Exams for apprentices

I am afraid that as an instructor I was unable to answer with confidence the followig simple questions that appeared on a recent apprentice exam!!! Perhaps you might be able to ease my embarrassment!
1 The substation layout that requires a bus coupler cb is a;
(a) three switch
(b) sectionalised single bus-bar
(c) double busbar
(d) horseshoe busbar

2 The tension which overhead line conductors impose on terminal backstays is determined by the
(a) transverse load
(b) longtitudinal load
(c) ultimate tensile stress
(d) factor of safety

3 In the making of an impregnated pressure cable joint the core screens are;
(a) terminated at each end
(b) bonded to the lead sheath
(c) made off with flares and lead wire
(d) made continuous through the length

4 An expansion joint is used in some types of high voltage undergroun cables to counteract the effect of;
(a) excessive oil pressure
(b) load surges
(c) increased loading
(d) subsidence

Appreciate any effort.

 

[busbar]

4-c maybe? What country is the exam given in?

 

[tgott]

My best guesses: 1.b 2.b 3.d 4.a

 

[lyledunn]

Busbar,

exam is UK

Thank you tgott, I think 1.c 2.b 3.d 4.d

 

[tgott]

Lyledunn: The terminology is different than what I am used to in the US. I almost went with c for 1, but after looking at the RUS design guide

http://www.usda.gov/rus/electric/pubs/1724e300/1724e300.pdf

(page 132) went with b. For 2 I think we usually call backstays deadends. Longitudinal load is parallel to the conductor, tranverse loading is perpendicular to the conductor. So I'm pretty sure we're right on that one. I'm really not too familiar with underground cable, so 3 was purely a guess. The word "core" made me think it should be continuous through the whole length. On number 4, I know about expansion joints used on conduits and agree with your answer in that regard. The question as posed led me to believe it was an oil-filled cable and I seem to remember a web page about a type of conservator tank to insure the pressure remained constant. However, now after looking at

http://www93.thomasregister.com/ss/... and cable&wherefrom=&pdm=&json=y&indexpage=y

I think that busbar might be correct with the answer c of increased loading causing increased heating leading to thermal expansion.
So there ya are. Now back to my load flow studies!