close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2406426

код для вставки
Aug. 27, 1946.
G, E, KlNG
'
I 2,406,426
CONTROL SYSTEM
Filed 001;. 1.7. 1944
bu
RU“
8.
»
WITNESSES:
Z24
8%.
'
I
'
' INVENTOR
.
’ GeofyeE/(fng
M2. BY
ATTbRNEY
Patented Aug. 27, 1946
2,406,426
UNITED STATES-PATENT OFFICE
2.40am;
CONTROL SYSTEM
George E. King, Swissvale, Pa., assignor to West
inghouse Electric Corporation, East Pittsburgh,
Pa., a corporation of Pennsylvania
1
Application October 1'7, 1944, Serial No. 559,067
6 Claims. (Cl. 172.—179)
2
The present invention relates to variable
voltage control systems, and more particularly to
7 to provide a variable voltage drive in which ace
curate adjustment of the maximum braking cur
rents between certain limits is obtained.
A further speci?c object of this invention is to
a variable voltage drive for operating or auto
matically controlling the operation of motors con
nected to various types of mechanical loads. In
certain of its aspects, this invention is related
to a copending application of George E. King and
William H. Formhals, Serial No. 559,068, ?led on
the same date as this application and entitled
Control system (W. E. Case 23,453), to a copend
'. provide a variable voltage drive including means
for independently adjusting both the accelerat
ing and the braking current.
Other objects and advantages will become more
apparent upon a study of the following disclosure
when considered in conjunction with the accom
ing application of George E. King, Serial No.
panying drawing, in which:
The single ?gure thereof illustrates a variable
and entitled Control systems (W. E. Case 23,417),
voltage drive for a motor embodying the prin
and to another copending application of George
ciples of this invention.
E. King, Serial No. 559,065, also ?led on the same 15
Referring now to the drawing, the variable
date as this application and entitled Control sys
voltage drive comprises a main motor M which is
tems (W. E. Case 23,232).
provided with a separately excited ?eld winding
This invention provides certain improvements
MSF and a regulating ?eld winding MRF. The
in variable voltage control systems in which rotat
motor separately excited ?eld winding MSF pro
ing regulators are employed to regulate certain 20 vides the main excitation for the motor while the
electrical quantities of the system, and the inven
motor regulating ?eld winding MRF provides the
tion as hereinafter described and as illustrated
necessary corrective excitation for the motor
in the drawing is speci?cally directed to a control
under certain operating conditions to maintain
for a direct-current motor embodying provisions
the motor armature currents within permissible
for limiting the motor armature current whether £25 limits.
559,066, ?led on the same date as this application
the motor is operating normally as a motor or
A main generator G is utilized to energize the
motor M. Its armature winding is connected in
series with the motor armature winding. The
as a generator.
main generator G is provided with a separately
In the copending applications hereinbefore re 30 excited ?eld winding GSF which provides the
ferred to, automatic speed regulation of the motor
main excitation for the generator. It also has a
is provided in conjunction with current limiting
regulating ?eld winding GRF which under cer
during regenerative periods when the motor is be
ing overhauled by its mechanical load and driven
protection. In this application, however, auto
matic speed regulation of the motor is not shown
in the interest of simplicity. It will be apparent,
however, to one skilled in the art that automatic
speed regulation in the variable voltage drive
hereinafter disclosed may be obtained in a man
ner similar to that disclosed in the said copend
ing applications. It will also be apparent to one
skilled in the art that this invention is not neces
sarily limited to motor control, since automatic
tain operating conditions of the system provides
35
the corrective excitation for the generator neces
sary to maintain the motor armature currents
within permissible values. The ?eld system of
this generator also includes a commutating ?eld
winding GCF and a di?erential ?eld GDF which
is utilized near the end of the braking periods
when the generator voltage has decreased to a
certain minimum value to neutralize the residual
voltage of the generator.
A control generator C is utilized to provide the
regulation of the maximum permissible currents
supplied to an electrical load of substantially any
corrective currents necessary to maintain the
type susceptible of regulation may be had.
