Precautions for maintenance of electrical control systems for construction machinery

The electrical systems of construction machinery are becoming more and more complex. If you are not careful during maintenance, a small problem will turn into a big failure, causing greater economic losses. The precautions are as follows:

1. First cut off the power supply

During maintenance, in order to disconnect the wires and connectors, the power supply of the entire machine should be cut off first, otherwise the wiring harness, fuse and fuse will be damaged, and sometimes a short circuit in the wires may cause a natural disaster.

2. Correctly identify various wire colors

Imported construction machinery uses codes to indicate the colors of various wires on the wiring harness (see the attached table) to distinguish different wires. The letter on the left represents the base color and the letter on the right represents the marking color.

3. Connect and disconnect terminal connectors correctly

(1) When disconnecting a wire harness, grasp its connector, not the wire itself; first release the latch and then pull the connector.

(2) When inspecting waterproof connectors, be careful not to allow water to enter the connectors. If water enters the connectors, they can only be reconnected after being dried.

(3) Before connecting the terminal connector, the terminal must not be bent or extended outside; if the terminal is rusted, it should be sanded off before installation.

(4) When connecting a terminal connector with a lock, make sure you hear the lock snap into place.

4. Use a circuit tester

(1) When using various circuit testing instruments, you should first understand their working principles and usage conditions. Improper use is strictly prohibited.

(2) When measuring voltage and current, you should select an appropriate measurement range to prevent damage to the instrument, and strictly measure voltage within the current and resistance ranges.

(3) Before measuring, check the number and position of the terminals to be measured against the circuit diagram. If the connector is too small and the instrument probe is too large to make the measurement, you can wrap or tie a thin wire or a pin around the probe to facilitate the measurement.

5. Understand the circuit working principle diagram

The electrical schematic diagram is a diagram of the relationships between the components and devices of the electrical system when they are working normally. Only by reading it can you understand the impact of failures of the components and devices, so that the maintenance work can be carried out smoothly, avoid blind dismantling and save time.

6. Correctly identify the "ground" in the electrical schematic diagram

The negative pole of the battery is a kind of "ground". Since engineering machinery uses negative grounding, the negative pole of the battery is connected to the body, and the body becomes another "ground". When the grounding wire has good performance, these two "grounds" can be considered as one. The voltage and current measured for this "ground" refer to the voltage and current of the measuring point to the negative pole of the battery. In addition, due to the application of microprocessors and a large number of electronic components and devices, a part of the pins are connected to form another "ground". This "ground" is generally relative to the power supply of the microprocessor. The measured voltage and current refer to the voltage and current of the measuring point to the power supply of the microprocessor. Therefore, when performing maintenance measurements, it is necessary to distinguish the relative "ground" of the measured parameters.

7. Keep good records to facilitate technical analysis

When inspecting an electrical system, there may be many parameters to be measured. If you do not record them, some parameters may not be remembered clearly when you analyze them after the measurement. Moreover, some parameters have very small differences in quantity. Keeping records can also provide historical technical data for future troubleshooting.

8. Proper handling of wire harnesses

When bundling wire bundles, try to avoid hard bends and bends; the wire bundles should be kept away from moving parts to prevent them from being pulled apart or worn out; the wire bundles should be kept away from oil and water as much as possible.

9. Pay attention to bandaging or replacing the wires

If the wire is found to be worn, it should be bandaged or replaced immediately. It is best to use waterproof tape for bandaging.

10. Use fuses correctly

When replacing a fuse, be sure to use a product of the same specifications; the copper wire used as an emergency substitute should also be as thin as possible to ensure that the scope of the fault is not expanded when a circuit fault occurs.