In fault analysis, certain procedures should be followed, which are roughly as follows:
First, in the case of keeping the scene for symptom analysis.
(1) Ask the operator: What's wrong? Under what circumstances and when did it happen? How long has the equipment been running? Is there any abnormal phenomenon (such as noise, alarm signal, smoke and peculiar smell) before the failure, and is there any wrong operation? Is the control system operating normally? Is there any change in operating procedures? Are there any special difficulties or anomalies during operation?
(2) Observe (including the general situation of the whole machine and various operating parameters) to see if there are any obvious anomalies? Is the part jammed or damaged? Are all kinds of pipelines loose or leaking? Is the cable (wire) broken, scratched or burned? What are the changes in equipment operation parameters? Is there any obvious damage signal?
(3) check the detection index device
Check whether all readings are normal, including pressure or instrument readings. Check whether the filter, alarm and interlock device, printout or display are normal.
(4) Inspection of inching equipment (if conditions permit)
Check the intermittent conditions, long-term conditions, fast or slow conditions, whether these conditions are representative and reproducible, whether they affect the output, and whether they can cause damage or other dangers.
Second, check the equipment (including parts, components, system circuit inspection)
(1) Use the five senses to check (continue the process of in-depth observation)
Touch: the heat of vibration components (groups) of the equipment (pay attention to safety! Try to use the back of your hand).
Listen: Is there any abnormal sound?
Smell: whether there is burnt smell or other peculiar smell;
Check: switch and position change of workpiece, change of equipment performance parameters, abnormal line inspection.
When conducting line inspection, it should be carried out under the specific conditions of clear system principle and familiarity with system wiring and installation street.
When conducting line inspection, it should be carried out under the specific conditions of clear system principle and familiarity with system wiring and installation street.
(2) Evaluate the inspection results
Evaluate whether the fault judgment is correct, whether the fault clues are found, and whether the inspection results are consistent.
Third, the determination of fault location
(1) Determine the system structure and test method.
After being familiar with the equipment manual and understanding the basic principle of the equipment, determine the fault of the equipment, and make clear what method to test, what manual test means are needed, what test parameters or performance parameters may be obtained, under what operating conditions, what safety measures must be observed, etc.
(2) System inspection
According to the previous analysis, adopt the most appropriate measurement method, select the appropriate measurement point, and determine the suspicious location according to the input or feedback results and normal values or performance standards.
There are many methods for system detection, such as direct comparison method (compared with fault-free equipment), step-by-step isolation method (gradually narrowing the scope of inspection), transformation condition method (used when the fault phenomenon is not obvious), trial reduction to absurdity, detection quantity method, trial cutting sample method and so on.
Four, repair or replacement
(1) Repair: find out the cause of failure, repair and take preventive measures; Check the related parts to prevent the fault from spreading.
(2) Replacement: correctly assemble and debug replacement parts, and pay attention to related parts.
Five, Conduct performance measurement.
(1) Start the equipment, after debugging and assembling, run it manually (or inching) first, then automatically (or continuously), then run it with no load and then run it with load for determination.
(2) Adjust the load change, and test the speed from low to high and the load from small to large.
(3) Expand the scope of performance test, and gradually expand the scope of performance test from local to system according to needs, and pay attention to the operation status of the system in the non-fault area. If the performance meets the requirements, it will be delivered for use. If it cannot meet the requirements, the fault position will be re-determined.
