JPH02276485A - Starting device for cage type induction motor - Google Patents

Abstract

PURPOSE:To reduce the power supply capacity of a generator and the like by restraining the generation of a starting peak current by the generator of starting voltage commanding pattern or the like. CONSTITUTION:The starting device of a cage type induction motor 1, employing a thyristor 15, is provided with a starting initial period voltage setter 9, an initial period voltage continuing time setter 10, a voltage increasing rate setter 11, a load current limit value setter 12, a limit signal generator 13 and a control unit 5. The control unit 5 is provided with a function generator 14, generating a starting voltage commanding pattern, in order to give the primary voltage of the motor 1 a desired starting voltage impressing pattern. As a result, the primary voltage is changed from a small starting initial period voltage with a specified increasing rate and, therefore, a starting peak current will never become big.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a starting device for a squirrel-cage induction motor, and more specifically to a starting control device for controlling the primary voltage of a squirrel-cage induction motor using a thyristor. , the starting voltage command pattern can be arbitrarily selected, thereby suppressing the starting peak current by changing the starting voltage, and also suppressing short-term overheating of the generator engine while the motor is starting and the generator receiving power from it. The present invention relates to a starting device for a squirrel cage induction motor that can avoid exceeding the load capacity.

[Conventional technology]

When a direct start method is used for a large induction motor, a large starting peak current of 6 to 8 times the rated current flows. Therefore, after reducing the applied voltage during starting using the starting compensator method or star-triangle starting method, the full voltage is applied after the motor rotation speed has increased to bring it into normal operating condition, thereby suppressing the starting peak current. It is common practice to do so. On the other hand, in a system where power is supplied from a diesel generator for private power generation to several squirrel-cage induction motors, if a voltage drop occurs in the generator due to the generation of a large starting peak current, the rotational speed of the motor that is already in operation will decrease. A temporary drop may cause inconvenience.

In order to eliminate this phenomenon, the present applicant filed a patent application filed in 1983.
No. 3-83658 proposes a starting device in which a starting voltage command pattern is generated by a function generator, and the trigger signal is used to apply a primary voltage that becomes the starting voltage application pattern to a squirrel cage induction motor using a thyristor. did. According to this, in order to suppress the voltage drop during starting of a squirrel cage induction motor within an allowable range, it is not necessary to select a diesel generator with a capacity considerably larger than the total load capacity for continuous operation, and All that is required is to install power generation equipment with a capacity slightly larger than that required. Of course, the same applies when power is being supplied from a power receiving transformer, making it possible to downsize and reduce the cost of equipment.Also, even when adding a new motor to the power supply, the power supply capacity based on the starting current can be reduced. No need to change.

[Problem to be solved by the invention]

The above-mentioned starting device uses a thyristor, which is widely used for controlling the primary voltage of an electric motor, and
Although not described in detail here, an initial starting voltage setting device for setting the initial value of the starting voltage and a voltage increase rate setting device for setting the rising rate of the starting voltage from the initial value are provided. The motor is equipped with a function generator that generates a starting voltage command pattern for making the primary voltage applied to the squirrel cage induction motor into a desired starting voltage application pattern by synthesizing command signals corresponding to the respective set values. According to this, the control of the primary voltage by the thyristor can be set to match the load of the motor.

By the way, when the power source is a generator using an engine such as a diesel generator, the short-term overload capacity of the engine is, for example, 100 to 130% of the rated value, 15 seconds, and the short-term overload capacity of the generator is, for example, 15 seconds, which is 100 to 130% of the rated value. It is said to be 150% of 15 seconds. These values often differ depending on the application and manufacturer.

On the other hand, with the above-mentioned starting device that is equipped with a function generator and controls the primary voltage with a thyristor, the rising slope of the voltage can be set freely, but if a steep rising slope is selected with the intention of completing the start quickly, the engine Alternatively, one or both of the generators may exceed their overload capacity for a short period of time, causing problems such as a decrease in engine speed and overheating of the generator. In order to avoid this, if the engine capacity or generator capacity is increased, the value of the starting device will decrease and it will become uneconomical.

