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GN Electric Operations continued
General Electric locomotive compressors normally operate
at 150 volts A. C. from the transformer. Power for the
compressors is delivered from transformer to compressor
selector switch in A. C. position, then through compressor
power switches Nos. 44 and 47 to the compressor fuses
and into compressor motors, completing its circuit back
to transformer through the 1000 ampere fuse on back of
transformer above the compressors.
The control circuit for compressor switches Nos. 44 and
47 is 65 volt battery D. C. from compressor snap switch
through snap switch fuse to operating coils of switches
Nos. 44 and 47, completing its circuit back to battery through
compressor governor contacts which lift to stop pumps at
proper main reservoir pressure.
To normally pump up a General Electric cab, close battery
switch, close compressor snap switch, raise pantographs,
as covered by pantograph instructions. Compressors
immediately start to work. Note lap brake valve and
have all reservoir drains and angle cocks closed on hose
not coupled. Start M-G set when pumps stop, at 130 lbs.,
M. R. pressure.
Compressor Selector Switches and Emergency Power for
Pumps When Coming Down Hill With Dead Trolley Line
The compressor selector switches on General Electric
locomotives are operated as follows: SAFETY FIRST.
Plenty fireworks if you do this wrong. The selector switches
have three positions and before moving a selector switch
(1) pull battery switch. (2) Then take reverse lever off
main controller and place it on selector switch to be thrown.
The positions are: normally A. C. switch handle full over
to right facing selector, for transformer power. D. C. handle
straight up and down, or middle position, is for battery
power, and is only used in emergency to pump up train and
release brakes. Regeneration, or handle full over to left,
is running position when trolley is dead. In regeneration
position No. 2 traction motor supplies power to run
compressors while train is in motion only. The regular
compressor governor cuts pumps out at proper pressure. The
speed of compressors are governed by relays X-1 and
X-2 while in regeneration position irrespective of locomotive
speed. Fuse X down in lower left hand corner of No.
1 switch compartment protects relays X-1 and X-2 in case
of trouble. This fuse "X" if defective, will cause pumps
to run at excessive speed.
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(A) In case of failure of trolley power and train can
come down hill (1) pull battery switch. (2) Throw selectors
to full left position or regeneration if train brakes are
released. (3) Close battery switch and watch air gauge to
be sure pumps are running while train is in motion and
keeping up main reservoir pressure.
(B) In case trolley power fails and you have stopped
train so that brakes cannot be released by air remaining
in main reservoirs, then (1) pull battery switch. (2) Throw
one selector to middle or D. C. position. Re-close battery
switch and main reservoir will slowly pump up from batteries.
When it is up to pressure, pull battery switch again
and change both selectors to regeneration or full left
position for running. Release brakes and proceed.
Note: Under these conditions retainers will be handled
as per special instructions as carried in the time card
covering steam operation.
General Electric Locomotives — Compressor Troubles
Compressor trouble shows up as (A) compressors will
not start, or (B) they will not stop.
Compressor starting trouble is rare, and if it does occur,
the following procedure will locate cause.
The compressor control circuit is compressor snap/switch,
snap switch fuse and governor contacts. When snap switch
is on, its fuse okay and governor contacts making, the
compressor switches Nos. 44 and 47 will close on battery
current.
The compressor power circuit is from the selector drum
switch to the individual compressor fuses in No. 2 switch
chamber, and from these fuses to the compressor motors
and then completing power circuit through the 1000
ampere fuse mounted up above pumps on back of transformer.
The selector drum switch may be energized from (1)
the main transformer normally, or (2) from the battery
alone, (3) from the regeneration current of one traction
motor No. 2, depending on position of selector as covered
by its own instructions. Normally, the selectors are set on
A. C. Hence, if trolley is energized, pantograph contacting
it, transformer fans running, then provided switches Nos.
44 and 47 are closed, pumps will run unless their fuses are
blown, or switch contacts badly oxidized. SAFETY ALWAYS.
Lower pantographs and close ground switches to
investigate trouble.
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Pumps Fail to Stop
Runaway compressors seldom occur on single unit engines,
except when a compressor switch might weld closed,
or the governor stuck closed. The quick tests to locate
which is the trouble are:
(a) Turn off compressor snap switch. This will stop
both pumps regardless of governor unless a switch is welded
in, then that pump will keep running.
(b) Raise governor box and pull up on governor rod.
This should stop both pumps. If a pump keeps running
when either the snap switch is off, or the governor raised
to its off position, then a pump switch No. 44 or 47 is
welded in, on a single cab. Lower pantographs, close
ground switch and after removing arc box on both
compressor switches, pry the welded one apart and clean up
the both contacts, replace arc boxes and get going.
This particular above data applies to single unit operation,
as runaway pumps are quite common troubles on multiple
operation of two and three units due to the same
causes as above, but in addition to this, runaway pumps are
caused by many other causes on multiple cabs as will be
covered later.
Runaway pumps on multiple cabs are common occurrence,
as a result of the following causes:
(1) Air hose between cabs not properly coupled and
cut in. See instructions on coupling air hose between cabs.
(2) When any one of a multiple cab combination is shut
down and battery switch opened without also turning off
compressor snap switch on that cab.
(3) Differences in main reservoir pressure when, for
example, a dead cab is coupled to a live cab. The pumps
on live cab will continue to run until the main reservoir on
dead cab is pumped up to the necessary pressure to raise
or open the governor of dead cab. The control jumpers
between cabs keep live cab pumps running until all governors
lift in all cabs coupled by air hose and control jumpers.
When main reservoir pressures equalize, this condition
disappears. To prevent damaging air gauges and overloading
the pump motors, fireman can turn off snap switches on
pumps in cabs that are overcharging and if necessary
open main reservoir drains until equalization takes place.
(4) Defective governor setting in any one cab (too high
setting) will cause all cabs to overcharge main reservoirs.
To get in off road with minimum trouble, for example,
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any one of three cab governors stick in or will not lift, take
a piece of card board, stick, or heavy paper and place it
in governor so its contacts cannot make. The other governors
will handle the pumps. Be sure to report same on
arrival. If, while charging up a train line, the pop valves
start letting go, to simplify matter (a) try turning off
snap switches in the middle and trailing cabs, let head cab
pump up train line and after main reservoirs are equalized,
then cut in your pumps on all cabs. (b) If cutting out snap
switches does not stop runaway pumps, block out governors
in trailing cabs until equalization of main reservoirs
occurs. Do not let air gauges be damaged by over pumping.
Electric Locomotive Blowers or Cooling Fans
Power apparatus on all Great Northern electric locomotives
is air cooled. The M-G sets have their own built in
turbine fan, while transformers and traction motors are
cooled by individual motor driven fans or blowers.
The General Electric Blowers - Transformer Blowers
General Electric transformers are normally cooled by
two five horsepower motor driven fans, which are operated
by single phase power from main transformer, 750 volts,
and they run continuous all the while pantograph is up
against a hot wire. There are no switches connecting them
to transformer. They are direct connected by their own
individual fuses, and the auxiliary power fuse. DANGER:
This is 750 volt A. C. and must not be worked on only
when pantograph down and ground switches closed. If one
transformer fan should fail, removal of fuse will cut it out,
and trip may be completed on one transformer fan. In
winter time one fan is usually cut out and its air intake
blocked. Otherwise both should operate.
General Electric Traction Motor Blower
The General Electric traction motors are cooled by a
motor driven double fan located down under M-G coupling.
This traction blower motor is a 50 H. P., 3 phase, 750
volt machine. It is supplied power by the taps on
synchronous motor, to which it is connected by three fuses and
three remote controlled magnetic switches Nos. 42, 43 and
46.
Note: Engine cannot be operated over fifteen minutes
full load without blower.
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