45 motor armature currents within permissible
A principal object of this invention is to pro
values. This control generator is provided with
vide a variable voltage drive for a motor in which
calibrating ?eld windings, designated CF! and
the motor armature currents are automatically
CFZ. These windings are differentially arranged,
limited within permissible or desired values.
that is, they produce opposite ?uxes and are sepa
Another and more speci?c object of this inven
rately employed to provide the desired excitation
tion is to provide a variable voltage drive in
for the control generator C during accelerating
which accurate adjustment of the maximum ac
and braking periods of the motor either in the
celerating current between certain limits is ob
forward or reverse directions of operation thereof.
tained.
A regulating ?eld winding for the control gen
Yet another speci?c object of this invention is 55 erator designated CRF is excited by the drop
2,406,426
3
across the main generator commutating ?eld
GCF. Thus the excitation of the regulating ?eld
CRF depends upon the current circulating in the
motor generator armature circuit.
The control generator C is of the self-energiz
ing type and is provided for this purpose with
a shunt connected armature current energized
?eld winding C‘SF which is connected in series
4
erator. In its deenergized position circuits are
established for energizing the calibrating ?eld
winding CF2. In its energized position, the
calibrating ?eld winding CFI may be energized.
The series coil C5 of this relay is connected in
series in the motor generator armature circuit.
The shunt coil C6 is connected across a suitable
source of potential which may, for example, be
an exciter driven at a constant speed along with
of the control generator. This resistor is so ad 10 the main generator and the control generator C
but which is not shown in the interest of sim
justed or selected in its electrical resistance value
plicity. The ampere turns of the coil C5 and
that the resistance line of this shunt ?eld cir
C6 add when the motor is accelerating and sub»
cuitpis tangent to the initial straight line por
tract during braking periods of the motor when
tion of the no~1oad saturation curve of the com
trol generator. It then becomes the function of 15 the motor is operating in the forward direction.
with a resistor SR across the armature terminals
They subtract during acceleration and add dur
either of the calibrating ?eld windings depend
ing braking when the motor is operated in a
ing upon which is energized, operating in con
reverse direction. This relay may be adjusted to
junction with the regulating ?eld winding to
pick up with 10% of full-load current in the
select the proper operating point of this gen
erator along the tangent curves. With this ar 20 series coil C5 aiding the shunt coil and to drop
out with 10% of full-load current in the series
rangement and depending upon the net excita
coil subtracting from the shunt coil.
tion of the control generator, this generator may
The VR or voltage relay is used to select the
have an electrical output or rather a voltage out
generator or motor regulating ?eld and to main
put equal to the ordinate of any of the points
of tangency of the curve of the resistance line 25 tain full generator voltage when braking due to
strengthening of the motor shunt ?eld, the VR
and the initial straight line portion of the no
relay has its single or shunt coil connected across
load saturation curves. The circuit is so ar
the generator armature in series with the con
ranged, that is, the ?eld windings of the ma
tact TRI of the timing relay TR. It is adjusted
chine are so arranged when connected, that the
ampere turns from the regulating ?eld winding 30 to pick up near maximum generator voltage. It
drops out due to the TR relay contact TRI open
are always opposed to the ampere turns from the
ing and deenergizing its coil.
connected calibrating ?eld winding.
The TR or timing relay controls the operation
Suitable magnetic controllers are provided in
of the voltage relay VR. It is an inductive time
the system which respond to motor armature
currents to connect the control generator in the 35 element relay with an inherent short time ele~
ment when both coils are deenergized. The main
system such that the control generator does not
or pickup coil C2 is connected in series with the
effect the operation of the generator or motor
LVB contact and the rheostat interlock RI across
until the ampere turns of the regulating ?eld
a suitable source of energizing potential. The
winding CRF are greater than the ampere turns
of the connected calibrating ?eld winding. The 40 rheostat interlock closes when an the generator
?eld portion of the resistor GR has been shorted
ampere turns of the calibrating ?eld windings
and remains closed during the motor ?eld weak
can be preset by proper adjustment of the taps
ening portion of the rheostat. This motor ?eld
provided on the adjustable calibrating resistors
weakening is accomplished over the motor rheo
ARI and ARE, respectively, connected in series
with the calibrating ?eld windings CFI and 45 stat section MR. The holding coil Cl is con~
nected in series with the motor regulating field
CFZ. With this arrangement it is possible to ob
so that it will hold the TR relay closed as long
tain independent values of accelerating and
as it it is energized by the control generator dur
braking current.
ing the braking cycle.
