a star magnet contactor or a delta magnet. It is characterized in that it includes a control unit for determining a contact failure of the contactor.

In addition, according to the present invention, a run / stop switch for inputting a key to run or stop the motor, a relay unit for driving the switching operation of the main contactor switch unit, the star contactor switch unit and the delta contactor switch unit, and the star contactor A display unit for displaying the contact failure of the switch unit or the delta contactor switch unit, and a control unit for displaying and stopping the motor startup when it is determined that the star contactor switch unit or the delta contactor switch unit has a contact failure Characterized in that it is further included.

In addition, according to the present invention, the current detector is characterized in that it detects the current flowing in the motor and inputs it to the control unit.

In addition, according to the present invention, the pre-switching signal is a signal for a period during which the main contactor switch unit is turned on, and is characterized in that it is 0.5 sec.

The present invention for achieving the above object outputs a pre-switching signal that turns on the main magnetic contactor for a very short time whenever the motor is started, and the pre-switching signal To provide a star-delta starting type motor control device with a safety function that detects the current flowing in the motor at the time of output, determines the contact defect of the star magnet contactor or the delta magnet contactor, informs the contact defect, and stops the motor operation. there is.

In this way, the present invention outputs a pre-switching signal that turns on the main magnet contactor for a very short time whenever the motor is started, and detects the current flowing in the motor when the pre-switching signal is output to form a star magnet contactor. Alternatively, it provides the advantage of determining the contact failure of the delta magnet contactor, informing the contact failure, and stopping the motor operation.

In addition, the present invention sets all set current and time value data related to motor protection as digital values through the control unit, and can be easily modified. It offers the advantage of being able to minimize economic losses.

1 is a circuit block diagram of a motor control device of a star-delta starting method having a safety function according to the present invention;
2 is a timing output diagram of a control unit according to the present invention;
Figure 3 (a) to (c) is a configuration diagram when the contactor switch contact failure according to the present invention,
4 is a control procedure of a motor control device of a star-delta starting method having a safety function according to the present invention.

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

First, in adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible, even if they are displayed on different drawings. And, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

1 is a circuit block diagram of a motor control device of a star-delta starting method having a safety function according to the present invention.

As shown, the motor control device of the star-delta starting method having the safety function of the present invention,

The main contactor switch unit (MS) interposed between the three-phase power terminals (R, S, T) and one end (U, V, W) of the three-phase motor (M), and the other end (X, A star contactor switch unit (SS) connected to Y and Z), a delta contactor switch unit (DS) connected in parallel to both ends of the motor (M), the power terminals (R, S, T) and the main contactor It includes a wiring structure of a three-phase motor (M) consisting of a current detector (CT) interposed between the switch unit (MS),

Switching operations of the run/stop switch 10 for key inputting the run or stop command of the motor M and the main contactor switch unit MS, star contactor switch unit SS and delta contactor switch unit DS The relay unit 20 that drives the relay unit 20, the display unit 30 that displays when the contact of the star contactor switch unit SS or delta contactor switch unit DS is defective, and a plurality of keys are provided and various setting values are set. outputs a pre-switching signal that turns on the main contactor switch (MS) for a very short time when the setting unit 40 and the motor (M) are started, and outputs the pre-switching signal includes a control unit 50 that detects the presence or absence of current flowing in the motor M when determining the contact defect of the star magnet contactor or the delta magnet contactor, and displays and stops the motor start-up if it is determined that the contactor has a contact defect. do.

The current detector (CT) detects the current flowing in the motor (M) and inputs it to the controller (50).

For example, the current detector CT uses two current detectors 2CT and is configured to detect R-phase and T-phase currents.

The run/stop switch 20 inputs an operation command according to the start and operation of the motor M or a stop command according to the stop of operation to the input port P1 of the controller 50.

The relay unit 20 includes a main contactor relay (ML), a delta contactor relay (DL) and a star contactor relay (SL) connected to the output port (P2) to the output port (P4) of the control unit 50. .

When the control unit 50 outputs a high signal to the output port P2, the main contactor relay ML is excited and the main contactor switch unit MS is turned on.

In addition, in the same way, when the control unit 50 outputs a high signal to the output ports P3 and P4, the delta contactor relay DL and the star contactor relay SL are excited and the delta contactor switch unit DS and the star contactor switch The sub (SS) is turned on, respectively.

The display unit 30 performs a corresponding display when the contact of the star contactor switch unit (SS) or the delta contactor switch unit (DS) is defective by the control output of the control unit 50.

Therefore, the user can check the contents displayed on the display unit 30 and take measures (exchange or repair) according to the contact failure of the star contactor switch unit (SS) or the delta contactor switch unit (DS).

The setting unit 40 is configured to perform all settings related to motor protection with a plurality of keys.

The settings may include load current setting of the motor M, star-delta connection conversion time setting, motor rated current setting, fault current (overcurrent) setting, abnormal current allowable time setting, and pre-switching signal time setting.

As shown in (a) of FIG. 2, when an operation command is input from the run/stop switch 10 to the input port P1 at the time point t1, the control unit 50 switches the main contactor switch to the output port P2 ( It outputs a pre-switching signal to turn on the MS for a very short time.

Therefore, the controller 50 outputs a high signal to the output port P2 to excite the main contactor relay ML to turn on the main contactor switch MS as shown in FIG. 2(b).

The pre-switching signal becomes a signal of a period (t1 to t2) during which the main contactor switch unit (MS) is turned on, and may be, for example, 0.5 sec.

