NVQ help | on ElectriciansForums

Discuss NVQ help in the Electrical Course Trainees Only area at ElectriciansForums.net

S

Sparkypid

hi,

ive forgotten my old login so have made a new one,

i was was originally on here when I first started my apprenticeship, I'm nearly done now but im after some help.

Im on the testing and inspection part and because I can't find all the faults on site if any, I have to say if I found them this is how I would diagnose it

loss of supply
overload
short-circuit and earth fault
transient voltage
loss of phase/line
incorrect phase rotation
high resistance joints
component, accessory or equipment faults

I'm after some info on how to find these faults so I can explain it for my nvq,

any help ell would be appreciated.

doesnt anyone have an exactly list in what you need to do on the am2?

thanks paul
 
I'm still doing my level 2 so I'm not much help, there are a couple of guys who have just done the am2 who would be able to help though, if you drop Ste69 a pm he will have some info, he also has a thread a bit further down the page you could post in called 'am2 results'
 
I'm having a full day on my NVQ today.

This is is what I've written for each thing, I'm not really clued up that well on testing, it seems unfair to make you write up about things that, you need specific training to do. And my firm doesn't do loads of testing so it's limited on what I can do.

Can anyone tell me if what I have written is anything close cheers

[ElectriciansForums.net] NVQ help

[ElectriciansForums.net] NVQ help

[ElectriciansForums.net] NVQ help

thanks.
 
Well done , you have made a determined effort to think about the problems and how you would go about resolving them.
Definitely worthy of support I feel.

Just my thoughts on what and how you may be able to approach this.

Always remember what training you have undergone.
Use approved terminology wherever possible, make a point of ensuring the you are working dead at all times, minimise the live testing required.
Always work logically in a fault diagnosis situation.
Consider the circuit design and function to ensure you know what items you are testing and why you are testing. Also you should be aware of the nature and range of values you expect to find and the units in which those values are measured.

Loss of supply.

This is rather wide ranging and could cover local or installation wide loss of supply.
An initial practical assessment of items of functional equipment could indicate the range of the loss of supply.
If the entire installation has lost power then a test for voltage with an approved voltage tester at the closest accessible point to the incoming supply should indicate if the fault lies with the supply equipment or the installation equipment.
If a protective device has operated this should be, on a well designed system, the closest protective device to the fault.
Depending of the type of protective device the testing on the safely isolated circuit may be low ohm continuity to determine a short circuit fault or an overload fault where a circuit breaker has tripped, or insulation resistance testing, possibly followed by low ohm continuity testing, to determine an earth fault where an RCD has tripped.

Testing continuity across the main fuse would require breaking of security seals for the DNOs equipment and would be an offence.
Resetting or replacing a protective device before resolving the fault would be generally a futile exercise and may be considerably dangerous.

Overload

Where a circuit breaker has tripped due to overcurrent an initial assessment of the load of connected equipment may permit an initial diagnosis. Failing that a low ohm continuity test on the safely isolated circuit between line and neutral would allow calculation of the expected current draw using I=V/R. Further splitting the circuit in stages sand testing would narrow down the area to the point of the fault. It should be noted that electronic equipment may give a false indicating of the connected load.

Your answer was good though fairly informal and lacking detail on the nature of “all test results” you were performing on the circuit. The example is a good touch though most MCBs do not come in 5A any more.

Short circuit and earth fault

I believe this would mean faults of negligible impedance between line and neutral or between line and earth (or both).
Testing of the safely isolated circuit with a low ohm continuity tester and splitting down the circuit logically and testing would narrow down the area to the point of the fault.

If earth faults means a sufficiently low resistance to permit an RCD to trip then this may be possible to determine with a suitably accurate insulation resistance tester, loose terminations could cause short circuits if the cable had become removed from the terminal, reversed polarity would not normally cause short circuits but would generate a dangerous situation by leaving equipment live when switched off.

Transient voltage

Often a high transient voltage generated from electronic equipment generating harmonic currents or unstable voltage conditions, supply network faults, high voltage atmospheric conditions or rapid heavy load switching (that can also cause transient low voltage on the supply).
A data logger may be employed to determine voltage transients experienced over time and by the speed and regularity of the transients may permit a diagnosis of the cause.

