Login bg image My IET Expand
Contact us
 
IET
Decrease font size
Increase font size
 search :  help :  home
latest topics : statistics
Topic Title: 2395 Question Help please
Topic Summary: 2395 Written Zs Question Model answer please
Created On: 30 January 2013 01:14 PM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
30 January 2013 01:14 PM
User is offline View Users Profile Print this message



JJH

Posts: 1
Joined: 30 January 2013

Question ( worth 15 Marks )
Describe how a test for earth fault loop impedance, by direct measurement may be carried out on a circuit supplying a three-phase steamer .

My answer would be
I would not measure Zs on this circuit as it would contravene EAW Safe working practices. The value for Zs can be achieved without working near live conductors by R1+R2+Ze.

Comments :- I guess my answer would not get me 15 marks !

Can Anyone out there give me a Model answer to the question ? i.e. What are the examiners looking for ?

Thanks
Top : Bottom
08 February 2013 02:07 PM
User is offline View Users Profile Print this message



marclambert

Posts: 240
Joined: 23 June 2010

The clue is in "direct measurement" so it is a live test!
1 seek permission
1a signs/barriers
2 correct instrument and scale
3 calibration condition and operation
4 leads to GS 38
5 test between L1 - E
6 test L2 -E
7 Test L3 -E
8 record highest reading
9 reinstate circuit
10 compare readings to OSG or BS7671 corrected to 80%

No one really knows but that's a fair place to start I reckon.
regards
Marc
Top : Bottom
01 May 2013 04:31 PM
User is offline View Users Profile Print this message



saf

Posts: 36
Joined: 26 February 2009

Hi mate,

Im sitting my 2395 online assessment, soon ive been revising chapter 2 initial verification, 3 periodic inspection are they the two actual part i need to revise from...

ive done the online assessment practice my results are always coming up with 83% obvious im aimining full marks 100%, i just want tomake sure dispite getting reasonable results....is it enought to revise from the two sections only?


regards

surfraz
Top : Bottom
05 June 2013 09:09 AM
User is offline View Users Profile Print this message



drmiddleton1

Posts: 7
Joined: 15 March 2013

I did 2391, so can't help with what to revise.

But the answer from Marclambert is bob on. Also mention furthest point of circuit needs to be tested.

Remember, Zs on a live installation changes as opposed to Ze + R1 + R2, as you can have several parallel earth paths bringing down the Zs value.
Top : Bottom
05 June 2013 08:06 PM
User is offline View Users Profile Print this message



deapea

Posts: 365
Joined: 13 May 2007

I would mention about testing up to the live side of the contactor with the control circuit off as opposed to testing at the motor terminals.
Top : Bottom
05 June 2013 08:57 PM
User is offline View Users Profile Print this message



drmiddleton1

Posts: 7
Joined: 15 March 2013

Originally posted by: deapea

I would mention about testing up to the live side of the contactor with the control circuit off as opposed to testing at the motor terminals.


Yes, sorry. Contactor rather than the motor terminals.
Top : Bottom
IET » Student and apprentice discussion forum » 2395 Question Help please

Topic Tools Topic Tools
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2013 FuseTalk Inc. All rights reserved.


  • Facebook icon
  • Twitter icon
  • LinkedIn icon
  • YouTube icon
Back to top
Back to top

About the IET

Sectors we focus on

Useful links



Other IET Websites

IET

© 2013 The Institution of Engineering and Technology. The Institution of Engineering and Technology is registered as a Charity in England & Wales (no 211014) and Scotland (no SC038698)