JPH0923672A - Starter of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent two or more motors from being started concurrently when driving a plurality of motors intermittently. SOLUTION: Starting magneto-switches S1 -Sn are connected respectively via respective inverse-parallel-connection thyristor switches in parallel with operating magneto-switches B1 -Bn provided in respective motors M1 -Mn . Then, the soft start of the desired motor M1 is performed by closing the starting magneto-switch S1 to bring the inverse-parallel-connection thyristor switch into its continuity state, and the motor M1 is brought into its rated driving state by the operating magneto-switch B1 after the elapse of a predetermined overlapping term. The starting magneto-switches S2 -Sn of the other motors M2 -Mn are remained open until the motor M1 is brought into its rated driving state. Since the two or more motors are never started concurrently, no large current is made to flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting device for soft starting a plurality of motors, and more particularly to a starting device for preventing a plurality of motors from starting at the same time when starting or restarting a desired motor.

[0002]

2. Description of the Related Art Conventionally, when starting a three-phase motor of several tens of horsepower or more, a Y-Δ starting method or a kondorfa starting method and a reactor starting method based on the principle of an autotransformer are mainly used. However, these conventional starting methods are common technologies in that the applied voltage at the time of starting the three-phase motor is reduced by changing the connection state at the time of starting and at the time of rated operation, and the starting current is suppressed to be small. .

However, in the method of changing the connection state to reduce the applied voltage, electric power is supplied from the starting circuit and other control circuits at the time of starting, while electric power is directly supplied from the power source at the time of rated operation. It was necessary to turn on / off mechanical contacts such as an electromagnetic relay and an electromagnetic magnet switch for switching the current path between the time and the rated operation.

As a result, arc discharge occurs when the mechanical contacts are turned on and off, and a large current more than the rated value is likely to flow at the time of start-up, resulting in very fast contact wear. In particular, when switching the connection state, the magnitude of the current also suddenly changes and an inrush current flows, which often adversely affects the power supply and the motor.

A conventional technique for switching such a connection state will be specifically described with reference to the block diagrams of FIGS. 10A to 10C, taking the Y-Δ starting method as an example. FIG. 10 (a)
105 is a three-phase motor, and has three inductive loads 104 ₁ , 104 ₂ and 104 ₃ when shown by an equivalent circuit.

One end of each of the inductive loads 104 _{1 to} 104 ₃ is connected to the R, S, and T phases of a three-phase power source via a three-contact electromagnetic relay box 106, and the other end is connected to 3
It is connected to the neutral point O via a contact electromagnetic relay box 107, and the other end is connected to the electromagnetic relay box 108.
Are connected to the T-phase, the R-phase, and the S-phase of the power supply voltage, respectively.

Therefore, the contacts of the relay box 108 are opened, and the electromagnetic relay boxes 106, 1 are opened.
When the contacts 07 are closed, the inductive loads 104 _{1 to} 104 ₃ are Y-connected (star connection), and the contacts of the electromagnetic relay box 107 are closed, as shown in FIG. The electromagnetic relay box 10 with the open state.
When the contacts 6 and 108 are closed, the inductive loads 104 _{1 to} 104 ₃ are Δ-connected as shown in FIG.
(Delta connection).

When the inductive loads 104 _{1 to} 104 ₃ are Y-connected when the three-phase motor 105 is started, the current I ₁ (A) flowing through the motor 105 is
When the rated voltage between lines of the three-phase power supply is V _r and the impedance of one phase of each of the inductive loads 104 _{1 to} 104 ₃ is Z (Ω), it can be expressed by the following equation. I ₁ = (V _r / √3) / Z (1)

On the other hand, when the three-phase motor 105 is started and the inductive loads 104 _{1 to} 104 ₃ are connected by the Δ connection, a current I flowing through the motor 105 is obtained.
₂ can be expressed by the following equation. I ₂ = (V _r · √3) / Z (2) Therefore, I ₂ / I ₁ = ⅓ (3)

As described above, each of the inductive loads 104 ₁ ...
The magnitude of the current when the 104 ₃ is Y-connected is 1/3 times the magnitude of the current when the Δ-connected.

Generally, when the rated voltage is applied to the motor immediately after the motor is stopped, a starting current several times as large as the rated current flows, which damages the power supply system or causes excessive torque, which adversely affects the load. Therefore, even if it is desired to use the Δ connection that allows a large current to flow and a large torque during the rated operation, the starting current can be reduced to 1/3 when the Y connection is used at the start.
Further, since the torque is proportional to the square of the supply voltage, the magnitude of the torque in that case also becomes 1/3.

However, when converting the Y connection to the Δ connection, if the three contacts of the relay box 107 are opened to release the Y connection, each of the inductive loads 104 _{1 to} 104 ₃ is opened. Is temporarily disconnected from the three-phase power supply. In this case, each of the inductive loads 1
04 _1-104 for induced electromotive force is generated in the _3, when the contacts of the relay box 108 is in the closed state to make the Δ connection, large is the phase difference between the 3-phase supply voltage Inrush current may flow.