The present invention was made in view of the above-mentioned problems, and its purpose is to suppress the generation of starting peak current when starting a squirrel-cage induction motor, so that when a generator is provided, the capacity of the generator is reduced to a power receiving transformer. In the case where power is supplied from
It is possible to easily adjust the starting voltage according to the starting torque required by the motor load, and it is also possible to start a squirrel cage induction motor within the short-term overload capacity of the engine or generator, which varies depending on the model. An object of the present invention is to provide a starting device for a squirrel-cage induction motor that prevents overheating of a generator and reduction of rotational speed of an engine.

In particular, it is possible to easily change the starting voltage command pattern each time to obtain a starting voltage application pattern commensurate with the load current or power value at the time of starting the squirrel cage induction motor, taking into account the short-term overload capability of the engine and generator. , its main purpose is to be able to protect power supply equipment.

[Means to solve the problem]

The present invention is applied to a starting device for an induction motor that uses a thyristor to control the primary voltage of a squirrel cage induction motor. Its characteristics are as shown in Figure 1.
An initial starting voltage setting device 9 that sets the initial value of the starting voltage, a voltage increase rate setting device 11 that sets the rate of increase of the starting voltage from the initial value, and a load current that sets the load current limit value of the squirrel cage induction motor 1. In order to set the primary voltage applied to the squirrel cage induction motor 1 to a desired starting voltage application pattern by combining command signals according to the set values by the limit value setting device 12, starting initial voltage setting device 9, and voltage increase rate setting device 11. The function generator 14 that generates the starting voltage command pattern determines whether the load current of the squirrel cage induction motor 1 exceeds the load current limit value set by the load current limit value setting device 12, and if it exceeds the load current limit value set by the load current limit value setting device 12, A restriction that outputs to the function generator 14 a limit signal that holds the voltage increase command signal of the starting voltage command pattern generated by the function generator 14 until the load current of the squirrel cage induction motor l becomes equal to or less than the load current limit value. A configuration comprising a signal generator 13 and a gate control circuit 16 that causes a thyristor 15 to apply a primary voltage serving as a starting voltage application pattern to the squirrel cage induction motor 1 using a trigger signal based on a starting voltage command pattern in the function generator 14 of the signal generator 13. This is what happened.

In addition to the starting initial voltage setting device 9, the voltage increase rate setting device 11, the load current limit value setting device 12, the limit signal generator 13, and the gate control circuit 16, an initial voltage that sets the time for which the starting initial voltage continues is also provided. The primary voltage to be applied to the squirrel cage induction motor l is determined by combining the command signals according to the settings of the duration setting device 10, the starting initial voltage setting device 9, the initial voltage duration setting device lO, and the voltage increase rate setting device 11. This configuration includes a function generator 14 that generates a starting voltage command pattern to obtain a desired starting voltage application pattern.

On the other hand, instead of the load current of the squirrel cage induction motor 1,
The features of the device that temporarily holds the voltage increase command signal based on the electric power value of the electric motor are as follows with reference to Fig. 2.
An initial starting voltage setting device 9 that sets the initial value of the starting voltage, a voltage increase rate setting device 11 that sets the rate of increase in the starting voltage from the above-mentioned initial value, and a power limiter that sets the power limit value of the squirrel cage induction motor 1. By combining command signals according to the set values by the value setter 19, starting initial voltage setting device 9, and voltage increase rate setting device 11, the primary voltage applied to the squirrel cage induction motor 1 is set to a desired starting voltage application pattern. Function generator 14 that generates a starting voltage command pattern, squirrel cage induction motor 1
The power value calculator 20 calculates the power value of the power value calculator 20, and the power value inputted from the power value calculator 20
It is determined whether the power limit value set in is exceeded, and if the power value exceeds the power limit value set by A limit signal generator 21 that outputs a limit signal to the function generator 14 to be held until the value becomes equal to or less than the value.
, the structure includes a gate control circuit 16 that causes a thyristor 15 to apply a primary voltage that becomes a starting voltage application pattern to the squirrel cage induction motor l using a trigger signal based on a starting voltage command pattern in the function generator 14. .

