Test question

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nickelec

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Can anyone tell me what does v stand for when a battery reaches end of charge

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Also having some trouble with this
Calculate the amperages rating for a copper bus bar 3" wide by 1¼ thick

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Corrected


Calculate the amperages rating for a copper bus bar 3" wide by ¼ thick

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nickelec said:
Corrected


Calculate the amperages rating for a copper bus bar 3" wide by ¼ thick
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Not sure if this helps but this is from the NYC electrical code.

(E) Busbars.
(1) General. Busbars shall be sized based on 1000 amperes per square inch for copper and 750 amperes
per square inch for aluminum.
Exception: In service switchboards, generator paralleling switchboards and when connecting to devices
rated over 2500 amperes. See 408.60(E)(2) and (E)(3) below.
(2) In Service Equipment And Switchboards Supplied Directly From Separately Derived Systems.
Line-side busbars in service switchboards and all busbars in generator paralleling switchboards shall be
considered service conductors and shall comply with the requirements of 230.42(A).
(3) Connection to Devices Rated over 2500 Amperes. Busbars shall be sized in accordance with (a)
and (b) below when connected to a device (switch or circuit breaker) over 2500 amperes:
(a) Over 2500 amperes but less than 5000 amperes, busbars shall be sized based on 800 amperes
per square inch for copper and 600 amperes per square inch for aluminum.
(b) 5000 amperes and over, busbars shall be sized based on 700 amperes per square inch for
copper and 525 amperes per square inch for aluminum.
Exception: Beyond a minimum distance of 1.2m (4 ft) along the current path from the device, the busbar
may be reduced in size, in accordance with 408.60(E)(1) above.
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Where do u get 4" from and isn't it 1000 multiplier not 750? 750 is for aluminum is it not?

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nickelec said:
Where do u get 4" from and isn't it 1000 multiplier not 750? 750 is for aluminum is it not?
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Again this is using my previous information which stated this:

(E) Busbars.
(1) General. Busbars shall be sized based on 1000 amperes per square inch for copper and 750 amperes
per square inch for aluminum.
Click to expand...

So for a 4" X 1/4" copper busbar you would have 1 square inch cross section (4*1/4=1), 1 square inch = 1000 amps. Your 3" X 1/4" busbar would have 75% of the 4" ampacity which is 750 amps.
 
nickelec said:
It was a test question making me crazy

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Need the context - write the test question out for us. What test by whom and where, etc..

'v' if on a charger display could mean the charger is in constant voltage charge state vs. constant current. What type battery being charged?
Could just be an obsolete test question ?
 
Well, there IS a convention in which the difference between an Upper case "V" and a Lower Case "v" mean different values, but it generally applies to signals. You can read a halfway decent description on this Wiki page:
https://en.wikipedia.org/wiki/Small-signal_model

How that would apply to a battery charger? No idea... MAYBE what it is telling you is that the transistor gates in the charger are no longer being biased, so that would mean it is done? Or would it mean the gates ARE being biased, so it is NOT done?
 
The only thing I can come up with is a v for the instantaneous voltage at t(time).

How this could or would apply to battery or it’s charger is kinda sketchy in regards to question as it is written.

Mainly used for AC.
 
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