JPS61173695A - Monitor of motor load - Google Patents

Abstract

PURPOSE:To enhance the reliability of a monitor by comparing a signal in response to the variation with a set level even when the load of a motor varies. CONSTITUTION:A microcomputer 7 presets an alarm level by a programmer 8, always compares signals from an A/D converter 6, and operates an external contact 9 if the signal becomes above or below the upper limit value or higher or lower limit value or lower. When the level is completely set and the computer 7 moves to executing stage, a timer is first started to read out data from an initial input power source monitor 4. The read data value is first compared with an overload alarm level of each of preset levels, it generates an alarm when larger than it, and compares with next overload preparatory level when smaller than it, and generates an alarm when larger that it.

Description

[Detailed Description of the Invention] [Object of the Invention] To 11L 1 The present invention relates to a load on an electric motor that drives a power device such as a pump, a conveyor, or a machine tool used in a ship, a sewage treatment plant, a production factory, etc. The invention relates to a device for monitoring.

11 Generally speaking, when the load on a motor exceeds a preset upper or lower limit, in order to prevent disasters or breakdowns,
Issue an alarm or stop pumps, etc.

Most conventional motor load monitoring and alarm devices, such as ammeters and meter relays, directly monitor the current flowing through the motor and determine whether the current value is above or below a preset level. When this occurs, a relay contact is activated to issue an alarm. Moreover, 1 signal per human signal
It was common practice to install multiple monitoring devices and make individual adjustments.

However, the conventional monitoring device described above not only requires monitoring equipment corresponding to the number of motors, but also has the disadvantage that level settings must be made individually.

In addition, since conventional monitoring devices use the current flowing through the motor as a monitoring signal, not only does the relay operate at a fixed set level (current value) even when the motor voltage changes, but the level changes as the motor load changes. Even if the settings are changed, the relationship between the load and the corresponding level is complicated, and it is difficult to calculate an appropriate setting level, resulting in a disadvantage that the accuracy of the monitoring device deteriorates.

Furthermore, the alarm level is usually set at two points, an upper limit value and a lower limit value, but if you intend to set, for example, a preliminary alarm level in addition to the above, it is necessary to add a circuit for that purpose. Met.

The present invention has been made to eliminate the drawbacks of the conventional devices described above, and its purpose is to provide a highly reliable monitoring device by comparing a signal corresponding to load fluctuations of an electric motor with a set level. An object of the present invention is to provide a motor load monitoring device capable of simultaneously setting a plurality of levels according to need by processing individual signals with a computer system using a microprocessor.

[Structure of the invention] Hands for doing v.

The motor load monitoring device of the present invention includes an input power monitoring device that detects the load of a motor that drives a power device such as a pump as an input signal and converts it into a current value or voltage value, and a signal from the input power monitoring device. It is characterized by comprising a microcomputer that generates an output signal by comparing the output signal with a preset level, and a contact that is activated by the output signal of the microcomputer, and a plurality of the above-mentioned power units are provided. In this case, each of the plurality of electric motors that drive each power unit is provided with an input power monitoring device, and the signals from the plurality of input power monitoring devices are sequentially switched and unified by a multiplexer, and the microcomputer It is characterized in that it is processed by.

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings.

In this embodiment, a case will be described in which a plurality of pump groups rotationally driven by an electric motor are monitored.

In FIG. 1, 1 is a pump, and a plurality of pumps are installed. 2 is an electric motor that rotationally drives each pump 1,
It is input by the power supply 3.

An input power monitoring device 4 is connected to the power source 3, and converts the load of the electric motor 8!12 into a current value of 4 to 20 mA or a voltage value of 1 to 5 cm, for example.

The signal converted by the input power monitoring device 4 is given to the microcomputer 7 via the multiplexer 5 and A/D converter 6. The multiplexer 5 is configured to sequentially switch over the input power monitoring devices 4 of the individual electric @ 2 and unify them by a timing pulse from the microcomputer 7.

The microcomputer 7 sets the alarm level to the programmer 8.
The external contact 9 is activated when the signal from the A/D converter 6 is constantly compared and the signal is above the upper limit or below the lower limit of the set level.

Next, the operation of the above device will be explained based on the chart 70 shown in FIG.

First, after inputting the input line number, the number of set level points is inputted. In this embodiment, four levels are set.

Next, input settings for the overload warning level, overload preliminary warning level, underload warning level, and underload preliminary warning level.

When the level setting is completed and the computer 7 moves to the execution stage, the timer starts and the first input power monitoring device 4
Data from is read.

This read data value is first compared with the overload alarm level among the above preset levels, and if it is larger than this, an alarm is issued, and if it is smaller, it is compared with the next overload preliminary alarm level, and if it is larger, It issues an alarm, and if it is smaller, it compares it with the next underload alarm level, and if it is smaller, it issues an alarm, and if it is larger, it compares it with the next underload alarm level, and if it is smaller, it issues an alarm, If it is large, NORMΔL is displayed as normal operation.

When the first operation is completed, the multiplexer 5 operates to connect to the next input power monitoring device 4, read the next data, and repeat the operation.

According to this embodiment, since the multiplexer 5 unifies the signals of multiple motors into one signal, the level setting of the upper limit value and the lower limit value can also be done with electric power! [There is no need to set it for each one, and it is possible to unify it into one.]

[Effect of the invention 1] Since the present invention is configured as described above, even when the load on the motor changes, it is possible to obtain a highly reliable monitoring device that compares the signal corresponding to the change with the set level. At the same time, since individual signals are processed by a computer system using a microprocessor, multiple levels can be set at the same time as needed, making it possible to create a detailed alarm system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a control flow chart. 1... Pump, 2... Electric motor, 3... Power supply, 4...
...Input power supply monitoring device, 5...Multiplexer, 6.
... A/D converter, 7... Microcomputer, 8
...Programmer, 9...Contact.

Claims (2)

[Claims] (1) An input power monitoring device that detects the load of a motor that drives a power device such as a pump as an input signal and converts it into a current value or voltage value, and compares the signal from the input power monitoring device with a preset level. 1. A motor load monitoring device comprising: a microcomputer that generates an output signal; and a contact that is activated by the output signal of the microcomputer. (2) A plurality of input power monitoring devices that detect the load of each electric motor that drives a plurality of power devices such as pumps as an input signal and convert it into a current value or voltage value, and a signal from each input power monitoring device. It consists of a multiplexer that is sequentially switched and unified, a microcomputer that generates an output signal by comparing the signal from the multiplexer with a preset level, and a plurality of contacts that are each activated by the output signal of the microcomputer. A motor load monitoring device characterized by: