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GN Electric Operations continued
transformer driving synchronous motor, in which case SR1 relay
would have to be blocked closed after machine reached
full battery speed, 250 R. P. M.
(g) Closing relay SR2, closes switch SM1, which
interlock closes AR time delay relay, AR closes switch RL,
and SM3. RL interlock opens SL, and switch L closes.
M-G set is running normal when switches ML, RL, L,
El, .E2, SM1, SM3 all closed.
Events: (1) Set starts by battery driving generator to
250 R. P. M. (2) Relay SR1 connects synchronous motor
to transformer as an induction motor. (3) At 600 R. P. M.,
relay SR2 applies field to synchronous motor and
synchronizes M-G set with line.
Motoring Switches
(h) Notching out on speed lever closes D. C. line switch
L1, G1, G2. Further notching of speed lever operates "G"
contactors which cut out generator field resistance up to
full voltage.
High Speed Motoring and Regeneration
(i) Notching out on field lever closes switch L2, RG1,
RG2, then pressing in separate field control button closes
stabilizing switches L31, L32, L33, L34.
Note: In service, balancing voltmeter must be at zero
when this is done or you will flashover motors and break
drawbars.
Further notching of field lever operates other RG
regenerative exciter field contactors. If field is weakened,
motors will increase speed. If field is increased, speed will
drop. The spot diagrams will give contactor and switch
sequences for all notches.
Blower Switch Sequence
(j) (1) Moving blower control switch to start, closes
switches A1, A2, A3. (2) Moving it to RUN position,
switches A1, A2, A3 stay closed until master controller is
notched, then A3 opens and blowers all run on A1 and A2
closed.
SAFETY ALWAYS. Do not touch anything.
Motor Generator Set
Set engine brake, and with M-G set running, it is okay
provided following switches are found closed: ML, RL, L,
E1, E2. SM1, SM3.
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Straight Motoring
Take one notch on speed controller. Switches L1, G1, G2
must close or engine will not move, regardless of any other
switches in.
Regeneration Test
(1) Shut off all control levers. (2) Pull field lever out.
Any notch okay. (3) Hold in the separate control button
and take one notch only on speed lever, then let separate
button go. Engine will regenerate if following switches are
closed: L2, L31, L32, L33, L34, G1, G2, RG1, RG2. These
must be in.
Note: Ammeters indicate this data when you make
terminal test before leaving shop. The sequence merely tells
you what happens as you make the moves.
General Data on Trouble Shooting And Quick Tests For
Locating And Clearing Locomotive Trouble
(A) SAFETY ALWAYS. Only live men can take care
of their jobs and their families. Nobody must take chances
anytime around high voltage, as the first chance is usually
the last.
General Data
(B) Trouble shooting ability mainly consists in
knowing how your engine should work normally; otherwise you
will blow up something, if a hit and miss system is used.
Know the sequence and be careful.
Motor Generator Set Sequence
(C) Great Northern motor generator locomotives all
have the same characteristics.
(1) M-G set must start from rest.
(2) Synchronous motor must be connected to the
transformer at a definite speed.
(3) The synchronous motor must be synchronized with
the line at near full speed.
If all three events do not properly occur in their orderly
sequence, you have trouble and locomotive will not move.
(D) Hence, trouble can show up as follows:
(1) M-G fails to start from standstill.
(2) M-G starts okay, but fails to take next step of
connecting to transformer.
(3) M-G starts okay., connects to transformer okay, but
fails to synchronize with line.
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There are only three events concerned in getting an M-G
set from standstill to full speed and synchronized on line.
The circuits, relays, fuses and devices controlling each event
should be known and understood. Assuming that the M-G
set starts, changes over to transformer, synchronizes and
is running okay, then if locomotive fails to move, trouble
will be found on the traction circuits consisting of main
generators, and their field circuits, traction motors, and line
switches, circuit breakers, overload relays and the various
control circuits which operate all the others.
Traction Circuits
(E) The D. C. traction circuit consists of the main
generators and the traction motors. These apparatus are
connected together by means of power cables, circuit
breakers and electro pneumatic power switches. The generator
power output is governed by the field current supplied to
it through a system of field contactors controlling the
external resistance units.
The master controller operates all switches and
contactors governing the movement, speed and performance
of an electric locomotive. Hence, if an electric locomotive
fails to move while its M-G set is running normally, there
can only be one or both of two things wrong:
(1) No connection between generator and motors.
(2) No field on generator.
In other words, some necessary switch is not closed, or
it is closed on oxidized contacts, or a field fuse is blown
on generator field circuit, or master controller is dead.
The Great Northern Railway motor generator locomotives,
while basically alike, have different control systems.
This necessitates covering each kind of locomotive separately
for trouble shooting data, as will be done.
General Electric Trouble Shooting
Pantograph will not raise: be sure all pantograph-lowering
buttons are pulled out, and all trolley relays properly
closed and ground switches out.
Pantograph raises, but slowly pulls away from wire as
compressors pump up main reservoirs, caused by; a
pantograph-lowering button being in, or a trolley relay tripped
out.
Pantograph against wire: transformer fans do not run:
Either (a) no power on trolley line, (b) blown fuses on
fans, (c) roof fuses blown.
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If pantograph sparks when pulled away from line, the
line is hot.
Compressors: If both fail to run, either a blown fuse, or
turned selector switch on dead one. Line is hot if transformer
fans run.
Motor Generator Set Will Not Start
To start M-G set, switches 1 and 2 must close, and stay
closed until set is up to full speed.
(a) Check ground relay, trolley relay, and overspeed
relay, and be sure they are closed.
(b) Be sure control air is 70 lbs., and that battery
fuses are okay. If cab lights burn, battery is okay.;
also auxiliary control fuse okay When both headlights
burn, auxiliary fuses okay.
Note: General Electric M-G sets fail to start in two
ways:
(1) They will not move at all, (2) they only move while
you hold start button in, and quit when you let button go.
The M-G stop button must be pulled full out.
(c) Push and hold in M-G start button. Check TDR2.
If it is closed, your ground, trolley and overspeed relays
are okay. If TDR2 is open, some one of the three above
relays are open, or they may be closed and have a broken
pigtail shunt. If TDR2 is closed and switches 1 and 2 are
open, then your trouble is a dirty interlock on No. 4 out
or No. 36 out switches, or one of these switches might be
welded in, which would break the interlock circuit. If M-G
set starts, but stops as soon as you let go of M-G start
button, trouble is found thus:
(d) One man watch switch No. 40, while other man
pushes in and holds M-G start button. If No. 40 closes
while button is held in, the trouble is a dirty or bad
contact on No. 40 in interlock.
(e) If No. 40 does not close at all when M-G start
button is pushed in, trouble is usually a dirty MGR relay
contact, but it could be on any one of the three red M-G stop
button contacts. The point is, unless switches 1 and 2 close,
M-G cannot start, and unless No. 40 closes, and stays
closed, none of the M-G switches will stay in.
M-G Set Starts, But Will Not Connect To Transformer
(f) Fails to take first bump, in other words, switches 3,
5, 9 fail to close. Check relay PR3. If it is not closed
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