1. Fault location and Diagnosis

2. Preparation for fault diagnosis
Access: have all obstructions been removed? Inspection covers?, Clutter? Signs barriers are in place
Visibility: has dust, grease and dirt been cleaned to reveal as much as possible of the job in hand?
Symptoms: do you understand the nature of the problem? What is that the equipment has failed to do? How is the performance abnormal?

3. Now eliminate
the obvious

4. Method Collect the evidence Approach with an open mind
Before disturbing or changing anything- Stop, Look, Listen and Learn
Collect only relevant information, if in doubt about its validity include it and discard later if unrelated
Question the user
Check the system running if possible
Use sources of information, manuals, maintenance records etc
Use test equipment to verify calibration and settings
Analyse the evidence
separate the various symptoms and work out the importance of each one
Check if the evidence leads to a previously recorded fault
3. Locate the Fault
Use all resources available- test equipment etc
If possible locate fault to component level
Never assume- always remove and check suspect components

5. Determine and Remove the Root cause
The root cause of the fault must be located and removed otherwise the fault will eventually reoccur
Rectify the Fault
Any adjustment, repair or replacement should only be carried after identifying and removing the root cause of the problem
Test the System
Ensure the machine, equipment or system is functioning correctly before being put back into service- fine tune if required

6. Identify the cause Symptom (overheating) Fault (worn bearing)
Symptom - signs or indications that there is a deviation from the normal operating mode
Fault – the particular defect or combination of defects that cause the symptom to occur
Cause – the reason why a fault has occurred
Symptom (overheating)
Fault (worn bearing)
Cause (poor lubrication)

7. Sensory (visual)
fractures, surface cracks, corrosion, leaks, damage, contaminated oils, Loose fastenings, excessive wear, metallic particles, broken chains and belts, missing parts

8. Sensory (smell)
Smell- hot oil, burnt out motor, burnt out belts, overheating

9. Sensory (Touch)
Touch- vibration, wear, play, belt or chain tension, out of balance, excessive clearance

10. Sensory (Noise)
Noise- unfamiliar noises , out of balance, vibration, worn bearings, air leaks

11. Six Point Technique - Used on complex faults with a history of data
Observe machine running (if safe to do so)
Use test equipment (built in or otherwise)
Refer to manufacturers manual (look for fault finding aids)
Use sensory techniques
1. Collect the Evidence
Consider machine history records
Question the operator (use good social skills)
Consider
Packaging materials
Raw materials
Services (air water etc)
2. Analyse the evidence (diagnosis)

12. 3. Locate the Fault (based on analysis of evidence)
4. Determine and remove cause
(to prevent reoccurrence)
5. Rectify the fault
6. Check the machine or system (before handing over to production)

13. Emergent Problem Sequence
In any equipment failure there are factors that have caused a deviation from the normal
mode of operation (changed factors)
Sequence
Analysis: determine the real problem or problems
Prioritise: seriousness, urgency, the expected outcome
Statement: write down the problem or variance
Describe the problem
Where – geographically or on the object
What- object or defect
When- time or life cycle
Size- how big-how much-how many

14. Set Boundaries - use the description to narrow down the field of investigation
Differences- look for factors that are unique to the problem
Identify – changed factors
Diagnose – list and categorise each changed factor in terms of which it explains the facts
Ask yourself
Is there a deviation from the standard or norm?
Is the cause unknown?
Do I need to know the cause?
Do I need to be involved?
If all points are answered ‘Yes’ then use the six point technique

15. Half Split Technique fault 3rd check signal ok 1st check signal ok
This is used to reduce diagnosis time in circumstances where a series of components are
working together. It is based on the process of iteration. This simply means narrowing
down and revisiting
fault
3rd check signal ok
1st check signal ok
2nd check no signal

16. Function Testing
There is normally a specification for the operation of an electrical component,
equipment or system. By ensuring the outputs are connected correctly and the
correct input is applied, the operation or function of the electrical equipment can be
measured against the specification. Does it do what it designed to do within the
given parameters? If not then it is faulty
Input (240v) ok
Output (heater) not heating up – heater is at fault

17. Input to Output Technique
If the required function is known, and the input and output can be measured, then the
location of the fault is narrowed down or found
Inputs
Output x A B
Output y C

18. Unit Substitution
If the input and output from a functional component can not be measured, a method of
fault location is to replace each component in turn, useful where components are easily
substituted with a known functioning unit
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19. Diagnostic Aids Equipment manuals Valuable source of information
Most manuals will include a section that is dedicated to the tracing of faults. It will usually be in the format that describes the symptoms, the possible faults that have caused the symptoms and the appropriate remedial actions

20. Algorithms Action Question Direction Stop
A step-by-step problem-solving procedure, for solving a problem in a finite number of steps.

21. Self Diagnostics
Many Modern Machines especially production and processing equipment, are equipped with self-diagnosis panels. They come in a variety of forms but they usually have a visual representation of the system.
The elements of the system that may fail have a sensor that checks for correct operation

22. Maintenance/Equipment Records/CMMS
It is imperative that any information relating to the equipment or system is recorded so
as aid future maintenance and continual improvement
Records can be in:
Technical Files or Maintenance logs – written or electronic
Recent trends have seen the introduction of software packages that are designed to hold
and access equipment history (Computer Maintenance Management Systems)
All Records should include:
Breakdowns (fault, cause and remedy)
Planned Maintenance (work done)
Condition monitoring results

23. Computer Maintenance Management Systems
Using software packages will:
Reduce maintenance cost
Optimise inventory and purchasing
Implement standards and compliance
Store and retrieve records
Improve maintenance management program reliability