FIG. 11 shows a change in current when the three-phase motor 105 is started by the Y-Δ starting method.
It can be seen that when the Y connection is released at time P ₁ and the operation due to the Δ connection is started at time P ₂ , the current continues to increase until time P ₃ and a very large inrush current flows.

The generation of such a rush current or arc discharge deteriorates the power supply and the motor, and shortens the life.
In addition, in actual work, it is often the case that multiple 3-phase motors are used at the same time, so deterioration of life imposes a heavy burden on equipment maintenance costs, and efficiency deterioration at startup is ignored when the number of 3-phase motors increases. I couldn't do that, which was a big problem.

Particularly, according to the prior art, a plurality of three-phase motors are used, and desired three-phase motors are started in a desired order.
In addition, when it is desired to stop and restart in a desired order, the same number of starting devices as the number of three-phase motors are required. In this case, when a plurality of three-phase motors are simultaneously started or restarted, the inrush current at the time of starting will flow for that number of units, and if the power supply capacity is exceeded, other equipment due to a power supply voltage drop will occur. It was a serious problem in terms of adverse effects on the product and safety.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above disadvantages of the prior art, and its object is to provide a motor starter capable of soft-starting a plurality of motors in a desired order. is there.

[0017]

In order to solve the above-mentioned problems, the invention according to claim 1 is a motor starting device for starting a plurality of motors, the motor starting devices being provided in accordance with the number of the motors, each motor being a power source. An operating magnet switch connected to the operating magnet switch, a starting magnet switch connected in parallel to each of the operating magnet switches, a thyristor reverse parallel connection switch inserted between each of the starting magnet switches and the power source, and the plurality of starting An interlock circuit that is activated when one starting magnet switch of the magnet switches is closed, and maintains the open state of the other starting magnet switch while the starting magnet switch is closed. And has the starting magnet switch provided on one motor closed. Then, the thyristor anti-parallel connection switch is turned on, the thyristor anti-parallel connection switch is controlled to gradually increase the voltage applied to the motor, and the thyristor anti-parallel connection switch is fully turned on. After a predetermined overlap period with the magnet switch closed, the thyristor anti-parallel connection switch is cut off, the starting magnet switch is opened, and the motor is rated by the operating magnet switch. The motor starting device is characterized in that the start of the other motor is not started by the operation of the interlock until the start of the one motor is completed.

The invention according to claim 2 is the motor starting device according to claim 1, further comprising a sequencer in which an operation sequence for starting and restarting the plurality of motors is stored, and the operation is performed. The sequencer is configured to close the start magnet switch in a closed state in order to automatically start and restart the plurality of motors, and by the operation of the interlock circuit,
It is characterized that it is prevented that two or more starting magnet switches are accidentally closed at the same time.

According to such a configuration of the present invention, the operating magnet switches are provided according to the number of the motors provided, and the operating magnet switches are closed to connect the motors to the power source. In the rated operating state, it becomes possible to directly supply electric power from the power supply voltage to each of the motors.

On the other hand, a starting magnet switch connected in parallel to each of the operating magnet switches is provided,
Since a thyristor anti-parallel connection switch is inserted between each of the starting magnet switches and the power source, the starting magnet switch of the motor to be started is closed to make the thyristor anti-parallel connection switch conductive. At the time of starting, if the thyristor antiparallel connection switch is controlled to gradually increase the voltage, the electric power supplied from the power supply to the motor can be limited, and the inrush current does not flow immediately after starting, It is possible to perform a soft start of the motor.

At this time, if the starting magnet switch is closed and then the thyristor antiparallel connection switch is turned on, no voltage is applied to the contact of the starting magnet switch.

Since the operating magnet switch is closed after the thyristor antiparallel connection switch is in the all-on state (conducting for the entire period), no voltage is applied to the contact of the operating magnet switch, No contact wear.

After the thyristor anti-parallel connection switch is fully turned on and the operation magnet switch is closed for a predetermined time, the thyristor anti-parallel connection switch is turned off and the starting magnet switch is opened. Therefore, it is possible to reliably prevent the occurrence of arc discharge when the starting magnet switch is opened.

In this case, an interlock circuit is provided in this motor starting device, and when one of the plurality of starting magnet switches is in the closed state, the other starting magnet switch maintains the opened state. With this configuration, a plurality of motors do not start at the same time, and a large current is prevented from flowing.

Further, the motor starter having the interlock circuit is provided with a sequencer for storing the operation sequence for starting and restarting the plurality of motors.
When the starting magnet switch is closed and opened according to the operation sequence to automatically start and restart the plurality of motors, two or more erroneous operations are erroneously caused by the operation of the interlock circuit. It is possible to prevent two or more motors from starting at the same time because the starting magnet switches of are closed at the same time.

[0026]

Embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, 2 is an embodiment of the present invention,
an n-number of starting and motor starting device which performs a rated operation of the motor M ₁ ~M _n (3-phase AC induction motor).

This motor starting device 2 includes an electronic starter CSS, n starting magnet switches S _{1 to} S _n corresponding to the number of the motors M _{1 to} M _n , a main starting magnet switch A, and an operation. the magnet switch (magnet switch contacts are opened and closed by magnetic force) and a B ₁ .about.B _n, each motor M ₁ ~M _n, the operating magnet switch B ₁ .about.B _n are connected, the driving magnet Power supply (RST) (three-phase power supply) via switches B _{1 to} B _n
Of the power supply (RS) when each of the operating magnet switches B _{1 to} B _n is closed.
Power is supplied from T) and it is configured to operate at the rated power.