Loss of phase / line

Los of line in a single phase system will be similar to loss of supply.
Loss of a single phase in a three phase system can be indicated by motor faults, poor or none existent stating and irregularity in operation. Voltage testing using a suitable volt meter with probes meeting GS38 requirements to determine to voltage at each phase should identify the faulty phase, or continuity tests on a safely isolated circuit can identify the break point in a line conductor.

Overall good answer

Incorrect phase rotation can be identified as it can cause motors to run in reverse.
I test with a phase rotation tester at the supply and load ends of a circuit can confirm incorrect phase rotation. If the circuit is safely isolated then a low ohm continuity cheek of the line conductors from supply to load can identify reversed phases.

A good answer perhaps slightly specific to the equipment you have, but correct.

High resistance joints

High resistance joints are characterised by an increased temperature at the point of resistance due to power dissipation in the resistance and in severe cases heat damage and burning of the accessorises and cables, which may then be identified by sight and smell.
Use of thermo graphic surveying may indentify such areas of increased temperature and logical staged measurement of low ohm continuity on a safely isolated circuit will also permit identification of the pint of the fault.

If you are doing R1+R2 testing or end to end resistance on ring final circuits then these problems should come to light, but may not be part of general diagnosis techniques. Correct use of a low ohm continuity tester to identify.


Component, accessory or equipment failure

Component, accessory or equipment faults can be indentified by loss of power and / or intermittent or uncharacteristic operation of equipment.
Total loss of power to equipment can be narrowed down to the point of fault by the use of voltage indicating equipment, suitable for the supply voltage, at accessible points on the supply route up to the equipment.
Monitoring or receiving accurate reports of the nature and frequency of intermittent or uncharacteristic operations can give an indication of the type and location of the fault.
Component or equipment failure can be determined by a logical step by step approach that is dependent on the nature of the equipment and the manufacturers instructions. Wherever possible diagnosis techniques should be restricted to work on safely isolated equipment.

Some useful examples in your answer and visual inspection is often a very simple and clear cut method of fault finding.

I should stress that these are only my off the cuff thoughts about possible ways of responding not approved answers and not necessarily correct, particular requirements or items on which you have been trained could well override these thoughts.
Someone closer to training may have better ideas

Thinking is also a good method of fault diagnosis!!!
 
Hi Im coming to the end of my second year as an apprentice in college and we have only had about 2 NVQ lessons. I have gathered quite a lot of evidence as in pics and I have answered most of the questions. I was just wondering if there are any other threads on NVQ work as I am stuck now. thanks
 
Well done , you have made a determined effort to think about the problems and how you would go about resolving them.
Definitely worthy of support I feel.

Just my thoughts on what and how you may be able to approach this.

Always remember what training you have undergone.
Use approved terminology wherever possible, make a point of ensuring the you are working dead at all times, minimise the live testing required.
Always work logically in a fault diagnosis situation.
Consider the circuit design and function to ensure you know what items you are testing and why you are testing. Also you should be aware of the nature and range of values you expect to find and the units in which those values are measured.

Loss of supply.

This is rather wide ranging and could cover local or installation wide loss of supply.
An initial practical assessment of items of functional equipment could indicate the range of the loss of supply.
If the entire installation has lost power then a test for voltage with an approved voltage tester at the closest accessible point to the incoming supply should indicate if the fault lies with the supply equipment or the installation equipment.
If a protective device has operated this should be, on a well designed system, the closest protective device to the fault.
Depending of the type of protective device the testing on the safely isolated circuit may be low ohm continuity to determine a short circuit fault or an overload fault where a circuit breaker has tripped, or insulation resistance testing, possibly followed by low ohm continuity testing, to determine an earth fault where an RCD has tripped.

Testing continuity across the main fuse would require breaking of security seals for the DNOs equipment and would be an offence.
Resetting or replacing a protective device before resolving the fault would be generally a futile exercise and may be considerably dangerous.

Overload

Where a circuit breaker has tripped due to overcurrent an initial assessment of the load of connected equipment may permit an initial diagnosis. Failing that a low ohm continuity test on the safely isolated circuit between line and neutral would allow calculation of the expected current draw using I=V/R. Further splitting the circuit in stages sand testing would narrow down the area to the point of the fault. It should be noted that electronic equipment may give a false indicating of the connected load.

