1. Intuitive method
The intuition method is based on the external manifestations of electrical faults in automated production line equipment, by means of seeing, smelling, listening, etc., to check and judge faults.
1. Check steps
Investigation situation: Inquire about the situation of the operator and the personnel present at the fault, including the external performance of the fault, the general location, and the environmental conditions when the fault occurred. Such as whether there are abnormal gases, open flames, whether the heat source is close to electrical appliances, whether there is corrosive gas intrusion, whether there is water leakage, whether anyone has repaired it, the content of the repair, etc. Preliminary inspection: Based on the investigation, check whether there is damage to the outside of the appliance, whether the wiring is broken or loose, whether the insulation is burnt, whether the blow indicator of the spiral fuse pops out, whether there is water or grease in the appliance, and whether the switch position Whether it is correct etc.
Test run: After preliminary inspection, it is confirmed that the fault will further expand and cause personal and equipment accidents, and then further test run inspection can be carried out. During the test run, attention should be paid to whether there are serious flashovers, abnormal smells, abnormal sounds, etc. Once found, the vehicle should be stopped immediately. Cut off the power. Pay attention to check whether the temperature rise of electrical appliances and the action program of electrical appliances meet the requirements of the schematic diagram of electrical equipment, so as to find the fault location.
2. Inspection method
Observe sparks: The contacts of electrical appliances in automated production line equipment will produce sparks when they close or break a circuit or when wire ends are loose. Therefore, electrical faults can be checked based on the presence and size of sparks. For example, when sparks are found between the normally fastened wire and the screw, it means that the wire end is loose or the contact is poor. When the contacts of the electrical appliance flash over when the circuit is closed or broken, it means that the circuit is connected.
When the main contacts of the contactor controlling the motor have sparks in two phases and no sparks in one phase, it means that the contact of the one phase without sparks is in poor contact or the circuit of this phase is open; the sparks in two of the three phases are larger than normal, and the sparks in one phase are larger than normal. Smaller than normal, it can be preliminarily determined that the motor is short-circuited or grounded between phases; the three-phase sparks are larger than normal, it may be that the motor is overloaded or the mechanical part is stuck. In the auxiliary circuit, after the contactor coil circuit is energized, the armature does not pull in. It is necessary to distinguish whether it is caused by an open circuit or a stuck mechanical part of the contactor. You can press the start button. If there is a slight spark when the normally open contact of the button is disconnected from the closed position, it means that the circuit is in the path and the fault is in the mechanical part of the contactor; if there is no spark between the contacts, it means that the circuit is open.
Action procedures: The action procedures of automated production line equipment and electrical appliances should comply with the requirements of electrical instructions and drawings. If an electrical appliance on a certain circuit operates too early, too late or does not operate, it means that the circuit or electrical appliance is faulty. In addition, faults can also be determined based on the analysis of sound, temperature, pressure, smell, etc. emitted by electrical appliances. Using the intuitive method, not only can simple faults be determined, but more complex faults can also be reduced to a smaller scope.
2. Measuring voltage method
The voltage measurement method is based on the power supply mode of the automated production line equipment and appliances, measuring the voltage and current values at each point and comparing them with the normal values. Specifically, it can be divided into step measurement method, segment measurement method and point measurement method.
3. Resistance measurement method
It can be divided into step measurement method and segment measurement method. These two methods are suitable for electrical equipment with large distribution distances between switches and electrical appliances.
4. Comparison, replacement of components, and gradual opening (or access) method
1. Comparison method
Compare the test data with the drawings and normal parameters recorded in daily life to determine the fault. For electrical appliances with no data and no daily records, they can be compared with intact electrical appliances of the same model. When the electrical components in the circuit have the same control properties or multiple components jointly control the same equipment, the fault can be determined by using the actions of other similar components or the same power supply.
2. Method of placing conversion components
The cause of the fault of some circuits is difficult to determine or the inspection time is too long. However, in order to ensure the utilization of electrical equipment, components with good performance in the same phase can be switched for experiments to confirm whether the fault is caused by this electrical appliance. When using the conversion component method for inspection, it should be noted that after removing the original electrical appliance, carefully check whether it has been damaged. Only when the damage is definitely caused by the electrical appliance itself, can it be replaced with a new electrical appliance to prevent the new component from being damaged again.
3. Gradual opening (or access) method
When multiple branches are connected in parallel and a circuit with complex control is short-circuited or grounded, there will generally be obvious external manifestations, such as smoke and sparks. When the inside of the motor or the circuit with a shield is short-circuited or grounded, it is difficult to detect other external phenomena except the fuse blown. This situation can be checked using the gradual opening (or access) method.
Gradual opening method: When encountering a short circuit or ground fault that is difficult to check, the melt can be replaced, and the multi-branch cross-linked circuit can be disconnected from the circuit gradually or in key points, and then the power is turned on for a test. If the fuse blows repeatedly, The fault is on the circuit that was just disconnected. Then divide this branch into several sections and connect them to the circuit one by one. When a certain section of circuit is connected and the fuse blows again, the fault lies in this section of circuit and a certain electrical component. This method is simple, but it can easily completely burn out electrical components that are not seriously damaged. Gradual connection method: When a short circuit or ground fault occurs in the circuit, replace the fuses with new ones and gradually or focus on connecting each branch to the power supply one by one, and try again. When a certain section is connected, the fuse blows again, and the fault lies in the circuit just connected and the electrical components it contains.
4. Forced closure method
When queuing for electrical faults, if the fault point is not found after visual inspection and there is no appropriate instrument at hand to measure it, an insulating rod can be used to forcefully press the relevant relays, contactors, electromagnets, etc. with external force to make their normally open contacts Close it, and then observe various phenomena that occur in the electrical or mechanical parts, such as the motor never turning, the corresponding part of the automated production line equipment never moving to normal operation, etc.
5. Short circuit method
Faults in automated production line equipment circuits or electrical appliances can be roughly classified into six categories: short circuit, overload, open circuit, grounding, wiring errors, and electromagnetic and mechanical failure of electrical appliances. Among all kinds of faults, the most common ones are circuit break faults. It includes open wires, virtual connections, looseness, poor contact, virtual welding, false welding, blown fuses, etc.
In addition to using the resistance method and voltage method to check this type of fault, there is also a simpler and more feasible method, which is the short circuit method. The method is to use a well-insulated wire to short-circuit the suspected open circuit. If it is short-circuited somewhere and the circuit returns to normal, it means there is a circuit break. Specific operations can be divided into local short circuit method and long short circuit method.
The above inspection methods must be used flexibly and safety operating regulations must be followed. Components that are continuously burned out should be replaced after identifying the cause; the voltage drop of the wire should be taken into account when measuring voltage; it does not violate the principles of electrical control of automated production line equipment, hands must not leave the power switch during test run, and the insurance should be used, etc. The amount or slightly less than the rated current; pay attention to the selection of the gear of the measuring instrument.
Post time: Sep-08-2023