1. EKAS 2.19.28 Fault find- General Principles
UEE31307 Certificate III in
Refrigeration and Air Conditioning
Stage 2A
Units: UEENEEPOO1B
Chris Hungerford
Wednesday, April 19, 2017

2. The two golden rules
Test before you touch, this protects you physically, so you can have a good day!
Test your work is electrically safe when completed, tests include insulation resistance, earth continuity, polarity, and visual inspection, this protects you financially. A

3. Procedure to isolate a Supply
Safe Isolation of a Supply
Test before you touch, this protects you physically, so you can have a good day!
Procedure to isolate a Supply
Notify all persons likely to be affected by the isolation.
Determine the method to isolating the supply.
Test the supply availability.
Isolate the supply.
Danger tag the isolation device.
Test that the supply is isolated.
Test the testing device. A

4. Electrical Safety Regulation 2002
WARNING
Are you working LIVE? Using a voltmeter to measure low voltage is working live!
Electrical Safety Regulation 2002
11 Requirements for electrical work
(1) An employer or self-employed person must ensure that, unless the circumstances required under this division for the performance of live work apply, live work is not performed.
Maximum penalty—40 penalty units.
As per Regulation 12 “Requirement for performance of live work”, to perform live work you must satisfy the following seven (7) questions:
Have you prepared a risk assessment?
Is your test equipment appropriate to perform live work? Minimum Cat 500v ac.
Has your test equipment been maintained and confirmed that it is operating correctly? Regulation 18.2(b) “the instrument is tested at least every 6 mths to ensure it is in proper working order”, and Regulation 12.1(f) “the instrument is tested immediately prior to work to confirm that the instrument is operating correctly”
Have you the correct PPE, (Safety boots, long pants, long sleeved shirt, insulated gloves, safety glasses)? As per AS/NZS 4836 Safe working on low voltage electrical installations.
Is the isolation point clearly identified?
Is the isolation point able to be reached without any obstructions?
Is the area where the electrical live work is performed clear of any obstructions?
Note: if you are not working within the requirements of the above laws then your inaction to comply threatens the following;
Your right to claim workcover in the event of an accident
Your right to claim any insurance benefits in the event of an accident
You will be fined the prescribed penalty units for those laws that you have breached. A

5. What is a Fault?
Any condition in an electrical system that is dangerous or unsafe is a fault.
Any condition that will prevent the electrical system from operating correctly is a fault. B

6. Overload An overload is a condition where the load on the circuit is too much, causing the current to exceed the current rating of the cables and supply. If the excessive current was allowed to continue, the cables would heat above their rating and may lead to a short circuit.
6A fuse
6A fuse
Load
48
240v
240v
48
48
I = V = = 5A R
I = V = = A R B

7. Short circuit, A very severe condition and will cause fire, burns, and equipment damage if not protected against. The only resistance to the current is that of the supply cables and the size of the electrical source.
short circuit
0.5
cables = 0.5
cables = 0.5
Load
47.5
Load
48
240v, 500A
supply
240v, 500A
supply
I = V = = 5A
R ( )
I = V = = A
R (.5+.5)
8A fuse
short circuit
0.5
240v, 500A
supply
The fuse will open circuit when
the current exceeds it’s rating. B

8. Partial open circuit, (hot joint) caused by loose or dirty connections that causes an increased circuit resistance. This increased resistance causes a heating effect at the joint and reduces the current at the load. Will cause fire and equipment damage. A fuse or circuit breaker will not protect against this type of fault. The only combat is by visual inspections or thermal imageries.
12
P=I R = 4 *12 = 192W 2 2
P=V*I
=240 *5
= 1200W
48
48
240v
240v
P=I *R =4 *48=768W 2 2
I = V = = 5A R
I = V = = 4A
R (12+48) B

9. Partial short circuit. Like a short circuit with a higher resistance
Partial short circuit Like a short circuit with a higher resistance. Normally earth faults. Fuses and circuit breakers may not open circuit if the fault current does not exceed their rating. Earth leakages are good examples.
6A fuse
6A fuse 2A 5A
Load
48
240v
120
48
240v
I = V = = 7A R
I = V = = 5A R B

10. short circuit or overload short circuit or overload
Procedures for fault finding
Voltage
Present
Not present
Measure
current
Measure
resistance
No current
High current
Low current
Low
resistance
Very low
resistance
Measure
resistance
Open
circuit
Short
circuit
Partial
short circuit or overload
Partial
open circuit
Partial
short circuit or overload B

11. Flowchart For Problem Resolution
Is It Working? NO
YES
Don’t Stuff With It!
Did You Stuff
With It?
YES
YOU IDIOT! NO
Anyone Else
Know?
Will it Blow Up
In Your Hands?
YES
You’re SCREWED!
YES
Can You Blame
Someone Else? NO NO NO
Hide It
Look The Other Way
Yes
NO PROBLEM!