The CR or current relay is used to connect the
The FW or motor separately excited ?eld weak
control generator armature to the generator and 60
ening relay is used to insert the motor rheostat
motor regulating ?elds at the proper time. If
resistor MR and its conducting segment MRI in
it is desired to limit the accelerating current, for
series with the motor shunt ?eld. Its shunt coil
example, to 150% of full-load current, then the
Cl is connected across the generator armature
CR relay should pick up near this value. The
CR relay has a series coil C4 connected in series 5.5 in series with the LV‘! contact. The other is
connected across the positive and negative ter
relation with the motor and generator armatures
minals indicated which again may be eXciter
and a shunt coil C3 excited according to the elec
buses, in series with either the F! and
con
trical output of the control generator. The
tacts or the RI and R2 contacts depending upon
ampere turns of these coils are in opposition when
the control generator voltage output is due to the 60 which of the F and R relays are energized and
the generator rheostat GR or the contacts VRI
ampere turns of either of the calibrating ?eld
if the VR relay is energized. This relay FW is
windings CF! or CR2 being greater than those
adjusted to pick up at a different generator volt
of the regulating ?eld winding and the ampere
age which may, for example, be somewhat less
turns of the two coils of the CR relay are cumu
lative when the voltage output of the control 65 than that required to pick up the VR relay.
Energization of both coils is required for pickup.
generator C is due to the ampere turns of the
The FW relay drops out when the coil C3 thereof
regulating ?eld Winding being greater than those
is deenergized or the generator voltage decreases
of either of the calibrating ?eld windings. Un
su?lciently.
der this last mentioned condition, the CR relay
The LV or low voltage relay is used to energize
picks up and establishes certain circuits for en 70
the generator shunt ?eld GSF in conjunction
ergizing the generator regulating ?eld or the
with either of the forward or reversing contactors
motor regulating ?eld or under certain operating
F and R depending upon whether the forward or
conditions both of these ?elds.
'
reversing push button Fwd or Rec is depressed.
The RC or reverse current relay is used to select
, This relay in a sense e?ects the operation of the
the correct calibrating ?eld ‘of the control gen
2,406,426
5
timing relay TR and the ?eld weakening relay
FW. Energization of this relay is initiated by
depressing either the forward or reverse push
6
potential adjacent the contacts RI through the
contact members Fl, the field winding GSF, the
contact members F2 through the generator rheo
button.
stat GR to a point of negative potential. Thus
The motor and generator ?eld rheostats, desig Or a voltage is generated by the generator, and this
nated respectively, MR and GR, together with the
voltage is applied across the motor armature
rheostat interlock RI are controlled from a single
terminals. Since the motor ?eld winding MSF
handle or handwheel H. The arrangement of
is connected from its point of positive potential
the motor and generator rheostats is such that
through the back contacts FWZ of the ?eld weak
it is ?rst necessary to strengthen the generator 10 ening relay to a point of negative potential, this
separately excited ?eld GSF before weakening
?eld winding is excited at its maximum voltage.
the motor separately excited ?eld and vice versa.
The motor thus accelerates under the in?uence
When the generator rheostat GR, is completely
of a fully excited ?eld winding. The contact
shorted, the contact arm CA for the rheostat
members Fl and F2 also complete an energizing
interlock engages the arcuate conducting segment 15 circuit for the coil C8 of the ?eld weakening
and thus completes an energizing circuit for the
relay .FW. As shown, this ?eld is connected in
coil C2 of the timing relay TR.