A thyristor anti-parallel connection switch 4 is provided inside the electronic starter CSS, and one end of the thyristor anti-parallel connection switch 4 is connected to the power source (RST) via a main starting magnet switch A. Has been done,
The other end is connected so as to correspond to the R, S, and T phases of the starting magnet switches S _{1 to} S _n connected to the motors M _{1 to} M _n .

The thyristor antiparallel connection switch 4 will be described. As shown in FIG. 3, two thyristors 1 are provided.
1 ₁ and 11 ₂ are connected in anti-parallel and inserted in the R phase,
In addition, thyristors 11 ₃ and 11 ₄ and thyristors 11 ₅ and 1
1 and ₆ are respectively connected in anti-parallel and are inserted in the S phase and T phase, and the electronic starter CSS controls the gate terminals of the thyristors 11 _{1 to} 11 ₆ to perform the trigger operation. It is configured so that the thyristor can be made conductive.

The motor starting device 2 magnetically controls the starting magnet switches S _{1 to} S _n , the operating magnet switches B _{1 to} B _n, and the main starting magnet switch A to establish an open state. It is configured to switch between the closed state and a specific control operation thereof will be described with reference to the internal block diagram of the motor starter 2 shown in FIG.

FIG. 2 shows a circuit necessary for starting the _three motors M _{1 to} M ₃ among the n motors and keeping them in the rated operation state, but other motors M ₄ ~
The circuits required for M _n are omitted to avoid repetition.

Referring to FIG. 2, SW ₁ is connected to an AC power source 31 (200 V AC 50/60 Hz: corresponding to R phase and T phase), which is a power source for a control device, and a starting circuit of the motor M ₁ . It is a changeover switch for switching to any of manual, remote, and OFF sides, and one end of the self-holding circuit 21 ₁ is connected to the manual side of the switching.

This self-holding circuit 21 ₁ is called a self-holding contact 22 ₁ (normally open contact: a contact) connected in parallel.
Unless otherwise specified, the contact is an a contact) and a manual on-switch PSW ₁ (push switch). The manual side for switching is connected to one end of the switch and the other end is normally closed. Off switch 24 ₁ (Normally closed contact: b
Contact) are connected in series, via the interlock circuit 26 ₁ of the motor M _1, a self-holding relay RO ₁ for closing said self-holding contact 22 _1, contact of the normally closed state in the 4
4 ₁ (contact b) is connected to the AC power supply 31. A desired motor can be started by using the manual on-switch PSW ₁ (push switch) as a selection means.

By the way, each motor M _k (1 ≦ k ≦ n)
Is provided with an interlock circuit 26 _k , and one interlock circuit 26 _m has a contact r ₁ which is opened by an interlock relay R _{k of} each motor M _k.
Of ~r _n, contacts r _m interlock relay R _m of the motor M _m of the circuit opens and closes (r _m is b contact)
Except the contacts r ₁ to r _n are connected in series in the interlock circuit 26 _1. Therefore, the contacts r _{2 to} rn except the contact r ₁ are connected in series.

In the self-holding relay RO ₁ , the interlock relay R ₁ , the starting magnet operating coil S ₁ , the series connection circuit of the contact 45 ₁ and the timer circuit DT ₁ are normally closed. The interlock relays R ₁ are connected in parallel via a certain contact point 43 ₁ (b contact point), and when the power is supplied, the contact point r ₁ changes the contact point r ₁ from the closed state to the open state. By the operation of the relay R ₁ , the conduction state of the interlock circuit 26 ₁ is maintained, but the interlock circuit 2 of the other motor M _k is maintained.
The 6 _k is configured to be in the cutoff state.

[0036] When the illustrating an example of the operation of the motor starting device 2 of the present invention as an example when starting with the motor M ₁ Manual, advance the respective changeover switch SW ₁
~ SW _n is switched to the manual side, and next, in order to select the motor M ₁ from the plurality of motors M _{1 to} M _n ,
The manual on-switch PSW ₁ is pressed to turn it on.

Since the other end of the relay RO ₁ is connected to the power source by a contact 44 ₁ (contact b) which is normally closed, the contact 44 ₁ and the on switch PS for manual operation are connected.
W _1, the off switch 24 _1, and by the route of the interlock circuit 26 _1, the electric power is supplied from the self-holding the AC power supply 31 to the relay RO ₁ is operating, the self-holding contact 22 ₁ closed state To Then, since the manual on-switch PSW ₁ is bypassed, even if the manual on-switch PSW ₁ is turned off,
Unless the OFF switch 24 ₁ is opened, the self-holding relay RO ₁ is supplied with power, and as a result,
The self-holding contact 22 ₁ continues to maintain a closed state, and the conductive state of the self-holding circuit 21 ₁ is also held.