In addition to the starting initial voltage setting device 9, voltage increase rate setting device 11, power limit value setting device 19, power value calculator 20, limit signal generator 21, and gate control circuit 16, the time period during which the starting initial voltage continues Squirrel cage induction motor 1 A function generator 14 is provided for generating a starting voltage command pattern for making the primary voltage applied to a desired starting voltage application pattern.

[For production]

When setting is performed using the starting initial voltage setting device 9 and the voltage increase rate setting device 11, the function generator 14 is activated based on the set values.
Now, a starting voltage command pattern is generated by combining each command signal. According to this starting voltage command pattern, a trigger signal is output from the gate control circuit 16 to the gate of the thyristor 15, and the thyristor 15 applies the primary voltage of the desired starting voltage application pattern to the motor 1 in response to the signal.

Since the primary voltage changes at a specified rate of increase from the initial starting voltage, which is lower than in the direct-on starting method, the starting peak current does not increase and the current necessary to start the load can be generated. If the inertia is large and starting torque is required and it takes time to start, change the setting value of the initial starting voltage setting device 9 or voltage increase rate setting device 11 to increase the voltage over a longer or shorter time. You can also do it.

When starting with a starting voltage application pattern based on the starting voltage command pattern, the load current of the squirrel cage induction motor 1 is detected, and the load current limit set by the load current limit value setting device 12 is set. When the value is exceeded, a limit signal is output from the limit signal generator 13 to the function generator 14. The increase in the starting voltage is stopped, and controlled so as not to exceed the short-term overload capacity of the power generator, for example. When the load current falls below the set value, the limiting signal is not output, and the primary voltage that is increased at the original voltage increase rate is applied to the motor 1.

If the initial voltage duration setting device 10 is provided, the starting voltage command in the function generator 14 will be a pattern in which the initial starting voltage is maintained for a certain period of time, and the starting voltage application pattern can be changed according to the magnitude of the inertia of the load. It becomes even easier.

If the power value of the squirrel cage induction motor 1 exceeds the value set by the power limit value setter 19 instead of the load current described above, a function generator is output from the limit signal generator 21 in the same manner as in the above case. A limit signal is input to 14, and a starting voltage command pattern is set that suppresses an increase in starting voltage. As a result, the squirrel-cage induction motor 1 is started with the primary voltage applied from the thyristor 15 so as not to exceed the short-term overload capability of the power generation equipment.

Even when such a starting method is adopted, if an initial voltage duration setting device 1O is provided, it becomes easier to change the starting voltage command pattern generated by the function generator 14 according to the application.

〔Effect of the invention〕

According to the present invention, the starting voltage is gradually increased from the initial voltage within a range that does not cause any problem in starting the load, and the generation of a large starting peak current in the squirrel cage induction motor is suppressed, thereby enabling soft starting. Therefore, the capacity of the power generation engine and the capacity of the generator or power receiving transformer can be small, and in such a case, no shock is given to the load at the time of startup. At that time, the rise in starting voltage is suppressed within the range of the load current limit value and power limit value set so as not to exceed the short-term overload capacity of the generator and engine, preventing generator overheating and engine rotation speed. Deterioration etc. are avoided. If an initial voltage duration setting device is also adopted to synthesize the starting voltage command pattern generated by the function generator, the degree of freedom for the initial adjustment of the starting voltage command pattern will be greater. A wide range of starting methods can be selected to suit the various loads being applied.Furthermore, the starting device is a stationary type, significantly reducing maintenance and inspection effort, resulting in a smaller and lighter device. .

If the initial voltage duration setting device is not provided, the device can be made with fewer configurations and is even cheaper.

〔Example〕

The starting device for a squirrel cage induction motor according to the present invention will be explained in detail below.