parallel with the generator ?eld GSF. Hence,
The forward and reversing contactors respec~
its energization will be understood without fur
tively designated F and R are required to reverse
ther tracing of the circuit through the Fl and
the main generator separately excited ?eld GSF 20 F2 contacts. The contact members F3 open while
and the motor regulating ?eld MRF. It is neces
the contact members F4 close. Closure of the
sary to reverse the generator ?eld GSF in order
contact members F4 inserts a large portion of
to reverse the direction of rotation of the motor
the adjustable calibrating rheostat ARI in series
armature. The current through the motor ar
with the control generator calibrating ?eld CFl.
mature reverses and consequently is in the re 25 This ?eld winding is arranged to produce a mag
verse direction through the control generator
netic ?eld linking the rotor of the control gen
regulating ?eld C-RF. The polarity of the con
erator which is in opposition to that produced
trol generator armature is, therefore, reversed,
by the regulating ?eld CRF for forward opera
and it is necessary to reverse the motor regulat
tion of the motor. Since the excitation of the
ing ?eld to keep its polarity correct with respect 30 calibrating ?eld CF! upon closure of the contact
to the motor shunt ?eld. Analogous considera
members F4 is lower than that obtained when
tions apply to the coil 08 of the FW relay.
the contact members F3 are closed by reason of
Starting of the system for operation of the
the setting of the rheostat taps, the currents in
motor in the forward direction is accomplished
the motor armature circuit are limited at a lower
by pressing the forward push button Fwd. This 35 value during acceleration of the motor. Such
immediately closes the back contacts of the for
a feature, for example, may be desirable if the
ward push button which in conjunction with the
motor is driving a high inertia mechanical load
stop push button now closed completes an ener
through a suitable friction drive. Under such a
gizing circuit for the coil of the low-voltage re
condition, it is desirable to accelerate this high
lay LV. This relays picks up opening its contact 40 inertia mechanical load without causing slipping
members LVI and disconnecting the generator
of the friction drive. Hence, it is desirable to
differential ?eld from its position across the gen
limit the motor armature currents more as a
erator armature terminals. The contact mem
means to prevent excessive accelerating torque
bers LVZ close and complete an energizing cir
of the motor than to limit the motor armature
cuit for the coil C1 of the ?eld weakening relay 45 currents to prevent damage to the electrical cir
FW across the main generator armature. The
cuits. Both the accelerating and braking re
contact members LV3 close and in conjunction
sistors, of course, may be adjusted to permit high
with the stop push bottom complete a holding
armature currents during initial periods of ac
circuit for the coil of the low-voltage relay LV.
celeration and braking if desired. The contact
When the contact members LV4 close, an ener
members F5 and F6 when closed function to par
gizing circuit for the coil of the forward con
tially complete energizing circuits for the motor
tactor F is completed. This circuit includes the
regulating ?eld winding MRF across the control
reversing push button designated Rev, the con
generator. Th'ese contact members determine
tact members LV4, the coil of the forward con
the polarity of the motor regulating ?eld for
tactor F and the back contact members R8 of
forward operation of the motor to provide the
the reversing contactor. The contact members
cumulative relationship of the motor ?elds. The
LV5 also close. These contact members normal
contact members F1 in conjunction with the
ly complete an energizing circuit for the coil of
contact members VRll when closed, establish a
the reversing contactor. This circuit, however,
holding circuit for the coil of the F contactor
at this stage of operation is not completed, since 60 which is independent of the reversing push but~
the forward push button is depressed and its
ton. This eliminates any possibility of reversing
back contact members which are essential to this
the motor at high generator voltages. It is first
energizing circuit are open. Closure of the con
necessary to depress the stop button and deen
tact members LV6 completes a partial energizing
ergize the LV relay thus decelerating the motor
circuit for the coil C2 of the TR relay. This cir 65 under the influence of its ?eld windings. This
cuit, however, ‘is open at the rheostat interlock
provides a decelerating cycle substantially the
RI, since the conducting segment and its con~
reverse of the accelerating cycle. This circuit,
tact arm CA are not in mechanical engagement.
however, is not established until the generator
Energization of the LV relay as previously de
voltage has approached its maximum values since
scribed energizes the coil of the F relay for the
the VR relay does not pick up until such a volt
assumed forward operating condition of the mo
age obtains. Opening of the contact members
tor. This relay picks up and closes its contact
F8 prevents the coil of the reversing contactor ‘
members Fl and F2. This establishes an ener
R from being energized when the forward push
gizing circuit for the generator ?eld winding GSF
button is released and its back contact members
which may be traced from the point of positive
closed.