Your answer was good though fairly informal and lacking detail on the nature of “all test results” you were performing on the circuit. The example is a good touch though most MCBs do not come in 5A any more.

Short circuit and earth fault

I believe this would mean faults of negligible impedance between line and neutral or between line and earth (or both).
Testing of the safely isolated circuit with a low ohm continuity tester and splitting down the circuit logically and testing would narrow down the area to the point of the fault.

If earth faults means a sufficiently low resistance to permit an RCD to trip then this may be possible to determine with a suitably accurate insulation resistance tester, loose terminations could cause short circuits if the cable had become removed from the terminal, reversed polarity would not normally cause short circuits but would generate a dangerous situation by leaving equipment live when switched off.

Transient voltage

Often a high transient voltage generated from electronic equipment generating harmonic currents or unstable voltage conditions, supply network faults, high voltage atmospheric conditions or rapid heavy load switching (that can also cause transient low voltage on the supply).
A data logger may be employed to determine voltage transients experienced over time and by the speed and regularity of the transients may permit a diagnosis of the cause.

Loss of phase / line

Los of line in a single phase system will be similar to loss of supply.
Loss of a single phase in a three phase system can be indicated by motor faults, poor or none existent stating and irregularity in operation. Voltage testing using a suitable volt meter with probes meeting GS38 requirements to determine to voltage at each phase should identify the faulty phase, or continuity tests on a safely isolated circuit can identify the break point in a line conductor.

Overall good answer

Incorrect phase rotation can be identified as it can cause motors to run in reverse.
I test with a phase rotation tester at the supply and load ends of a circuit can confirm incorrect phase rotation. If the circuit is safely isolated then a low ohm continuity cheek of the line conductors from supply to load can identify reversed phases.

A good answer perhaps slightly specific to the equipment you have, but correct.

High resistance joints

High resistance joints are characterised by an increased temperature at the point of resistance due to power dissipation in the resistance and in severe cases heat damage and burning of the accessorises and cables, which may then be identified by sight and smell.
Use of thermo graphic surveying may indentify such areas of increased temperature and logical staged measurement of low ohm continuity on a safely isolated circuit will also permit identification of the pint of the fault.

If you are doing R1+R2 testing or end to end resistance on ring final circuits then these problems should come to light, but may not be part of general diagnosis techniques. Correct use of a low ohm continuity tester to identify.


Component, accessory or equipment failure

Component, accessory or equipment faults can be indentified by loss of power and / or intermittent or uncharacteristic operation of equipment.
Total loss of power to equipment can be narrowed down to the point of fault by the use of voltage indicating equipment, suitable for the supply voltage, at accessible points on the supply route up to the equipment.
Monitoring or receiving accurate reports of the nature and frequency of intermittent or uncharacteristic operations can give an indication of the type and location of the fault.
Component or equipment failure can be determined by a logical step by step approach that is dependent on the nature of the equipment and the manufacturers instructions. Wherever possible diagnosis techniques should be restricted to work on safely isolated equipment.

Some useful examples in your answer and visual inspection is often a very simple and clear cut method of fault finding.

I should stress that these are only my off the cuff thoughts about possible ways of responding not approved answers and not necessarily correct, particular requirements or items on which you have been trained could well override these thoughts.
Someone closer to training may have better ideas

Thinking is also a good method of fault diagnosis!!!

Well said Rich, one thing though, probably a bit of a jobs worth, but should it not be Phase Sequence as opposed to Rotation, I seem to recall someone else mentioning that but can't remember where.
 

Reply to NVQ help in the Electrical Course Trainees Only area at ElectriciansForums.net

News and Offers from Sponsors

  • Article
Join us at electronica 2024 in Munich! Since 1964, electronica has been the premier event for technology enthusiasts and industry professionals...
    • Like
Replies
0
Views
669
  • Sticky
  • Article
Good to know thanks, one can never have enough places to source parts from!
Replies
4
Views
1K
  • Article
OFFICIAL SPONSORS These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then...
Replies
0
Views
2K

Similar threads

Hi all, I’m in the final stage of my electrical apprenticeship and I need some help to complete my portfolio. I have all units apart from 115...
Replies
0
Views
102
Thanks for your advice bud, I actually spoke to a Gold Card holder over the weekend of whom gave me the same advice
Replies
2
Views
536

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
Back
Top