At this time, the self-holding relay RO ₁ includes an interlock relay R ₁ for controlling the open / closed state of the interlock circuits 26 _{2 to} 26 _n and a starting magnet operating coil S ₁ for opening / closing the starting magnet switch S _{1. Since 1} and ₁ are connected in parallel through the normally closed contact 43 ₁ (b contact), power is also supplied to the interlock relay R ₁ and the starting magnet operating coil S _1. At the same time that the self-holding relay RO ₁ operates, the interlock relay R ₁ and the starting magnet operating coil S ₁ operate.

By the operation of the interlock relay R ₁ , the n−1 contacts r _{1 in the} interlock circuits 26 _{2 to} 26 _n are opened, so that the motors other than the motor M ₁ cannot be started. , Thereby preventing double starting. Further, the interlock relay R ₁ closes the contact r ₁ and simultaneously closes the contacts 48 ₁ and 50 ₁ to prepare for starting the starting magnet operating coil S ₁ .

On the other hand, the starting magnet operating coil S ₁
By this operation, the starting magnet switch S ₁ is closed and the contact 45 ₁ is changed from the open state to the closed state. At this time, the starting magnet operating coil S ₁ and the interlock relay R ₁ connected in parallel are connected.
Further, since a timer circuit DT ₁ is connected in parallel via the contact 45 ₁ , the timer circuit DT ₁ is also supplied with power via the contact 45 ₁ . The timer circuit DT ₁ starts its operation by the supply of this electric power, and after the elapse of a certain time, the contact 47 ₁ is closed so that the main starting magnet operating coil A is supplied with electric power. The magnet switch A changes from the open state to the closed state after the starting magnet switch S ₁ is in the closed state and after the elapse of the predetermined time defined by the timer circuit DT ₁ , and the thyristor reverse connection is made. The switch 4 will be connected to the three-phase AC power supply.

Since the main starting magnet operating coil A changes both the contact 47 ₁ and the contact 54 to the closed state, the electronic starter CSS causes the AC power supply 31 to operate.
It is connected to and becomes operational.

At this time, the starting magnet switch S
_{Since 1} is in a closed state, when each thyristor is placed in a conductive state, the motor M ₁ operates as follows: the thyristor reverse connection switch 4, the starting magnet switch S ₁ ,
With the main starting magnet switch A,
It is connected to the phase alternating current power supply (RST) and power is supplied.

However, the electronic starter CSS is set so as to gradually reduce the size of the period during which each of the thyristors 11 _{1 to} 11 ₆ is in the shut-off state. Therefore, each of the thyristors 11 ₁ to 11 ₁ Since the period during which 11 ₆ conducts gradually increases and the average voltage applied to the motor M ₁ gradually increases, the inrush current immediately after the start is prevented and the soft start of the motor M ₁ is performed. FIG. 4 shows an example of such a control method. In this example, to facilitate understanding, it is assumed that the thyristor is fired after an angle α from the point where the voltage applied across the thyristor is zero, and the arc is extinguished when the voltage applied to the thyristor becomes zero. Then, the angle α is gradually decreased, and the period of the conductive state is gradually increased to achieve the soft start.
However, since the motor is an inductive load and there is a difference between the phase of voltage and the phase of current, the current actually becomes zero before the voltage applied to the thyristor becomes zero, and the thyristor It is normal to extinguish the arc.

[0044] Such a soft start is performed, a period in the cutoff state is zero, become power supply voltage to the motor M ₁ and the entire period becomes conductive is applied as it is applied to the motor M ₁ The applied voltage has the maximum value. After this time, the motor M ₁ is in the rated operation state, and the flowing current is also the actual load current of the motor M ₁ .

When the starting operation of the motor M ₁ is completed by the electronic starter CSS in this manner, the contact 49 is closed by the electronic starter CSS. At this time, since the contacts 48 ₁ and 50 ₁ are already closed by the operation of the interlock relay R ₁ , the driving magnet operation coil B ₁ is connected to the operation magnet operation coil B ₁ via the interlock circuit 26 _1. Contact points 48 ₁ , 49, 50
Power is supplied by the _first path, the said driving magnet Coil B ₁ is to a closed state operating magnet switch B ₁ is operated, the starter magnet switch S ₁ and the driving magnet switch B ₁ are both closed Because it will be in a state,
The motor M ₁ is operated in the overlap state.

The operating magnet operating coil B ₁
Causes the magnetic switch B ₁ to be closed and the contact 51 ₁ to be closed, so that the contact 51 ₁ forms a bypass of the power supply path of the contacts 48 ₁ , 49 and 50 ₁ . Electric power is supplied to the operating magnet operating coil B ₁ itself through the contact 51 ₁ . Therefore, the driving magnet (operating coil) B ₁ forms a self-sustaining circuit.

By the way, the electronic starter CSS has a built-in timer (overlap circuit), and the electronic starter CSS opens the contact 49 after a lapse of a predetermined overlap period τ. Contacts 48 ₁ and 4
The current supply path of 9, 50 ₁ to the operating magnet operating coil B ₁ is cut off, and the operation of the thyristor antiparallel connection switch 4 is stopped. The contact 51 ₁ is closed state, since the electric power to the driving magnet operating coil B ₁ via the said contact 51 ₁ is continuously supplied, thereafter supply power to the motor M ₁ from the driving magnet switch B ₁ To be done.