Figure 3 is a standard circuit diagram for feeding power to and driving a squirrel cage induction motor 1. Normally, power supplies R, S, and T each have a circuit breaker 2, an electromagnetic contactor 3, and a thermal relay 4, and control A control unit 5 is connected thereto. A switch 6 for commanding start and stop, and an indicator light 7
and a signal light 8 are provided. Above control unit 5
For example, a total of four small volume resistors 9 and 10.11°12 are attached to the unit, and these are used to set the starting initial voltage, initial voltage duration time, voltage increase rate setting, and load current limit value, respectively. Functions as a vessel. Furthermore, it is determined whether the load current of the squirrel cage induction motor 1 during starting exceeds the load current limit value set by the small volume type resistor 12, and if it exceeds the load current limit value, the control unit 5, which will be described next, is applied to limit the load current. Limit signal generator 1 that outputs a signal
3 is provided.

FIG. 1 is a block diagram of the overall configuration of the starting device shown together with a schematic system diagram. 5 in the figure indicates each of the above setting devices 9.
10. Upon receiving the setting command in 11, the limit signal from the limit signal generator 13 is sent until the load current of the squirrel cage induction motor l becomes equal to or less than the load current limit value set by the load current limit value setter 12. This is a control unit that receives the trigger pulse and outputs a trigger pulse to the thyristor 15. The control unit 5 comprises a function generator 14 and a known gate control circuit 16.

The above-mentioned initial starting voltage setting device 9 specifies the initial value of the starting voltage by setting a resistance value, and as shown in FIG. It can be set arbitrarily, and if it is set to 100%, it will be the same as when starting directly. By turning the knob and setting the resistance value, for example, Vl+V! When one of the command signal voltages of +v3, . . .

The initial voltage duration setting device 10 defines the time period during which the starting initial voltage continues, and the time period for maintaining the starting initial voltage set by the starting initial voltage setting device 9 is set to, for example, 0.
il+h shown in FIG. 5(b) in the range of ~lO seconds.
, t+... can be arbitrarily selected.

Note that a known electronic timer may be employed as this initial voltage duration setting device 10.

The voltage increase rate setter 11 sets the starting voltage increase rate β8. from the initial value. β2. β, . . . [see Fig. 5(C)], which defines the point P determined by the starting initial voltage setting device 9 and the initial voltage duration setting device 10 (see Fig. 5(f,))]
It is designed to realize a voltage rise that rises almost linearly as shown by arrow A from the angle A, and can be selected within the range of 90 to 30 degrees, for example.

Although the load current limit value setting device 12 differs depending on the capacity of the squirrel cage induction motor 1, the load current value at the time of starting, that is, the starting load current value, is specified to be thicker than (close to) the rated current, and the starting current is set to a value thicker than (close to) the rated current. For example, the rated current is 100 to 150
It can be set in a range of %. This is the fifth
11+ 12. shown in figure (d). It can be arbitrarily selected, such as Is.

The function generator 14 generates a combination of command signals shown in FIGS. 5(a) to 5(c) according to the values set by the starting initial voltage setting device 9, the initial voltage duration setting device 10, and the voltage increase rate setting device 11. A starting voltage command pattern is generated which makes the primary voltage applied to the squirrel cage induction motor l a desired starting voltage application pattern, as shown by the solid line in FIG. 5(f) synthesized by the above. In addition, Fig. 5 (g) and (h)
The portion from point P until reaching the rated voltage may be deformed to form a polygonal line or curve as shown in FIG.

The limit signal generator 13 determines whether the load current increasing due to the primary voltage applied during starting of the squirrel cage induction motor l exceeds a load current limit value set by the load current limit value setting device 12, for example, 130%. is exceeded, a limit signal is issued to hold the voltage increase command signal of the starting voltage command pattern generated by the function generator 14 until the load current of the squirrel cage induction motor 1 becomes equal to or less than the load current limit value. It is designed to be output to a function generator 14. That is, when the limit signal is input from the limit signal generator 13 to the function generator 14, the starting voltage command pattern generated by the function generator 14 is as shown by the broken line of arrow B in FIG. 5(f). Stop the voltage increase. Then, the portion indicated by the two-dot chain line where the load current of the squirrel cage induction motor l exceeds, for example, 130% of the rated current in the portion indicated by the arrow M in FIG.
The current is maintained at 130% as indicated by a to prevent excessive load current from flowing to the squirrel cage induction motor 1. Thereby, the current of the generator is reduced to its short-term overload capacity, e.g.
It can be kept within 0%.

