Index Locomotives - books DIESEL LOCOMOTIVE OPERATING NO. 2315 for MODELS F9, FP9, FL9 - manual 1997 year
|
|
|
ELECTRICAL
F9-5-657
the safe RPM of the traction motor
armature; thus a high speed gear ratio is
required for high speed train operation. A
low speed gear ratio is needed to start and
use full horsepower with low speed
tonnage trains without overheating and
damaging the electrical equipment.
503
Reverser
Movement of the reverse
lever to the forward or reverse position
energizes the respective FOR or REV
magnet valves on the reverser, Fig. 5-3,
located in the electrical cabinet. When
either of the magnet valves is energized it
allows control air to pass through the
valve, moving the reverser to the desired
direction
(with
four
long
segments
showing on reverser drum, the reverser is
in forward; eight short segments can be
seen when in reverse position).
504
Transition
This term is ap-
plied to the changing of traction motor
electrical
connections
on
all
Diesel-
electric locomotives so that full power may be obtained from the main
generator within the range of its current and voltage limits. To look at it
another way, transition is a method of adjusting the traction motor
"back pressure" (counter -e.m.f.) bucking the input of power from the
main generator so that this back pressure will not become too high at
higher speeds nor too low at lower speeds.
- 53 -
F9-5-657
ELECTRICAL
Standing still the traction motors have practically no "back
pressure," or resistance to the input of current from the main generator.
However, as the locomotive speed increases after starting in series-
parallel (transition 1), Fig. 5-4A, the "back pressure" of the traction
motors builds up and causes the main generator "pressure" (voltage) to
increase so that it can continue forcing current into the motors. Al-
though the main generator can vary its voltage over a wide range, there
is a practical operating limit to its ability to increase its voltage. If this
practical voltage limit were exceeded, the power output of the main
generator and correspondingly, the engine, would drop off. To prevent
this loss of power, a change is made in the electrical circuit just before
the drop-off begins.
The first change, Fig. 5-4B, from transition 1 to
2 (series-parallel-shunt) connects a by-pass (shunt) circuit around each
of the traction motor fields.
Shunting the traction motor fields effects
a reduction in the "back pressure" of the traction motors, which in turn
allows the voltage in the main generator to reduce itself (with a con-
stant KW generator, as the voltage goes down the amperage goes up,
and vice versa). Thus, by shifting to transition more current can pass
Series-Parallel
Series-Parallel Shunt
Fig. 5-4A
Fig. 5-4B
- 504 -
ELECTRICAL
F9-5-657
through the traction motor armatures to maintain the full power output
of the locomotive.
As the locomotive speed increases there is again a tendency for
the power to drop off. This time, when the main generator reaches suf-
ficient voltage, a complete change in the electrical circuit is necessary
to once again reduce the "back pressure" of the traction motors. When
this change, from transition 2 to 3 (parallel), Fig. 5-5A, is completed
the main generator continues the full application of power until a still
higher locomotive speed is reached. At this time, when the voltage in-
creases, the motor shunting contactors are again closed (reducing the
traction motor "back pressure") effecting transition from 3 to 4 (paral-
lel-shunt), Fig. 5-5B. With decreasing speeds, as caused by grades, a
reverse sequence of transition takes place to prevent exceeding the cur-
rent limitations of the main generator.
Parallel
Parallel Shunt
Fig. 5-5A
Fig. 5-5B
- 505 -
F9-5-657
ELECTRICAL
505
Transition Control Circuit
Two relays (FSR and PTR), Fig.
5-6, actuate the changing of traction motor connections in the forward
and backward transition.
E-I type transition is an automatic transition which, as the name
implies depends primarily upon generator voltage and current (voltage
and current ratio) for operation. Forward and backward transition are
initiated by two (2) through cable type relays (FSR and PTR) which
operate on generator voltage and are biased by generator current. This
transition differs from the earlier transition which was dependent pri-
marily on generator voltage to initiate all forward transition steps and
backward transition from shunting positions. Generator amperage was
used for initiating backward transition from parallel.
Transition Relays Fig. 5-6
- 506 -
ELECTRICAL
F9-5-657
Transition is used to initiate a change in motor connections so
that full power may be obtained from the generator within its current
and voltage limits. In addition to satisfying the above condition, E -I
transition permits transition to take place at intermediate throttle posi-
tions assuming that the locomotive is traveling at or above transition
speed.
