In daily use, power equipment is sometimes prone to failure, so analyzing the phenomenon and finding the cause of the failure in time is the key to find out the power failure. The basic theory of electrician is the basis of analysis, which combines the full understanding of the structure, principle and performance of power device with the practice of fault. Troubleshooting is an important work of maintenance personnel. To completely eliminate faults, we must know the causes of faults. More importantly, we must be able to analyze and solve faults theoretically, have certain professional theoretical knowledge and master troubleshooting methods.

There may be many causes of power failure. It is important to find out the main causes among the many causes and use methods to eliminate the failure. For the same fault form, the causes of the fault may be various. Among these reasons, which one makes the equipment unable to operate needs more in-depth and careful analysis. For example: if the power equipment is used for the first time, it should be checked and analyzed from the aspects of power supply, circuit, motor and load; If the power equipment is used for the last time after repair, the inspection and analysis of the motor itself should be started; If the equipment suddenly fails to operate after running for a period of time, it should be checked and analyzed from the aspects of power supply and control elements. Through the above process, the specific cause of power equipment failure is determined. The troubleshooting of power equipment includes the following methods:

1. Resistance test method

Resistance test method is a common detection method. It usually refers to a method of measuring whether the motor, line and contact meet the nominal value and whether they are on and off by using the resistance gear of multimeter, or measuring the insulation resistance between phase and phase, phase and ground by megger. When measuring, pay attention to the selection of the range used and the accuracy of the calibration table. Generally, when using the resistance method for measurement, the general practice is to select the low-grade first. At the same time, pay attention to whether the measured line has a circuit, and live measurement is strictly prohibited.

2. Voltage test method

Voltage test method refers to a method of measuring the voltage value in the circuit by using the corresponding voltage gear of the multimeter. Usually, when measuring, sometimes measure the voltage of power supply and load, and sometimes measure the open circuit voltage to judge whether the line is normal. When measuring, pay attention to the gear of the meter and select the appropriate range. Generally, when measuring unknown AC or open circuit voltage, the high-grade voltage is usually selected to ensure that it will not operate under high voltage and low range, so as to avoid damaging the meter; When measuring DC at the same time, pay attention to the positive and negative polarity.

3. Current test method

Current test method is usually used to measure whether the current in the line conforms to the normal value in order to judge the cause of the fault. For the weak current circuit, the current gear of ammeter or multimeter is often connected in series in the circuit for measurement; Clamp on ammeter is often used to detect strong current circuit.

4. Instrument test method

With the help of various instruments and meters to measure various parameters, such as observing the changes of waveform and parameters with oscilloscope, so as to analyze the causes of faults. It is mostly used in weak current lines.

5. Routine examination method

Rely on people's sensory organs (such as burning smell, ignition and discharge of some power equipment in use) and with the help of ~ some simple instruments (such as multimeter) to find the cause of the fault. This method is commonly used in maintenance and is also the first to be used.

6. Replacement of original parts

That is, when a device or circuit board is suspected to be faulty, but cannot be determined, and there are substitutes, the test can be replaced to see whether the fault disappears and whether it can return to normal.

7. Direct inspection method

The suspected fault point can be directly checked when understanding the cause of the fault or judging the location of the fault according to experience.

8. Stepwise exclusion method

In case of short circuit fault, the fault range and fault point can be determined by gradually cutting off part of the line.

9. Adjusting parameter method

In some cases, in case of failure, the components in the line are not necessarily broken, and the line contact is also good. Only because some physical quantities are adjusted improperly or the operation time is long, the system parameters may be changed or the system value cannot be corrected automatically due to external factors, resulting in the system can not work normally. At this time, it should be adjusted according to the specific conditions of the equipment.

10. Principle analysis method

According to the composition schematic diagram of the control system, by tracking the signal associated with the fault, analyze and judge, find out the fault point and find out the cause of the fault. Using this method requires maintenance personnel to have a clear understanding of the working principle of the whole system and unit circuit.

11. Comparison, analysis and judgment

It is based on the working principle of the system, the action procedure of the control link and the logical relationship between them, combined with the fault phenomenon, to compare, analyze and judge, reduce the measurement and inspection links, and quickly judge the fault range.

The above methods are commonly used in power equipment troubleshooting, which can be used alone or mixed. In case of actual power failure, they should be used flexibly in combination with relevant specific conditions in order to effectively solve the failure.