Progressive method of robustness of automatic control cabinets – Reynolds

1. Appropriate working environment

1. The ambient temperature is suitable

All manufacturers have certain rules for active temperature control cabinets. The PLC promises that the ambient temperature is usually about 0 to 55 ° C, so during the equipment process, this heating element is not placed in the PLC; The PLC should be surrounded by sufficient ventilation and heat dissipation space; Do not put PLC equipment into direct sunlight or very close to heating, heaters, power supplies and other equipment, during which heating; Assuming that the temperature is too high, the control cabinet and the cabinet should be drunk and actively controlled, and if the temperature of the cabinet is too high, the ventilation fan should be equipped in the cabinet.

2. The ambient humidity is suitable

In order to ensure the insulation function of the active control cabinet, the relative humidity of the air in the PLC working environment is generally less than 85%. Excessive humidity can also affect the accuracy of I/O devices. Therefore, the active control cabinet should not be installed in the center of the dew and rain.

3. Be aware of environmental pollution

In the center of the equipment with a large number of pollutants such as dust, smoke, iron powder, etc., the control cabinet is automated. , candle gases and flammable gases are not suitable, especially in the presence of corrosive gases, which tend to provoke corrosion of components and printed circuit boards. Assuming that the equipment can only be in such a center, the active control cabinet can be turned off when the temperature is agreed, the PLC equipment can be placed in a more closed control room, or the air purification equipment can be installed.

4. From the source of oscillations and shocks

The control cabinet equipped with PLC should be far away from the center of large oscillation impact, especially the center of continuous and frequent oscillation, if necessary, appropriate measures can be taken to reduce the impact of oscillation and impact, and prevent loose wires or plug-ins.

5. The root cause of strong disturbance.

PLC is far away from strong disturbance sources, such as high-power thyristor equipment, high-frequency equipment and high-power equipment; The PLC should be located from strong magnetic fields, strong radioactive sources and simple onset of strong static electricity.

Progressive method of robustness of automatic control cabinets – Reynolds

Progressive method of robustness of automatic control cabinets – Reynolds

2. Reasonable equipment wiring

Keep an eye on the power of the device

The primary way of PLC power supply disturbance. There are two power supply systems: internal and external.

An external power supply is used to drive the PLC output device (load) and provide input signals, also known as a user power supply. There can be multiple standards for an external power supply for the same PLC. The capacity and function of the external power supply are determined by the output equipment and input circuit of the PLC, because the I≤O circuit of the PLC has filtering and blocking functions, and the external power supply has little impact on its function, so the request for the external power supply is not high.

Under the condition of strong anti-disturbance ability or high reliability, the shielding barrier transformer is used to supply power to the PLC system. The LC filter circuit can also be connected in series to the secondary side of the barrier transformer. Together, the following issues should be paid attention to during the equipment process:

The top results are as follows:

1) The connection between the transformer and twisted pair SUI PLC and I/O power supply is blocked and manipulated in serial mode.

2) The power cord of the system should be thick enough to reduce the line voltage drop caused by the operation of large-capacity equipment;

3) When an external DC power supply is used in the PLC input circuit, SUI can use the dispatched power supply to ensure the correctness of the input signal. Otherwise, the PLC can receive the error signal.

Three. Proper grounding

The outstanding grounding automation control cabinet is an important condition for safe and reliable operation. In order to suppress disturbances, the commonly used automatic control cabinet itself grounding equipment and other equipment, which can be used for a common denominator, but prevent the use of the tandem method in the air, because this will incur the potential difference between the grounding PLC and the equipment.

Progressive method of robustness of automatic control cabinets – Reynolds

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