When the squirrel cage induction motor I is accelerated after a certain period of time, the load current decreases with the acceleration.

If it is less than 130% as shown by arrow N in Figure 6,
From point Q in FIG. 5(f), the starting voltage command pattern is returned to pattern C parallel to the solid line A of the starting voltage command pattern generated by the function generator 14, as indicated by the broken line.

The gate control circuit 16 includes a phase control circuit 17 shown in FIG.
It is composed of a gate trigger circuit 18, which outputs a trigger signal to the gate of the thyristor 15 based on the starting voltage command pattern in the function generator 14, and applies a primary voltage to the squirrel cage induction motor 1 to form a starting voltage application pattern. Then, the thyristor 15 is controlled.

According to the configuration described above, the squirrel cage induction motor 1 can be started in the following manner. First, the resistance values are changed by turning the respective knobs of the starting initial voltage setting device 9, initial voltage duration setting device 10, voltage increase rate setting device 11, and load current limit value setting device 12 to make temporary settings. For example, a starting voltage command pattern as shown by the solid line in FIG. 5(f) is generated by the function generator 14. Starting switch 2, 3.
6, a voltage is applied to the squirrel cage induction motor 1 in a starting voltage application pattern as shown in FIG. 7(a). At this time, a starting current as shown in FIG. 8(a) flows, and the mechanical device driven by the squirrel cage induction motor 1 is started. If you need to increase the starting torque or shorten the acceleration time, you can slightly increase the starting initial voltage setting device 9, and the starting voltage application pattern will become as shown in Figure 7(b). The current changes as shown in Fig. 8(b).For example, by controlling the starting voltage as shown in Fig. 7(C), the current changes as shown in Fig. 8(C).
), the acceleration current becomes almost constant.

By the way, when the primary voltage applied to the squirrel-cage induction motor 1 increases as shown in FIG. 7(a), the diesel engine and generator that make up the private power generator exceed their respective short-term overload capacities. If there is a concern, set a limit load current value using the load current limit value setting device 12 so as not to exceed the short-term overload tolerance. As a result, when the load current detected by the current transformer of the squirrel cage induction motor 1 during starting exceeds the set value of 130% as shown in FIG. A limit signal generator 13 is sent to a function generator 14 that generates a starting voltage command pattern for a voltage application pattern.
A limit signal for stopping the voltage increase in the starting voltage command pattern is output from the starting voltage command pattern.

The limit signal causes the function generator 14 to
＞ As shown by the broken line in the arrow B part, the increase in the voltage applied to the motor is suppressed, and the load current is reduced to 1 as shown in the solid line in the arrow Ma in FIG.
The load current decreases as the load current accelerates during the 0 time period, which is suppressed to 30%, so when the current reaches the set current or lower, the output of the limit signal is stopped, and at point Q in Fig. 5(f). Then, the voltage applied to the motor resumes increasing. Note that, if the load current exceeds the set value while the applied voltage is increasing, the above operation is performed each time.

If the setting positions of the knobs of the setting devices 9, 10, and 11 are fixed, then when starting the electric motor 1, the specific starting voltage command pattern generated by the function generator 14 will be used. It is started according to the starting voltage application pattern based on the starting voltage application pattern. In this state, the load current is suppressed as described above, but if it takes too long to start, change the set position of the knobs on the setting device 9, 10, and 11 at the initial setting stage as described above. Bye.

As can be seen from the above explanation, it is possible to apply a starting voltage corresponding to the starting torque at the beginning of a certain period of time and gradually increase the starting voltage within a range that does not interfere with starting the load.
The occurrence of a large starting peak current in the squirrel-cage induction motor is suppressed, and if the load current of the squirrel-cage induction motor exceeds the set value during that time, the current is controlled to the set value, making soft starting possible. Become. Therefore, there is no shock to the load at startup, and even if there are other loads on the same power source, a drop in rotational speed due to a voltage drop in the power source due to the peak starting current is avoided. During this time, the short-term overload capacity of the generator is not exceeded.
The generator capacity and receiving transformer capacity can also be small.