Then, the controller 50 detects the flow of current to the motor M input through the current detector CT.

For example, as shown in FIG. 1, if both the star contactor switch unit (SS) and the delta contactor switch unit (DS) maintain the off state, which is the normal initial state, even if the main contactor switch unit (MS) is turned on, the motor (M ), no current flows.

Therefore, if the current is not detected through the current detector (CT) after outputting the pre-switching signal, it is determined as a normal state and proceeds to the next step for starting the motor.

However, when the current flow of the motor M is detected through the current detector CT,

For example, as shown in FIG. 3 (a), when some switches of the delta contactor switch unit (DS) are turned on due to contact failure (E) or a part of the star contactor switch unit (SS) as shown in FIG. 3 (b) When the switch is turned on due to a contact failure (E), current flows through the motor (M).

In this way, when the current flow is sensed in the motor M after outputting the pre-switching signal, the control unit 50 determines that the star contactor or the delta contactor has a contact defect and outputs a failure state accordingly to the display unit 30.

After that, start control of the motor M is stopped.

On the other hand, as described above, when the current is not detected through the current detector (CT) after the pre-switching signal is output, in the normal state, after the output of the pre-switching signal is completed as shown in FIG. , as shown in FIG. 2 (c), after turning on the star contactor switch unit (SS) first at the time point (t3), and then turning on the main contactor switch unit (MS) at the time point (t4) after a short period of time (0.1 sec) and, at the time of delta connection conversion, the main contactor switch unit (MS) is first turned off at the time point (t5) before the start of the star connection is completed (0.1sec), and then the star contactor switch unit (SS) is turned off at the time point (t7) Then, as shown in (d) of FIG. 2, the delta contactor switch unit (DS) is first turned on, and then the main contactor switch unit (MS) is turned on after a short period of time (0.1 sec) to complete the start-up.

When the motor is stopped later, the main contactor switch unit (MS) is first turned off at the stopping point (t9) as shown in FIG.

In addition, according to the present invention, the alarm unit 60 is further configured to generate an alarm that can notify the outside when the contact of the star contactor switch unit (SS) or the delta contactor switch unit (DS) is defective after outputting the pre-switching signal. let me do it

Hereinafter, the premise operation of the present invention configured as described above will be described with reference to the flowchart of FIG. 4 .

First, when the run/stop switch 10 is turned on and an operation start command is input to the input port P1 of the controller 50 (step S10), the controller 50 sends the main contactor switch (MS) to the output port P2. ) is turned on for a very short time (for example, 0.5 sec) to output a pre-switching signal to give. (Step S20)

The high signal output through the output port (P2) excites the main contactor relay (ML) to turn on the main contactor switch (MS).

At this time, the controller 50 detects the current flow to the motor M through the current detector CT (step S30).

When the current flow of the motor M is detected in the step S30, the controller 50 determines whether the delta contactor switch unit DS has a contact defect, or the star contactor switch unit SS contact defect, or the star contactor switch It is determined that the contact of the unit (SS) and the delta contactor switch unit (DS) is defective, and the start control of the motor is stopped (step S40).

Then, the failure indication according to the above step (S40) is output to the display unit 30.

On the other hand, if the current is not detected through the current detector (CT) after the pre-switching signal is output in the above step (S30), it is determined that it is in a normal state and proceeds to the next step for starting the motor (step S60).

In the above, limited embodiments of the present invention have been described, but those skilled in the art should note that the present invention is not limited thereto and various embodiments are expected.

MS: main contactor switch part SS: star contactor switch part
DS: delta contactor switch CT: current detector
M: motor 10: run/stop switch
20: relay unit 30: spread unit
40: setting unit 50: control unit
60: alarm unit

Claims (4)

The main contactor switch unit (MS) interposed between the three-phase power stage (RST) and one end (U, V, W) of the three-phase motor (M), and the other end (X, Y, Z) of the motor (M) A star contactor switch unit (SS) connected to, a delta contactor switch unit (DS) connected in parallel to both ends of the motor (M), the power terminals (R, S, T) and the main contactor switch unit (MS) ) Including a wiring structure of a three-phase motor (M) consisting of a current detector (CT) interposed between,
When the motor (M) starts, a pre-switching signal that turns on the main contactor switch (MS) for a very short time is output, and when the pre-switching signal is output, the amount of current flowing in the motor (M) A star-delta starting type motor control device with safety function, characterized in that it comprises a control unit 50 for detecting the presence or absence of a contact defect of a star magnet contactor or a delta magnetic contactor.
The method of claim 1,
Switching of the run/stop switch 10 for key inputting the run or stop command of the motor M and the main contactor switch unit MS, star contactor switch unit SS and delta contactor switch unit DS The relay unit 20 that drives the operation, the display unit 30 that displays when the contact of the star contactor switch unit (SS) or the delta contactor switch unit (DS) is defective, and the star contactor switch unit (SS) or the delta contactor switch unit (DS) A star-delta starting type motor control device with safety function, characterized in that it further includes a control unit 50 for displaying it and stopping the motor starting when it is determined that the contact of the contactor switch unit (DS) is defective.
The method of claim 1,
The current detector (CT) detects the current flowing in the motor (M) and inputs it to the control unit (50).
The method of claim 1,
The free switching signal is a signal for a period in which the main contactor switch unit (MS) is turned on and is a star-delta starting motor control device having a safety function, characterized in that 0.5 sec.

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