Further, the operating magnet operating coil B ₁
By the operation, the contacts 46 _1, since it is with the contact 51 ₁ in the closed state, said contact 46 _1, the second timer circuit and power is supplied to the DTA _1, said timer circuit DTA ₁ is the The timer circuit DTA has been in operation since the beginning of the overlap period τ.
₁ causes the contact 43 ₁ to be opened after a lapse of a predetermined time from the overlap period τ, whereby the power supplied to the starting magnet operating coil S ₁ is stopped and the operation is completed. , The starting magnet switch S ₁ that was in the closed state even after the end of the overlap period is returned to the open state, and the thyristor reverse connection circuit 4 is disconnected from the motor M ₁ .

When the contact 43 ₁ is opened, the interlock relay R ₁ and the timer circuit DT ₁ are released.
Since the power supply to the terminals is also stopped, the contacts 48 ₁ , 50 ₁ , 47 ₁ which have been closed by these are returned to the open state. The operation of the main starting magnet operating coil A is completed by opening the contact 47 ₁ .
Upon completion thereof, the contact 54 is opened, and the supply of electric power to the electronic starter CSS is stopped.
The operation of the electronic starter CSS is also completed, and the other desired motor M _k can be started.

However, even when the contacts 48 ₁ and 50 ₁ are opened, the contact 51 ₁ is maintained in the closed state, whereby the operation of the operating magnet operating coil B ₁ is self-held. The rated operation state of the motor M ₁ is continued.

Further, since the timer circuit DTA ₁ opens the contact 43 ₁ and simultaneously closes the contact 42 ₁ , the contact 42 ₁ allows the operation magnet operating coil B ₁ and the operation magnet operating coil B ₁ to be closed. Since the bypass of the interlock circuit 26 ₁ which was a power supply path to the relay RO ₁ is formed and the self-holding contact 22 ₁ maintains the closed state, motors other than the motor M ₁ are started. , The operation of the operating magnet operating coil B ₁ is maintained even when _one of the contacts r _k (here, 2 ≦ k ≦ n) forming the interlock circuit 26 ₁ of the motor M ₁ is opened. Therefore, the off switch 2
Unless 4 ₁ is opened, the rated operating state of the motor M ₁ is maintained.

The operation state of each switch, each contact point, each circuit, and each magnet when starting the above-mentioned motor M ₁ is summarized in the timing chart of FIG. When the power is supplied or the contact is closed,
gh), the state in which the power supply is stopped or the open state is represented by Low. Therefore, the a-contact is shown low in the normal state and the b-contact is shown high in the normal state.

The timer circuit D connected in series
An overcurrent detector EOCR ₁ is connected in parallel to TA ₁ and the contact 46 ₁ , and when electric power is supplied to the overcurrent detector EOCR ₁ , the motor M ₁
When the overcurrent of the motor M ₁ is detected and the overcurrent of the motor M ₁ is detected, the contact 44 ₁ which is normally closed is opened, and the operation of the motor M ₁ is stopped. Oru. Therefore, there is no possibility that _one motor fails and the starting device 2 is destroyed, and the other motors cannot be started (however, this overcurrent detector EOCR ₁ is not always necessary).

Here, the magnitude of the current flowing through the motor M ₁ is overlapped with the timings of the starting magnet switch S ₁ and the operating magnet switch B ₁ in FIG. 6 (a).
~ (C) and (f) of the same figure.

FIGS. 7A and 7B show the operation of the thyristor antiparallel connection switch and the operation of the operating magnet switch B ₁ , respectively, and FIG. 7C is a timing chart showing the overlap period τ. is there.

FIG. 6 (f) is a timing chart showing the magnitude of the current flowing through the motor M _{1. The} period during which the thyristor is in the conducting state is gradually increased and the soft start is performed. The state is shown in which the overlap period is set to start after the current has started to flow.

Incidentally, FIGS. 7D and 7E are diagrams for explaining the operation of an error circuit (not shown in FIGS. 1 and 2) provided inside the electronic starter CSS. Is. This error circuit is a circuit that operates when the start control circuit of the electronic starter CSS has a failure and when it fails during start-up, and the internal relay that supplies a DC voltage to the start control circuit is opened. When the operation of the start control circuit is stopped, the error control circuit simultaneously receives a DC signal.
Voltage is supplied, and after a predetermined error time ε (about 1 second) elapses by the timer inside the electronic starter CSS.
((E) in the same figure), the operating magnet switch B ₁ is immediately closed while outputting a signal ((d) in the same figure).

However, since the DC voltage is not supplied to this error circuit when the start control circuit is operating normally, the operating magnet switch B ₁ operates after the completion of startup when normal, and when it fails, the error circuit operates by the error circuit. It will work.

When the motor M ₁ is started as described above, if the manual on-switch PSW _k of the motor M _k to be started next is pushed to bring it into conduction, it is as if the motor M ₁ was started. By the same operation, the motor _Mk is soft-started. Further, when the desired motor M _k in the rated operating state is desired to be stopped, the off switch 24 _k of the motor may be opened, and when it is desired to be started again, the manual on-switch P of the motor is required.
It suffices to turn on SW _k . In this way, a desired motor can be started / stopped intermittently.