The above starting voltage control can be changed by changing the settings of each setting device, so for example, if the inertia is large and starting torque is required and it takes time to start, operate one of the setting devices above, If a function generator generates a starting voltage command pattern according to the starting voltage command pattern, the starting voltage application pattern can be arbitrarily selected while checking the starting condition of the load. If the load driven by the motor changes, adjustments can be made accordingly, making it possible to achieve near-optimal starting. Furthermore, as a static starter device, maintenance and inspection efforts can be significantly reduced, and the device can be small, lightweight, and inexpensive.

By the way, the duration set by the initial voltage duration setting device 10 may be set to zero seconds depending on the type of load, so the initial voltage duration setting device 10 may not be necessary. In such a case, only the starting initial voltage setting device 9 and the voltage increase rate setting device 11 are provided, and a function generator 14 generates a combined starting voltage command pattern based on the set values thereof. This also allows the primary voltage of the above-mentioned and similar desired starting voltage application pattern shown by the solid line in FIG. 9 to be applied to the motor from the thyristor 15. In this case, there is an advantage that the configuration of the starting device is simple.

FIG. 4 shows a power limit value setter 19 and a power value calculator 20 as shown in FIG. 2 in place of the load current limit value setter 12 and limit signal generator 13 (see FIG. This is a standard circuit in which a limit signal generator 21 and a limit signal generator 21 are provided.

For example, small volume resistors 9, 10, 11, and 19 are planned to be attached to the control unit 5.
Each functions as a starting initial voltage setter, an initial voltage duration time setter, a voltage increase rate setter, and a power limit value setter. The power value calculator 20 calculates a power value (KW) from the load current and load voltage of the squirrel cage induction motor 1 during startup, taking into account the automatically calculated power factor. Limit signal generator 21
determines whether the power value input from the power value calculator 20 exceeds the power limit value set by the power limit value setter 19, which is a small volume type resistor, and if it exceeds the power value, the control unit A limit signal is output to 5.

FIG. 2 is a block diagram of the overall configuration of the starting device shown together with a schematic system diagram, and includes a control unit 5 that functions in substantially the same way as the example described above. The power limit value setter 19 varies depending on the capacity of the squirrel cage induction motor l.
For example, it can be set to 100 to 130% of the rated power value, as shown in Figure 5 (e),
It can be arbitrarily selected within that range, such as s. In such an example as well, the voltage increase command signal is temporarily held based on a similar limit signal, and the state shown by the two-dot chain line R in FIG. The squirrel cage induction motor l is started while suppressing the KW so as not to become excessively high. therefore,
The generator engine will be operated within its overload capacity for a short period of time, eliminating the need for a large-capacity engine.

In this example as well, depending on the type of load, the duration set by the initial voltage duration setting device 10 may be set to zero seconds, so the initial voltage duration setting device 10 may not be necessary. This has the advantage of simplifying the configuration of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a starting device for a squirrel-cage induction motor that suppresses load current according to the present invention, FIG. 2 is a block diagram of a starting device for a squirrel-cage induction motor that suppresses electric power, and FIGS. Figure 4 is a standard circuit diagram of the starting device in each example, Figures 5 (a) to (e) are function generation command signal diagrams corresponding to the setting values in each setting device,
Figures 5 (f) to (h) are examples of starting voltage command patterns in the function generator, Figure 6 is a current change diagram when suppressing excessive load current of the motor, and Figures 7 (a) to ( c) is an example of a starting voltage application pattern applied to a squirrel cage induction motor;
Figures 8 (a) to (C) are graphs of changes in starting current of the motor corresponding to starting voltage application patterns, Figure 9 is a starting voltage command pattern when the initial voltage is not continued, and Figure 10 is excessive power in the motor. It is a KW change diagram when suppressing. l-・-・Squirrel cage induction motor, 9-Starting initial voltage setting device (volume-type small resistor), 1 (L-・Initial voltage duration setting device (volume-type small resistor), 11-・-Voltage rise Rate setting device (volume type small resistor), 12 - Load current limit value setting device (volume type small resistor), 13
- Limit signal generator, 14 - Function generator, 15 - Thyristor, 16 - Gate control circuit, 19 - Power limit value setter (volume type small resistor), 20 - Power value calculator, 21 -Limit signal generator. Patent applicant: Toyo Kiden Co., Ltd. Agent: Patent attorney: Katsutoshi Yoshimura (and one other person) Figure (a) Figure (b) Figure (d), paper, J-9 rotating angle ring (0) Figure (f) Figure (h)