Transition can take place on these locomotives equipped with
E-I type transition, assuming locomotive is at transition speed at throt-
tle position 2 and above, resulting in a fairly constant KW output
throughout the speed range of the locomotive for any given throttle po-
sition. At low generator current, the FSR and PTR relays pick up at a
relatively low generator voltage and as the generator current is in-
creased, the relays pick up at a higher generator voltage, Fig. 5-7.
In
Transition Relay Settings
Fig. 5-7
- 507 -
F9-5-657
ELECTRICAL
other words, the FSR and PTR
relays operate at a fixed current
voltage
ratio
at
the
various
throttle positions and KW levels.
506
Load
Regulator
The load regulator, Fig.
5-8, is an automatically operated
rheostat connected in series with
the battery field of the main
generator. Engine oil pressure is
used to force the vane motor of
the rheostat brush arm to vary its
position.
Oil
pressure
is
impressed on either side of the
vane, as directed by a load
regulator pilot valve located in the engine governor.
The load regulator has two components: (1) the pilot valve in
the engine governor, and (2) a self-contained unit consisting of a hy-
draulic vane type motor attached to the commutator type rheostat
.
The
only external wiring connections are two leads to the generator battery
field circuit.
For the purpose of load regulation, the engine horsepower out-
put is determined by the rate of fuel consumption. Thus, for each posi-
tion of the throttle there is a definite rate of fuel consumption when the
engine is loaded. The rate of fuel consumption is related to the position
of the governor power piston, which controls the opening of the injec-
tor racks. If the load on the engine should be such that more fuel is de-
manded (to rotate the engine at the RPM "ordered" by the throttle) than
the predetermined balance point (between load and fuel consumption),
the load regulator pilot valve will cause the load regulator to reduce the
engine load the required amount by reducing the battery field strength.
- 508 -
ELECTRICAL
F9-5-657
If the engine requires less fuel than the predetermined setting,
the load regulator increases the load on the engine by increasing the
battery field excitation of the main generator. In this manner, battery
voltage, temperature changes in the generator windings, or locomotive
speeds do not cause overloading or underloading of the engine and a
constant power output is maintained for each throttle setting.
An overriding solenoid, ORS, in the governor, is energized
whenever the battery field contactor is open; such as whenever the
throttle is in idle, during transition from 3 to 2 or 2 to 3, or during
wheel slip action. The energizing of this solenoid causes the load regu-
lator to move into or toward the minimum field position, depending
upon the length of time that the ORS is energized, unloading the en-
gine. Another switch that can energize the ORS is the overload micro-
switch (OLS) located in the governor. The OLS is actuated whenever
the engine is overloaded; energizing the ORS to bring the load regula-
tor toward minimum field position, reducing the load on the engine.
507
Engine Speed Control
The throttle lever, in the controller, has
ten positions: STOP, IDLE and RUNNING SPEEDS 1 THROUGH 8.
Each throttle step, from 2 through 8, increases the engine speed 80
RPM. The throttle lever operates a phenolic cam which controls en-
closed roller switches to distribute current from a "hot wire" to one or
more other wires, depending on the position of the throttle.
The governor is designed so that the energizing of various com-
binations of four governor solenoids (AV, BV, CV, and DV) causes the
engine to respond to the "orders" of the throttle. The "ENGINE SPEED
CHART" shows the various combinations of solenoids that are ener-
gized to obtain the desired engine speeds for the various throttle posi-
tions. The Engine Speed Control schematic diagram, Fig. 5-9, shows
the method of energizing the various governor solenoids for the various
positions of the throttle.
- 509 -
F9-5-657
ELECTRICAL
ENGINE SPEED CHART
Throttle
Governor Solenoids Energized
Engine Speed
Position
A
B
C
D
RPM
STOP
*
0
IDLE
275
1
275
2
*
355
3
*
435
4
*
*
515
5
*
*
*
595
6
*
*
*
*
675
7
*
*
755
8
*
*
*
835
Effect of
Solenoids on
Engine RPM
+80
+320
+160
-160 (or stop)
Engine Speed Control
Fig. 5-9
-510-
|
|
|