12. Common sense ways to think of categories
Overvoltage category
Common sense ways to think of categories
The higher the short circuit fault current available, the higher the category
High energy transients are much more dangerous, because they can trigger an arc blast
The greater the source impedance, the lower the category
Electricians are accustomed to thinking in terms of short circuit currents because one of the key specifications for circuit breakers and fuses is their kAIC rating. KAIC stands for kilo-amps interrupting capacity-the kilo-amps of fault current that will be safely interrupted.
Source impedance refers to the total impedance between the load and the source, including the impedance of the wiring. The greater the distance, the greater the impedance.
The TVSS (transient voltage surge suppressor) industry has by necessity done a good deal of customer education on this issue. In brief, it is evident that a surge suppressor installed at a service entrance, or at a load panel or at the outlet will be required to survive much different energy levels. B

13. This meter had the original fuse replaced with an automotive fuse
This meter had the original fuse replaced with an automotive fuse. When the operator attempted to measure 480 volts with the leads in the amps inputs, the fuse offered no protection. It is better to leave the circuit unfused and open than to use the wrong fuse.
Note that the test leads and probes, though damaged, survived more or less intact. This fact, plus the mechanical ruggedness of the meter body, which helped to contain the explosion, contributed to the fact that the operator was not hurt. B

14. What’s the bottom line?
If you work on power circuits, you need a CAT III-600 V or CAT IV-600 V/ CAT III 1000 V meter.
Look for the CAT rating and voltage rating marked near the input jacks.
CAT or voltage rating alone can be misleading
Look for independent certification.
Some manufacturers mark their meters as CAT III-750 V. The IEC standard does not allow spacing in between 600 V and 1000 V; i.e., a meter can only “meet” CAT III-750 V by meeting CAT III-1000 V, in which case any manufacturer would presumably mark it CAT III-1000 V. Some manufacturer’s meters have 1000 V marked on the front, with no reference to CAT I, II or III. Only on the back and in the manual does it become clear that the meter is CAT I V (it is dual rated as CAT III-300 V). It is fair to say that there appears to be some “confusion” among manufacturers with regard to these relatively new standards., which is why it is important for you to educate yourself with regard to the new safety standards.
CAT IV-600 V CAT III-1000 V B

15. Fault finding: Continuity technique
Warning: Disconnect the supply.
All healthy component’s circuit have a value of resistance.
Placing an ohmmeter across the component should indicate the components condition.
Values of 0W are considered as short circuited.
Values of infinite ohms are considered as open circuited. B

16. Fault finding: Supply available technique
Low voltage is present therefore Regulation 12 ESR2002 must be satisfied before working live.
Voltmeter set to highest scale
Place voltmeter across the circuit with supply available:
the voltmeter should indicate the supply if healthy.
If the voltmeter does not indicate the supply then search across the circuit devices for the voltage.
contactor
T=25deg C
T/O
HP/LP
A 240V N A1 A2
Voltmeter should indicate 240v if healthy B

17. NO supply indicated by the voltmeter, be careful,
contactor
T=25deg C
T/O
HP/LP
A 240V N A1 A2
Voltmeter = 0v
NO supply indicated by the voltmeter, be careful,
just because the voltmeter does not indicate any voltage does not mean there is no voltage present, the voltage difference across the across the HP/LP is zero. It could be 240v each side of the HP/LP therefore the difference is zero. B

18. Voltmeter=0v, the fault has not shown itself.
contactor
T=25deg C
T/O
HP/LP
A 240V N A1 A2
Voltmeter = 0v
Voltmeter=0v, the fault has not shown itself. B

19. Voltmeter=240v, the fault has shown itself.
contactor
T=25deg C
T/O
HP/LP
A 240V N A1 A2
Voltmeter = 240v
Voltmeter=240v, the fault has shown itself.
A healthy circuit the voltage should be 0v across a closed switch. This voltmeter indicates a difference therefore the T/O is defective. B