The states of the contacts r _{1 to} r _n when the motors are operating are summarized in Table 1 below.

[0061]

[Table 1]

Although the starting of the motor M ₁ has been described above, it does not mean that a plurality of motors are started in order from the motor M _1, and it goes without saying that any motor can be started in a desired order.

In the above description, the case of switching to the manual side has been described. However, the changeover switches SW _{1 to} SW _n are switched to the remote side and the remote switches 25 _{1 to} 25 _{n are changed.}
A sequencer in which the sequence of operation of starting, stopping, and restarting each motor is stored in is connected to each of the remote switches 25 ₁ to 2 in accordance with the sequence of operation stored in the sequencer.
By controlling the closed and open states of 5 _n ,
It is possible to automatically start / stop / restart each of the motors, thereby enabling a plurality of motors to be operated intermittently.

Such an embodiment of the present invention will be described by taking as an example the case where the _three motors M _{1 to} M ₃ are operated intermittently. Referring to FIG. 7, reference numeral 12 is a motor starting device in which the sequencer 7 and the timer 8 are provided in the motor starting device 2 of the above-described embodiment, and the three motors M _{1 to} M ₃ are the same as those in the above-described embodiment. , Connected to be soft-started.

The changeover switches SW _{1 to} SW ₃ are set on the remote side, and the sequencer 7 turns on / off the remote switches 25 _{1 to} 25 ₃ in accordance with the operation sequence stored in advance based on the signal of the timer 8. Let me turn it off
The motors M _{1 to} M ₃ are configured to start, stop, and restart.

The operation sequence will be described with reference to FIG.
First, the sequencer 7 first operates the remote switch 2
Turn on 5 ₁ . Then, electric power is supplied to the starting magnet operating coil S ₁ , and the starting magnet switch S ₁ is closed. At this time, when power is also supplied to the interlock relay R ₁ to start the operation, the contact r ₁ in the interlock circuits 26 ₂ and 26 ₃ is opened to prohibit the start of other motors. It

Then, the main starting magnet switch A is closed and the motor M1 is connected to the power source, and the period during which the thyristor antiparallel connection switch 4 is conducting is gradually increased so that the motor M ₁ Soft start is started (time X ₁ ).

After a lapse of a predetermined time, the operating magnet switch B ₁ is closed, and the operating magnet switch B ₁ and the thyristor antiparallel connection switch 4 are operated in parallel for the overlap period τ. When the operation of the interlock relay R ₁ is completed, the starting magnet switch S ₁ and the main starting magnet switch A are opened, and the thyristor reverse connection circuit 4 is disconnected from the motor M ₁ . In this state, the start of the motor M ₁ is completed, and the rated operation is performed by the operating magnet B ₁ .

Next, the motor M ₂ is started, and the sequencer 7 is set so that the remote switch 25 ₂ is immediately turned on when the operation of the interlock relay R ₁ is completed. When the relay is turned on, the interlock relay R ₂ starts to operate, the main starting magnet switch A and the starting magnet switch S ₂ are closed, the motor M ₂ is connected to a power source, and the thyristor antiparallel connection is made. The period during which the switch 4 is conductive is gradually increased, and the soft start of the motor M ₂ is started (time X ₂ ). When the soft start is completed, the operating magnet switch B ₂ is closed, and the operating magnet switch B ₂ and the thyristor anti-parallel connection switch 4 are operated in parallel for the overlap period τ, and then the operating magnet. The switch S ₂ and the main starting magnet switch A are opened, the rated operation of the motor M ₂ is performed by the operation magnet switch B ₂ , and the operation of the interlock relay R ₂ ends.

Next, the motor M ₃ is started, and the sequencer 7 is set to turn on the remote switch 25 ₃ immediately after the operation of the interlock relay R ₂ is completed. _{For 3} , the soft start is started like the motors M ₁ and M _2.
(Time X ₃ ), after parallel operation, the rated operation is performed by the operating magnet B ₃ , and thus the rated operation of each of the motors M _{1 to} M ₃ is performed.

When each of the motors M _{1 to} M ₃ has been rated for a predetermined time, the sequencer 7 first turns off the remote switch 25 ₂ to stop the operation of the motor M ₂ (time X ₄ ). Next, when the remote switches 25 ₁ and 25 ₃ are turned off to stop the operation of the motors M ₁ and M ₂ (time X ₅ ), the motors M _{1 to} M ₃ are
The first cycle of operation ends.

After the operation of the first cycle is completed and a predetermined time determined by the timer 8 has elapsed, the sequencer 7 soft-starts each of the motors M _{1 to} M ₃ as in the first cycle ( Time X _{11 to} X ₁₃ ),
After the rated operation is performed for a predetermined time, the motor M ₂
There is stopped (time X _14), then the motor M _1, M ₃ is stopped (time X _14, X _14), operation of the second cycle is completed thus.

Continuing, the third cycle, the fourth cycle ...
, And each of the motors M _{1 to} M ₃ are operated for a desired number of cycles. If such a cycle-by-cycle operation is performed in a production line, for example, one finished product can be obtained for each cycle operation of the motors M _{1 to} M ₃ ,
The sequencer 7 allows the motors M _{1 to} M ₃ to be operated intermittently to construct an automatic production line.

