Installation of PLC

PLC is suitable for most industrial sites, but it still has certain requirements for usage, environmental temperature, etc. Controlling the working environment of PLC can effectively improve its efficiency and lifespan. When installing a PLC, avoid the following places:

(1) The range of ambient temperature exceeding 0~50 ℃

(2) Relative humidity exceeding 85% or presence of dew condensation (caused by temperature fluctuations or other factors);

(3) Direct sunlight;

(4) Corrosive and flammable gases, such as hydrogen chloride, hydrogen sulfide, etc;

(5) Check for iron filings and dust;

(6) Frequent or continuous vibration, with a vibration frequency of 10-55Hz and an amplitude of 0.5mm (peak to peak);

(7) Impact exceeding 10g (Gravitational acceleration).

There are mounting holes on the four corners of the small programmable controller housing. There are two installation methods, one is to fix with screws, and different units have different installation dimensions; The other is DIN (German Republic Standard) rail fixation. Installation clamp plates for DIN rails, one pair on the left and one pair on the right.

On the track, first install the left and right clamping plates, install the PLC, and then tighten the screws. In order to ensure the reliability of the control system, programmable controllers are usually installed in a control cabinet with a protective casing to prevent dust, oil stains, and water splashing. In order to ensure that the temperature of the programmable controller remains within the specified ambient temperature range during operation, the installation machine should have sufficient ventilation space, and there should be a spacing of more than 30mm between the basic unit and the expansion unit. If the surrounding environment exceeds 55C, install an electric fan and force ventilation.

In order to avoid electrical interference from other peripheral devices, programmable controllers should be kept as far away from high-voltage power lines and equipment as possible, and a distance of at least 200mm should be left between programmable controllers and high-voltage equipment and power lines.

When the programmable controller is installed vertically, it is necessary to strictly prevent wire heads, iron filings, etc. from falling into the interior of the programmable controller from the ventilation window, causing a short circuit on the printed circuit board, making it unable to work properly or even permanently damaged.

2. Power wiring

The PLC power supply is 50Hz, 220V ± 10% AC. The FX series programmable controller has a DC 24V output terminal. This terminal can provide DC 24V power supply for input sensing (such as photoelectric switches or proximity switches).

If the power supply fails and the interruption time is less than 10ms, the PLC operation will not be affected. If the power interruption exceeds 10ms or the power decrease exceeds the allowable value, the PLC will stop working and all output points will be disconnected simultaneously. When the power is restored, if the RUN input is turned on, the operation will proceed automatically.

The PLC itself has sufficient resistance to interference from the power cord. If the power interference is particularly severe, an isolation transformer with a ratio of 1:1 can be installed to reduce interference between the equipment and the ground.

3. Grounding

A good grounding is an important condition to ensure that the PLC can work properly and avoid accidental voltage surge hazards. The grounding wire is connected to the grounding terminal of the machine, and the basic unit is grounded. If an expansion unit is to be used, its grounding point should be connected to the grounding point of the basic unit. In order to suppress interference on the power supply, input, and output terminals, a dedicated ground wire should be connected to the programmable controller, and the grounding point should be separated from the grounding point of the power equipment (such as the motor). If this requirement cannot be met, it is also necessary to achieve common grounding with other equipment and prohibit series grounding with other equipment. The grounding point should be as close as possible to the PLC.

4. DC 24V terminal

When using input devices with passive contacts, the internal 24V power supply of the PLC provides a current of 7mA per point to the input terminal through the input device.

The 24V terminal on the PLC can also provide 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 extended crew member is used, the 24V terminals of the basic unit and the extended unit should be connected. Additionally, no external power supply can be connected to this terminal.

If overload occurs, the voltage will automatically drop, and this input point will not have any effect on the programmable controller.

The number of input points for each model of PLC is specified. For each unused input point, it does not consume power, so in this case, the ability of the 24V power supply terminal to provide external current can be increased.

The empty terminal of the FX series PLC cannot be used under any circumstances.

Spot Products