JPH0226291A - Motor plant monitor - Google Patents

Abstract

PURPOSE:To monitor the operating state of each motor stably by deciding whether a non-operating motor can be started, on the basis of motor characteristics of a motor in operation and load characteristics of the load of said operating motor. CONSTITUTION:When a motor 41 not in operation is started while a motor 42 is in the operating state, it is first decided on the basis of rotational speed data, torque data and process data of said operating motor 42 whether the power capacity sufficient for the rated operation of said motor is secured or not. When the power capacity is insufficient, starting of the motor 41 is locked. On the other hand, when the power capacity is secured, load characteristics of the operating motor 42 and those of a load 32 are checked. When the voltage drop accompanying starting of said non-operating motor 41 has an adverse influence such as the cessation of operation of the operating motor 42, starting of the motor 41 not in operation is locked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a monitoring device for a motor plant used, for example, in a rolling line.

(Prior Art) As shown in FIG. 3, electric motors 41 and 42 each having a load of 31°3□ such as a pump or a compressor are connected to the power supply bus 2 of a generator 1 via circuit breakers 51°52. In a motor plant, when each motor 41, 42 is composed of a group of induction motors (1M), the starting current of the motor is generally 5 to 7 times the rated current, and the power factor is 15% to 30%. becomes low. Therefore, if the power supply capacity is small when a non-operating motor is started, a large voltage drop occurs throughout the plant, which adversely affects other operating motors.

Therefore, in the past, a monitoring device was used that could monitor the power supply capacity of a plant by importing process data such as current and power into a computer at regular intervals and processing the data. It was confirmed whether sufficient power supply capacity was secured for rated operation.

However, as shown by the solid line M in Fig. 4, the rotational speed (N) of the operating motor increases as the torque increases.
- In contrast to the torque (T) characteristic, if the N-T characteristic of the load connected to the motor is as shown by the broken line in the figure, the torque (T) characteristic is proportional to the square of the voltage, so the non-operating motor When there is a voltage drop accompanying the start-up of the motor, the torque of the operating motor decreases significantly, and when it becomes below the intersection point P of both characteristics M and L, the operating motor becomes insufficient in torque for the relevant load and stops operating.

In other words, although sufficient power supply capacity is secured for the rated operation of the motor, depending on the relationship between the N-T characteristics of the operating motor and the N-T characteristics of the load, the voltage drop due to the startup of the non-operating motor may cause the operating motor to There was a risk that this would lead to negative effects such as suspension of operations.

(Problems to be Solved by the Invention) As mentioned above, conventional motor plant monitoring devices simply monitor the power supply capacity of the plant and provide information for determining whether or not the power capacity is sufficient for the rated operation of the motor. Therefore, depending on the relationship between the N-T characteristics of the operating motor and the N-T characteristics of the load, the voltage drop caused by starting the non-operating motor may cause an adverse effect such as stopping the operation of the operating motor. It was difficult to stably monitor the operating status.

Therefore, the present invention focuses on the N-T characteristics of the operating motor and the N-T characteristics of the load.
An object of the present invention is to provide an electric motor plant monitoring device that can stably monitor the operating status of each electric motor, taking into consideration the relationship with T characteristics, improving monitoring efficiency, and facilitating plant management. It is.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a process for measuring process data such as current and power of the plant in a motor plant in which a plurality of motors each having a load is connected to a power supply bus. data measuring means; power capacity determining means for determining whether there is enough power capacity for rated motor operation based on the process data measured by the process data measuring means; and characteristic data for measuring the rotational speed and torque of the operating motor. a measuring means; a data processing means for processing the speed data and torque data measured by the characteristic data measuring means to obtain motor characteristics; startup determination means for determining whether or not to start the non-operating motor based on the motor characteristics and the load characteristics of the load of the operating motor;
This motor plant monitoring device includes a start prohibition control means for prohibiting the starting of the non-operating motor when the start determining means determines that starting is not possible or when the power source capacity determining means determines that there is no power source capacity.

(Function) With a motor plant monitoring device that takes such measures, it is determined whether or not there is enough power supply capacity for the rated operation of the motor based on process data such as current and power of the plant.
If it is determined that there is no power supply capacity, starting of the idle motor is prohibited. On the other hand, if it is determined that the power supply capacity is available, the rotational speed data and torque data of the operating motor are processed to obtain motor characteristics, and based on the motor characteristics and the load characteristics of the load of the operating motor, the non-operating motor is It is determined whether or not the motor can be started, and if it is determined that the motor cannot be started, the starting of the non-operating electric motor is prohibited.

(Embodiment) Hereinafter, an embodiment in which the motor plant monitoring device of the present invention is applied to the motor plant shown in FIG. 3 will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the apparatus of this embodiment.

In the figure, a process data measuring section 11 measures process data a such as current and electric power of a motor plant, a rotational speed measuring section 12 measures the rotational speed of an operating electric motor, and a torque measuring section Reference numeral 13 is for calculating the total torque C of the operating electric motor IIj. The storage unit 14 includes a buffer for temporarily storing data a to C measured by each of the measurement units 11 to 13, and each load 3. ．． It is equipped with a table etc. in which rotational speed (N)-torque (T) characteristics at 32 are stored in advance. The data processing unit 15 is, for example, a CPU.
(Central processing unit), each measuring section 11 to 1
Process the measurement data from 3 according to a predetermined operation,
This is to diagnose whether or not a non-operating electric motor can be started. The display section 16 and the printing section 17 display or print out the data processing results in the data processing section 15. Control output section 1
8 outputs a control signal d for locking the starting switch of the non-operating motor when the data processing result of the data processing section 15 prohibits starting of the non-operating motor.

