Routine maintenance of PLC control system - Solutions - Huaqiang Electronic Network

LC03-3.3 SOP8 TVS Static Protection 3.3V

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The daily maintenance and maintenance of plc is relatively simple, mainly to replace the fuse and lithium battery, basically no other vulnerable components. Since the random access memory (RAM), the counter, and the auxiliary relay with the hold function of the user program are all protected by a lithium battery, the life of the lithium battery is about 5 years. When the voltage of the lithium battery is gradually reduced to a certain level, the basic unit of the PLC The battery voltage drops to the indicator light, prompting the user to pay attention to the program supported by the lithium battery can also remain for about a week, the battery must be replaced, which is the main content of daily maintenance.
The steps to replace the lithium battery are:
â–  Before disassembling, let the PLC be powered on for more than 15 seconds (this can charge the capacitor as the backup power of the memory. After the lithium battery is disconnected, the capacitor can supply power to the PLC for a short time to protect the information in the RAM from loss. );
â–  Disconnect the AC power of the PLC;
â– Open the battery cover of the base unit;
â–  Remove the old battery and install a new one;
â–  Cover the battery cover.
Note that the battery replacement time should be as short as possible, generally not more than 3 minutes. If the time is too long, the program in RAM will disappear.
In addition, care should be taken to replace the fuse with the specified model.
Replacement of I/O Modules If a module needs to be replaced, the user should confirm that the modules being installed are of the same type. Some I/O systems allow for a live replacement of the module, while others require a power cut. If the problem is solved after replacement, but fails after a relatively short period of time, the user should check the inductive load that can generate voltage, and may need to suppress its current spike from the outside. If the fuse is easily blown after replacement, it is possible that the module's output current is out of limits or the output device is shorted.
PLC fault diagnosis is a very important issue and is the key to ensure the normal and reliable operation of the PLC control system. This paper discusses the commonly used fault diagnosis methods. In the actual work process, the various unfavorable factors of the PLC should be fully considered, and regular inspections and routine maintenance should be carried out to ensure the safe and reliable operation of the PLC control system.

Regular inspection

PLC is an industrial control device. Although many measures have been taken in terms of reliability, the working environment has a great impact on PLC. Therefore, the PLC should be regularly checked every six months. If the working conditions of the PLC do not meet the standards specified in Table 1, some emergency treatment is required to make the PLC work in the standard environment.

2. Daily maintenance

In addition to the lithium battery and relay output contacts, PLC has basically no other vulnerable components. Due to the random access memory (RAM) of the user program, the counter and the auxiliary relay with the holding function are protected by a lithium battery. The life of the lithium battery is about 5 years. When the voltage of the lithium battery is gradually reduced to a certain extent, the basic unit of the PLC The battery voltage drop indicator lights up. The user is reminded that the program supported by the lithium battery can be kept for about one week, and the battery must be replaced, which is the main content of daily maintenance. Steps to replace the lithium battery:

1 Before disassembly and assembly, the PLC should be energized for more than 15S (this can charge the capacitor as the backup power of the memory. After the lithium battery is disconnected, the capacitor can be temporarily powered by the PLC to protect the information in the RAM from being lost) ;

2 disconnect the AC power of the PLC

3Open the battery cover of the base unit

4 Remove the old battery and install a new battery

5 cover the battery cover

The battery replacement time should be as short as possible, generally not more than 3 minutes. If the time is too long, the program in RAM will disappear.