Wolfee,
An F40PH provides both propulsion power and head end power (HEP) for
train lighting, heating and air conditioning. The train power is 440
volt AC and to provide it at the proper frequency for the various
motors and other equipment in the cars, a constant diesel engine rpm
must be maintained. If it is not, the frequency will fluctuate causing
damage to this equipment. Maintaining a constant engine rpm is totally
independent of main generator traction load. Thus, when the engineer
moves the throttle, only the main generator (or technically alternator)
excitation is being changed. The excitation of the main generator
determines the amount of traction power output and thus, the movement
of the locomotive. Therefore, when the HEP is operating, the engine is
at full rpm even though the locomotive may be at a standstill. Amtrak
GE P42s do the same thing.
When the HEP is off line, normal engine speed variation occurs with
throttle position change. The sound made by HEP equipped locomotives,
particularly in closed stations such as Union Station in Chicago, has
been one of the primary objections to such locomotives. The new METRA
Boise locomotives have separate HEP systems driven by smaller quieter
diesels (Caterpiller, I believe). Engine crews also don't like the
constant high engine rpm sound in the cab. Frequently, on multiple unit
consists such as Amtrak trains have, the crew will set up a trailing
unit to provide train HEP power, thus quieting the cab. None of the HEP
systems that I know of can be m.u.ed with each other like traction
power of the locomotive can be. Thus train length is somewhat limited
by the HEP available from one unit.
Bill Barber
On Friday, November 7, 2003, at 09:29 AM, BRHSlist@yahoogroups.com
wrote:
> Date: Fri, 07 Nov 2003 15:22:49 -0000
> From: "wollffee" <wolfee@onebox.com>
> Subject: How does an F40PH work?
>
> I found the operators manual for this loco and it states that the
> engine runs at 893 RPM at ALL times during normal ops. Yet, it still
> has the normal 8 power setting positions. If the motor always runs
> at full speed, how is power to the wheels adjusted?
------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark
Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada.
http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/8ZCslB/TM
---------------------------------------------------------------------~->
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|