Specific methods for troubleshooting electrical faults

Electricians must have professional knowledge and sufficient theoretical principles as a basis to ensure that they can immediately and accurately judge and analyze faults. Here are several commonly used methods for troubleshooting power system faults.

1. Resistance test method Resistance test method is a commonly used measurement method. It usually refers to a method of using the resistance range of a multimeter to measure whether the motor, line, contact, etc. meet the nominal value and whether they are on and off, or using a megohmmeter to measure the insulation resistance between phases and phases, and between phases and ground.

When measuring, pay attention to the accuracy of the range and calibration table used. Generally, when using the resistance method to measure, the general practice is to use a low range first. At the same time, pay attention to whether the measured line has a loop, and it is strictly forbidden to measure with power on.

2. Voltage test method Voltage test method refers to a method of using the corresponding voltage range of a multimeter to measure the voltage value in the circuit. Usually, when measuring, sometimes the voltage of the power supply and load is measured, and sometimes the open circuit voltage is measured to determine whether the line is normal.

When measuring, you should pay attention to the gear of the meter and choose the appropriate range. Generally, when measuring unknown AC or open-circuit voltage, the highest gear of voltage is usually selected to ensure that it is not operated at high voltage and low range to avoid damaging the meter; at the same time, when measuring DC, pay attention to the positive and negative polarity.

3. Current test method The current test method is a method that usually measures whether the current in the circuit meets the normal value to determine the cause of the fault. For weak current circuits, the current range of the ammeter or multimeter is often connected in series in the circuit for measurement; for strong current circuits, clamp ammeters are often used for detection.

4. Instrument test method uses various instruments to measure various parameters, such as using an oscilloscope to observe the changes in waveforms and parameters, so as to analyze the cause of the fault, and is mostly used in weak current lines.

5. Conventional inspection method relies on human sensory organs (such as: some electrical equipment has a burnt smell, sparking, discharge, etc.) and uses some simple instruments (such as: multimeter) to find the cause of the fault. This method is most commonly used in maintenance and is also the first to be used.

6. Replacement of original parts method: when you suspect that a device or circuit board is faulty but cannot be confirmed and there are substitute parts, you can replace it for testing to see if the fault disappears and returns to normal.

7. Direct inspection method: when you understand the cause of the fault or judge the location of the fault based on experience, you can directly check the suspected fault point.

8. Step-by-step elimination method: if a short circuit fault occurs, you can gradually cut off part of the line to determine the fault range and fault point.

9. Adjustment parameter method: in some cases, when a fault occurs, the components in the line are not necessarily bad, and the line contact is also good. It is just that some physical quantities are not adjusted properly or the running time is long. It is possible that the system parameters change due to external factors or the system values ​​cannot be automatically corrected, causing the system to fail to work properly. At this time, adjustments should be made according to the specific situation of the equipment.

10. Principle analysis method: according to the composition schematic diagram of the control system, by tracking the signals associated with the fault, analyze and judge, find the fault point, and find out the cause of the fault. The use of this method requires maintenance personnel to have a clear understanding of the working principle of the entire system and unit circuit.

11. Comparison, analysis and judgment method It is based on the working principle of the system, the action procedures of the control links and the logical relationship between them, combined with the fault phenomenon, to compare, analyze and judge, reduce the measurement and inspection links, and quickly determine the scope of the fault.

The above commonly used methods can be used alone or in combination. When encountering actual electrical faults, they should be flexibly applied in combination with specific circumstances.