By the way, in the timing chart shown in FIG. 8, a signal for turning on the remote switches 25 _{1 to} 25 ₃ at the same time is not input, and a normal signal is input to the motor starter 12. Has been done.

However, if there is a setting mistake in the sequencer 7 or noise invades, malfunctions may occur in which the remote switches 25 _{1 to} 25 ₃ are simultaneously turned on.

As an example of when such a malfunction occurs, the motor starter 12 when the remote switch 25 ₂ is turned on during the start of the motor M _1.
The operation will be described with reference to the timing chart of FIG.

Referring to FIG. 9, first, the remote switch 25 ₁ is turned on and the interlock relay R ₁ is turned on.
Is operated, the starting magnet switch S ₁ and the main starting magnet switch A are closed, and the soft start of the motor M1 is started.
(Time Y ₁ ).

It is assumed that the sequencer 7 turns on the remote switch 25 ₂ during the soft start of the motor M ₁ in which the conduction period of the thyristor antiparallel connection switch 4 is gradually increased (time E ₁ ). . In this state, the interlock circuit R ₁ is in the operating state, the contact r ₁ in the interlock circuit 26 ₂ is in the open state,
Therefore, even if the remote switch 25 ₂ is turned on, the electric power is not supplied to the starting magnet operating coil S ₂ , so that the motor M ₂ is not started and the interlock relay R ₂ also operates. do not do.

The operation of the interlock relay R ₂ is started when the operation of the interlock relay R ₁ is finished and power is supplied to the interlock relay R _2. Yes, after a lapse of a predetermined time from the start of the operation of the interlock relay R ₂ , the starting magnet switch S ₂ and the main starting magnet switch A are closed, and the motor M ₂
Soft start is started (time Y ₂ ).

As described above, the remote switch 25 ₂
Even when the switch is turned on, from that time until the operation of the interlock relay R ₁ ends (time δ)
Does not start the starting operation of the motor M ₂ . In the case of FIG. 9, the time when the soft start of the motor M ₁ ~M ₃ is started (time Y ₁ to Y ₃₎ is started the soft start of each motor M ₁ ~M ₃ in the case of FIG. 8 It is the same time as the time (time X _{1 to} X ₃ ) to be performed.

Then, the interlock relay R ₂
When the above operation is completed, the remote switch 25 ₃ is turned on by the sequencer 7, and the soft start of the motor M ₃ is started (time Y ₃ ) similarly to the operation in FIG.

After the motors M _{1 to} M ₃ have been rated for a predetermined time, the motor M ₃ is first stopped (time Y ₄ ), and then the operations of the motors M ₁ and M ₂ are stopped.
(Time Y ₅ ), and thus the operation of the first cycle ends.

When the operation of the first cycle is completed and a predetermined time has elapsed, the restart of the motor M ₁ is started. In this case, similar to the operation of the first cycle, the remote switch 25 ₂ is turned on during the operation of the interlock relay R ₁ (time E ₂ ), but the motor M ₂ does not operate the interlock. The starting operation cannot be started until the operation of the relay for motor R ₁ is completed, and the motor M ₁
~M ₃ is soft start is started at the same timing as the first cycle.

In this way, the motors M _{1 to} M ₃ are started / stopped / restarted. However, since the interlock circuits 26 _{1 to} 26 _n work effectively, the other motors are started while one motor is being started. Even when the remote switch of the motor is turned on, the start of the motor is not started, and a plurality of motors are not started at the same time and a large current flows from the power source.

It should be noted that the sequencer of the present invention is only required to be capable of storing the operation sequence and closing each of the starting magnet switches in accordance with the sequence, and includes various devices such as a computer control device.

Further, in the above embodiment, the conducting period of the thyristor is gradually lengthened to increase the average voltage applied to the motor, but the present invention is not limited to this and the voltage applied to the motor is not limited thereto. Any thyristor control method that can gradually increase the average voltage can be applied.

[0087]

EFFECTS OF THE INVENTION Since each motor is soft-started, inrush current does not flow immediately after starting, and arc discharge does not occur when the contacts of the sequence relay are opened and closed. When starting or restarting multiple motors in the desired order, multiple motors do not start at the same time even if there is a mistake in the sequencer's input or superimposition of noise, so a large current does not flow and there is an excessive capacity. There is no need to use the power source or power transmission line.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining an example of an embodiment of the present invention.

FIG. 2 is an example of a block diagram of an internal circuit of a motor starter of the present invention.

FIG. 3 Internal structure diagram of thyristor antiparallel connection switch

FIG. 4 is a diagram for explaining an example of a thyristor control method.

FIG. 5 is a timing chart for explaining the operation of the motor starter of the present invention.

6A is a timing chart showing the operation of the thyristor anti-parallel switch, FIG. 6B is a timing chart showing the operation of the operating magnet switch, FIG. 6C is a timing chart showing the overlap period, and FIG. 6D is a diagram showing the operation of the overcurrent detection circuit. Timing chart (e) Timing chart showing error time (f) Timing chart showing magnitude of current flowing in motor

FIG. 7 is a block diagram for explaining another example of the embodiment of the present invention.