Next, the operation of the apparatus of this embodiment will be described in the case where the electric motor 42 is in operation in the electric motor plant shown in FIG. 3, and the idle electric motor 4□ is started.

Note that the N-T characteristic of the operating motor 42 is denoted by M in FIG.
The NT characteristic of the load 32 connected to this electric motor 42 is shown in FIG.

When monitoring is started when starting the non-operating electric motor 41, the process data measurement unit 11 collects process data in total.
111J L, operating electric motor 42 at rotation speed measurement unit 12
The rotational speed of the operating motor 42 is measured, and the torque of the operating electric motor 42 is measured by the torque measurement unit 13. Then, the data processing section 15 executes the data processing shown in FIG. That is, each total as Pl? #1 The process data 81 rotational speed data b and torque data C measured in sections 11 to 13 are each taken in, and the validity of each data a to C is checked. If it is determined that the validity of each data a to c is good, it is checked in P2 whether or not the power supply capacity sufficient for the rated operation of the motor is secured based on the process data a. Here, if the power supply capacity is insufficient, starting of the non-operating motor 41 is prohibited, so a command to lock the start switch of this motor 41 is sent to the control output section 18. Further, a message for prohibiting starting of the non-operating electric motor 41 is displayed on the display unit 16 and printed on recording paper by the printing unit 17, and the process ends.

On the other hand, if the power supply capacity sufficient for the rated operation of the motor is secured, the N-T characteristic of the operating motor 4□ is recognized from the rotational speed data b and torque data C as P3,
As P4, the N-T characteristic quantity of the operating motor 42 and the storage unit 14
The NT characteristic quantity of the load 32 stored in advance is checked. In other words, the torque of the working motor 42 decreases due to the voltage drop accompanying the start-up of the non-operating motor 4 □, but whether this torque drop has an adverse effect such as stopping the operation of the working motor 42 or not, in other words, the torque depends on the motor characteristic M Check whether the value is less than or equal to the intersection point P between and the load characteristics. Then, if there is no possibility that the torque will fall below the intersection point P, it is possible to start the non-operating motors 41, so a message indicating permission to start the non-operating motors 41 is displayed on the display section 16 and printed on a recording paper by the printing section 17. Output and end processing. On the other hand, if there is a possibility that the torque will be below the intersection point P, the non-operating motor 4□ cannot be started, so a message for prohibiting the starting of the non-operating motor 41 is displayed on the display section 16, and a recording paper is printed on the printing section 17. Print out the file and end the process.

With the device of this embodiment that operates as described above, in a motor plant where there are working motors and non-working motors, when starting the non-working motors, it is possible to check whether sufficient power supply capacity is secured for the rated operation of the motors. Of course, it is possible to monitor whether the voltage drop in the plant due to the start-up of a non-operating motor is lower than that of the operating motor based on the N-T characteristics of the operating motor and the N-T characteristics of the load connected to the operating motor. If the power supply capacity is insufficient or if the operation of the operating motors is adversely affected, starting of the non-operating motors can be automatically prohibited.

Therefore, there is no possibility that the activation of the non-operating motors will adversely affect the operation of the operating motors, and the operating state of each motor in the plant can be stably monitored. As a result, monitoring efficiency can be improved and the plant can be easily managed.

Incidentally, in the above embodiment, a case has been shown in which a message for allowing or prohibiting the start of the unoperated motor is output to the display section 16 and the printer 17, but it goes without saying that either one of them may be used.

[Effects of the Invention] As detailed above, according to the present invention, the N
- A motor plant that can stably monitor the operating status of each motor by considering the relationship between T characteristics and N-T characteristics of the load, improves monitoring efficiency, and facilitates plant management. Monitoring equipment can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the data processing section in the same embodiment, FIG. 3 is a diagram showing an example of a motor plant, and FIG. 4 is a diagram showing an example of an electric motor plant. FIG. 3 is a diagram showing an example of the relationship between the NT characteristics of a motor and the NT characteristics of a load. 1... Generator, 2... Power bus, 31.3z...
Load, 4. ．． 42... Electric motor, 11... Process data measurement unit, 12... Rotation speed measurement unit, 13... Torque measurement unit, 14... Storage unit, 15... Data processing unit, 16...・Display section, 17... Print section, 18...
Control output section.

Claims (1)

[Claims] In an electric motor plant in which a plurality of electric motors each having a load are connected to a power supply bus, there is provided a process data measuring means for measuring process data such as current and electric power of the plant, and a process data measuring means based on the process data measured by the process data measuring means. power supply capacity determination means for determining whether there is sufficient power supply capacity for the rated operation of the motor; characteristic data measurement means for measuring the rotational speed and torque of the operating motor;
data processing means for processing the speed data and torque data measured by the characteristic data measuring means to obtain motor characteristics; and a data processing means for obtaining motor characteristics by processing the speed data and torque data measured by the characteristic data measuring means; a start determination means for determining whether or not the non-operating motor can be started based on the characteristics and the load characteristics of the load of the operating motor; 1. A motor plant monitoring device comprising a start prohibition control means for prohibiting starting of an inoperable motor when it is determined that the motor has no capacity.