20. T=25deg C T/O HP/LP Voltmeter = 180v 2.19.28.B contactor A 240V N A1

21. Voltmeter = 180v, therefore the circuit between HP/LP to A1 is OK.
contactor
T=25deg C
T/O
HP/LP
A 240V N A1 A2
Voltmeter = 180v
Voltmeter = 180v, therefore the circuit between HP/LP to A1 is OK. B

22. T=25deg C T/O HP/LP Voltmeter = 240v
contactor
T=25deg C
T/O
HP/LP
A 240V N A1 A2
Voltmeter = 240v
Voltmeter = 240v, and 180v as before, therefore, the problem must be across the HP/LP. B

23. T=25deg C T/O HP/LP Voltmeter = 60v Voltmeter = 180v
contactor
T=25deg C
T/O
HP/LP
A 240V N A1 A2
Voltmeter = 60v
Voltmeter = 180v
The Voltmeter across the HP/LP should be equal to 0v as the resistance of a closed switch should be as close to zero ohms.
The voltmeter indicates an elevated voltage (60v) therefore there must be an elevated resistance, i.e. high resistance. B

24. Work Record required by Regulations
Electrical Safety Regulation 2002
Part 2 Electrical work
14 Testing of electrical equipment after electrical work
(1) This section applies if electrical work is performed on electrical equipment.
(2) A person who performs part or all of the electrical work, and is responsible for bringing the electrical equipment to a state of readiness for connection to a source of electricity for use for its intended purpose, must ensure the electrical equipment is tested, as required under subsections (5) and (6).
Maximum penalty—40 penalty units. .
Date of inspection
Appliance
Visual inspection
Earth continuity W
Insulation resistance MW
Polaritya = Correct
RCD test current
30 MA trip time
Milliseconds
0h h Test butt
2/7/09
Refrigerator ( LG model R Serial )
O.K
0.3
75M
N/A
Safetypac (Clipsal mod 56B, serial )
o.K.
0.8
187M a 22 18 B

25. Work Record required by Regulations
Electrical Safety Regulation 2002 Part 2 Electrical work
15 Certificate of testing and safety
This section applies if a licensed electrical contractor performs electrical work that must be tested under this division.
(2) The contractor must, as soon as practicable after the testing, ensure that the person for whom the electrical work was performed is given a certificate complying with this section.
(5) A licensed electrical contractor must keep a copy of a certificate given under this section for at least 5 years after the certificate is given.
Maximum penalty for subsection (5)—20 penalty units
Certificate of Testing and Safety
As per Electricity Safety Regulation 2002,Part 8”Electricity Supply”, Division 3 “Testing”, Regulation 159,”Certificate of Testing & Work”
Electrical worker who tested the electrical work.
Phone
Licence No:
Contractors Licence
Details of work
Details of Electrical Contractor
Inspection Certificate No:
Acts, Regulations,
Codes of Practices & Standards.
Electricity Act 1994 & Electricity Regulation 2006
Electrical Safety Act 2002 & Electrical Safety Regulation 2002
AS/NZS 3000:2000. Incorporating Amendment No. 1 (September 2001), Amendment No. 2 (April 2002), & Amendment No. 3 (July 2003). The Wiring Rules.
AS/NZS :1998, Electrical installations— Selection of cables Part 1.1: Cables for alternating voltages up to and including 0.6/1 kV—Typical Australian installation conditions
I certify that the electrical installation work listed above has been tested in accordance with the prescribed procedures and that such work is electrically safe and complies in every respect with the requirement of the Electricity Safety Regulation 2002, regulation 159.
Signature of Electrical worker:
Date of Certification: B

26. Manufacturer Specifications of disconnected & replacement equipment.
When replacing any load you should be sure that the new item is suitable with regards to: Speed, Rotation, Power rating, Voltage, Current, Physical size, Environmental conditions & design of replacement, Dust & waterproof, temperature, UV rating, touch proof, life span. C

27. Energising supply
Only after the visual inspections and safety testing as per AS/NZS 3000:2007 has proven that the circuit is fit for purpose are you to energise the circuit.
Remove only your Danger tag. If another worker has their danger tag on the isolated point then you can not energise.
If clear: Energise the circuit.
Test for the correct and safe operation of the circuit, i.e. rotation, system performance, current draw, voltage, etc.
Prepare all your safety and performance documentation. C