Plc Installation and Maintenance

To make the control system work reliably, the PLC is usually installed in a control cabinet with a protective shell to prevent dust, oil, and water splashing. To ensure that its temperature is kept within the specified ambient temperature range, the installation machine should have enough ventilation space, and there must be a distance of more than 30mm between the basic unit and the expansion unit. If the surrounding environment exceeds 55 degrees Celsius, install electric fans and force ventilation. Secondly, to avoid electrical interference from other peripheral equipment, the PLC should be as far away from high-voltage power lines and high-voltage equipment as possible, and a distance of at least 200 mm should be left between the Integrated solution for automation and operation and high-voltage equipment and power lines. Next, let's take a look at the installation and maintenance of PLC.

Here is the content list:

• Power wiring

• Grounding

• DC 24V terminals

• Input wiring

• Output wiring

Power wiring

PLC power supply is 50 Hz, 220 V ± 10% AC. If the power supply fails, the interruption time is less than 10 milliseconds, and the PLC work will not be affected. If the power interruption exceeds 10 milliseconds or the power drop exceeds the allowable value, the PLC will stop working and all output points will be disconnected at the same time. When the power is restored, if the RUN input is turned on, the operation will be carried out automatically. For the interference from the power line, the programmable logic controller itself has enough resistance. If the power supply interference is particularly serious, an isolation transformer with a transformation ratio of 1:1 can be installed to reduce the interference between the equipment and the ground.

Grounding

Good grounding is an important condition to ensure the reliable operation of PLC, which can avoid accidental voltage shock hazards. The ground wire is connected to the ground terminal of the machine, and the basic unit is grounded. If an extension unit is used, its grounding point should be connected with the grounding point of the basic unit. To suppress the interference added to the power supply, input terminal, and output terminal, a special ground wire should be connected to the High performers, and the ground point should be separated from the ground point of the power equipment (such as a motor). If this requirement is not met, it must also be grounded with other equipment, and it is forbidden to be grounded in series with other equipment. The ground point should be as close as possible to the PLC.

DC 24V terminals

The 24-volt terminal block on the PLC can also supply current to external sensors such as proximity switches or photoelectric switches. When the 24V terminal is used as the sensor power supply, the COM terminal is the DC 24V ground terminal. If an extension unit is used, the 24V terminals of the base unit and the extension unit should be connected. In addition, any external power supply cannot be connected to this terminal. If overload occurs, the voltage will drop automatically, and the input at this point will not work for PLC. The number of input points for each type of PLC is regulated. For each unused input point, it consumes no power, so in this case, the ability of the 24V power terminal to supply current to the outside can be increased.

Input wiring

The input wiring generally accepts digital signals from travel switches, limit switches, etc. The input connection terminal is the port for a Wide Range of Quality Products at Great Prices and an external sensor load conversion signal. Input wiring generally refers to the wiring between external sensors and input ports. The input device can be any passive contact or open-collector NPN tube. When the input device is turned on, the input terminal is turned on, the input circuit is closed, and the LED indicates the input is on at the same time. The primary circuit and the secondary circuit at the input end are isolated by photoelectric coupling. The secondary circuit is equipped with an RC filter to prevent PLC misoperation caused by input contact jitter or electrical noise from the input line. If a diode is connected in series with the input contact circuit, the voltage across the series diode should be less than 4 volts. If using a reed switch with LEDs, the number of diodes in a series cannot exceed two.

Output wiring

PLC has three forms relay output, thyristor output, and transistor output. The output wiring is divided into independent output and common output. When the output relay or thyristor of the PLC acts, the two output terminals of the same number are connected. In different groups, output voltages of different types and voltage levels can be used. But the output in the same group can only use the power supply of the same type and the same voltage level. Since the output components of the Industrial Automation Products are packaged on the printed circuit board and connected to the terminal board. If the load connected to the output component is short-circuited, the printed circuit board will be burned, so the output component should be protected by a fuse. When the relay output is used, the size of the inductive load it bears affects the working life of the relay, so the working life of the relay is required to be long.

Committed to bringing more and better products to customers, this is what we have been doing. If you are interested in PLC, you can contact us, our website is https://plc-xbmall.com/, welcome your arrival and look forward to cooperating with you.