Claims (4)

[Claims] (1) A starting device for an induction motor that uses a thyristor to control the primary voltage of a squirrel-cage induction motor includes an initial starting voltage setting device that sets the initial value of the starting voltage, and a starting voltage setting device that sets the starting voltage from the initial value. a voltage increase rate setting device for setting the rate of increase; a load current limit value setting device for setting the load current limit value of the squirrel cage induction motor; and a voltage increase rate setting device for setting the load current limit value of the squirrel cage induction motor; A function generator that generates a starting voltage command pattern for making the primary voltage applied to the squirrel cage induction motor a desired starting voltage application pattern by synthesizing command signals; It is determined whether the load current limit value set by the value setting device is exceeded, and if it is exceeded, the voltage increase command signal of the starting voltage command pattern generated by the above function generator is applied to the load of the squirrel cage induction motor. A limit signal generator that outputs a limit signal to the function generator to hold the current until it becomes equal to or less than the load current limit value, and a trigger signal based on the starting voltage command pattern in the function generator, which is a primary voltage application pattern that becomes the starting voltage application pattern. A starting device for a squirrel cage induction motor, comprising: a gate control circuit for applying voltage to the squirrel cage induction motor using a thyristor; (2) In addition to the starting initial voltage setting device, voltage increase rate setting device, load current limit value setting device, limit signal generator, and gate control circuit according to claim 1, a time period during which the starting initial voltage continues is set. By combining the initial voltage duration setting device and command signals according to the values set by the above-mentioned starting initial voltage setting device, initial voltage duration setting device, and voltage increase rate setting device, the primary voltage applied to the squirrel cage induction motor can be set to the desired value. A starting device for a squirrel cage induction motor, comprising: a function generator that generates a starting voltage command pattern for use as a starting voltage application pattern; (3) A starting device for an induction motor that uses a thyristor to control the primary voltage of a squirrel cage induction motor, which includes an initial starting voltage setting device that sets the initial value of the starting voltage, and a starting voltage setting device that sets the starting voltage from the above initial value. a voltage increase rate setting device for setting the rate of increase; a power limit value setting device for setting the power limit value of the squirrel cage induction motor; and a command signal according to the values set by the starting initial voltage setting device and the voltage increase rate setting device. A function generator that generates a starting voltage command pattern to make the primary voltage applied to the squirrel-cage induction motor a desired starting voltage application pattern, and a power value calculator that calculates the power value of the squirrel-cage induction motor. , It is determined whether the power value from the power value calculator exceeds the power limit value set by the power limit value setting device, and if it exceeds the power value, the starting voltage command pattern generated by the function generator is determined. a limit signal generator that outputs a limit signal to a function generator to hold the voltage increase command signal until the power value of the squirrel cage induction motor becomes equal to or less than the power limit value; and a starting voltage command pattern in the function generator. 1. A starting device for a squirrel-cage induction motor, comprising: a gate control circuit for applying a primary voltage, which is a starting voltage application pattern, to the squirrel-cage induction motor using a thyristor in accordance with a trigger signal based on the starting voltage application pattern. (4) In addition to the starting initial voltage setter, voltage increase rate setting device, power limit value setting device, power value calculator, limit signal generator, and gate control circuit according to claim 3, the starting initial voltage continues. The primary voltage applied to the squirrel-cage induction motor is created by combining the initial voltage duration setting device that sets the time, and the command signal according to the setting values from the above-mentioned starting initial voltage setting device, initial voltage duration setting device, and voltage increase rate setting device. A starting device for a squirrel cage induction motor, comprising: a function generator that generates a starting voltage command pattern for adjusting the voltage to a desired starting voltage application pattern.