FIG. 8 is a timing chart for explaining the operation.

FIG. 9 is a timing chart for explaining an operation when an abnormal input is made.

10A is a block diagram of a conventional Y-.DELTA. Type motor starting device. FIG. 10B is a circuit diagram showing a case where the motor starting device is Y-connected. FIG. 10C is a Δ-connection of the motor starting device. Circuit diagram showing the case

FIG. 11 is a diagram showing a current change in a conventional Y-Δ starting method.

[Explanation of symbols]

4 ...... thyristor reverse parallel-connected switches 7 ...... sequencer 26 ₁ ~ 26 _n ...... interlock circuit B ₁ .about.B _n ...... driving magnet switch M ₁ ~M _n ......
Motors S _{1 to} S _n …… Starting magnet switch (RST) …… Power supply τ …… Overlap period The symbols used in Figures 1 to 4 are shown below. (1) Symbols used in Fig. 2 …… Motor starter 4 …… Thyristor anti-parallel connection switch (RST) …… (3-phase) power supply CSS …… Electronic starter M _{1 to} M _n …… Motor A… … Main start magnet switch B _{1 to} B _n …… Running magnet switch S _{1 to} S _n …… Start magnet switch (2) Symbol used in FIG. 2 CSS …… Electronic starter M _{1 to} M _n …… Motor A …… Main start magnet operation coil B _{1 to} B _n …… Running magnet operation coil S _{1 to} S _n …… Start magnet operation coil SW _{1 to} SW _n …… Changeover switch (remote / off / manual) PSW _{1 to} PSW _n ...... manual for on switch (selecting means) DT ₁ to DT _n ...... timer circuit DTA ₁ ~DTA _n ...... timer circuit RO ₁ ~RO _n ...... self-holding relay EOCR ₁ ~EOCR _n ...... overcurrent detection Vessel R ₁ ~R _n ...... interlock relay r ₁ ~r _n ...... interlock relay R ₁ to R _n of b contact 22 ₁ ~22 _n ...... self-hold circuit relay RO ₁ ~RO _n of a contact 24 ₁ ~24 _n ...... off switch 25 ₁ ~25 _n ...... remote switch 26 ₁ ~26 _n ...... interlock circuit 42 ₁ ~42 _n ...... timer DTA ₁ ~ timer DTA _n of a contact 43 _{1-43 n} ...... timer DTA ₁ ~ b-contact 44 ₁ ~ 44 _n timer DTA _n ...... overcurrent detector EOCR ₁ ~EOCR _n of b contact 45 ₁ ~45 _n ...... starting magnet S ₁ to S _n of a contact 46 _{1 ~46 n} ...... driving magnet B ₁ .about.B _n of a contact 47 ₁ ~47 _n ...... timer DT ₁ to DT _n of a contact 48 ₁ ~48 _n ...... interlock relay R ₁ to R _n of a
Contact 49: a contact of electronic starter CSS 50 ₁ to 50 _{n: a of} interlock relays R _{1 to} R _n
Contacts 51 _{1 to} 51 _n ...... contact a of operating magnets B _{1 to} B _n (3) Symbols used in Figs. 3 to 4 4 thyristor antiparallel connection switch 11 _{1 to} 11 ₆ thyristors R, S, T: Each phase of 3-phase power supply α: Phase control angle (switch) A: Main starting magnet switch A (coil) A: Main starting magnet operating coil A (switch) S ₁ ... Starting magnet switch S ₁ (Coil) S ₁ …… Starting magnet operating coil S ₁ (Switch) B ₁ …… Running magnet switch B ₁ (Coil) B ₁ …… Running magnet operating coil B ₁

Claims (2)

[Claims] 1. A motor starting device for starting a plurality of motors, the operating magnet switches being provided according to the number of the motors, each operating a motor switch for connecting each motor to a power source, and each operating magnet switch connected in parallel. A starting magnet switch, a thyristor anti-parallel connection switch inserted between each of the starting magnet switches and the power supply, and one of the plurality of starting magnet switches when the starting magnet switch is closed. It has an interlock circuit that maintains the open state of the other start magnet switch while it is started and its start magnet switch is in the closed state, and the start magnet switch provided in one motor is in the closed state. To bring the thyristor antiparallel connection switch into a conductive state, and By gradually increasing the voltage applied to the motor by controlling the thyristor anti-parallel connection switch, after all the thyristor anti-parallel connection switch is turned on,
After the operation magnet switch is closed and a predetermined overlap period has elapsed, the thyristor anti-parallel connection switch is turned off, the start magnet switch is opened, and the motor is operated at the rated operation by the operation magnet switch. A motor starting device for putting into a state, wherein the starting of the other motor is not started by the operation of the interlock until the starting of the one motor is completed. 2. A sequencer in which an operation sequence for starting and restarting the plurality of motors is stored is provided, and the sequencer closes each of the starting magnet switches in accordance with the operation sequence, and the plurality of motors are closed. Is a motor starting device configured to automatically start and restart the device, wherein two or more of the starting magnet switches are erroneously closed by the operation of the interlock circuit. The motor starter according to claim 1, wherein the motor starter is prevented.