2,406,426
7
8
Since the motor is now operating at its full
field speed, its speed of rotation is fairly low. If
it is desired to increase the speed of the motor,
contact members VR3 ClOSe and shunt the con
tact members FWI which originally connected the
motor regulating ?eld across the control genera
tor. Thus irrespective of the position of the con
tact members FWI the motor regulating ?eld is
connected across the control generator. Under
the present operating conditions, the motor regu
lating ?eld now functions by itself to limit the
motor armature currents. The contact members
VH4, in conjunction with the contact members
Fl, form a holding circuit for the coil of the F
contactor which is independent of the position
of either of the forward or reversing push but
tons. As the motor approaches the preestab
lished speed the accelerating armature current
decreases and the current relay CR drops out
due to the fact that the excitation of the control
generator is now predominantly due to the cali
brating ?eld CFI. This disconnects the control
generator from the motor regulating ?eld. The
motor armature current decreases to the value
required to drive the load at the selected speed.
Should the operator desire to increase the speed
of the motor and thus turn the rheostat further
in the counterclockwise direction to insert more
of the motor rheostat in series connection with
the motor shunt ?eld winding, the excitation of
the motor separately excited ?eld MSF will be
weakened thereby causing the motor to acceler
ate. If under this accelerating condition the mo
tor armature current increases su?iciently, the
CB relay will again close and the control gener~
ator will act on the motor regulating ?eld MRF
the handle or handwheel H may be rotated in a
counterclockwise direction.
This will shunt in
creasingly larger portions of the generator rheo
stat GR to increase the excitation of the gener
ator ?eld GSF and hence increase the electrical
output of the main generator. Thus, the motor
will tend to increase its speed. Eventually when 10
all of the generator ?eld rheostat is shunted, the
contact arm CA closes the rheostat interlock and
completes an energizing circuit for the pick-up
coil C2 of the timing relay
This timing
relay is thus energized and closes its contact 15
members TRI, thus connecting the coil of the
voltage relay VR across the generator armature
circuit. The voltage relay, however, may not at
this time pickup, since the generator voltage is
more than likely not up to or closely approach
ing its maximum value.
20
As the generator volt
age builds up, it causes increasingly larger cur
rents to ?ow through the motor armature, the
control generator regulating ?eld CRF and series
coils C5 and Ct. respectively, of the RC and CR 25
relays.
As soon as the current builds up, for ex
ample, to 10% of the motor full-load amperes,
the reverse current relay RC picks up and ener
gizes the calibrating ?eld CFI of the control gen
orator. If the adjustable calibrating rheostat
A35 has been set to limit the accelerating cur
rent to say 150% of full-load current, then the
current relay CR will close when the current
approaches 153% of the full-load current since
then the coil C3 then aids the coil C5. The relay
CR upon closing connects the generator regulat
ing ?eld GRF to the control generator armature
through the back contact VRZ and the front con
tact CR1, respectively, of the VR. and CR relays,
so that the ampere turns of the regulating ?eld
GRF are in opposition to the ampere turns of the
shunt ?eld GSF. This action of the control gen
erator on the main generator regulating ?eld
prevents the generator voltage from changing too
rapidly and so limits the accelerating current to
1.50% of the motor full-load current. As the
motor speed approaches the full ?eld speed, the
l'ilW relay picks up and closes its contact members
FW I. This, through the medium of the contact
members F5 and F6, connects the motor regulat
ing ?eld MRF across the control generator to be
energized in the proper direction. When the
back contact members FWZ open, these contact
members which’ normally shunt the motor rheo
to limit the current as hereinbefore described.
Assume the operator desires to decrease the
motor speed and turns the rheostat to a low-speed
setting at reduced generator voltage. The motor
?eld is strengthened causing the motor to regen
erate through the‘ generator. The motor gener
ator armature current reverses and the ampere
turns of the coil C5 of the reverse current relay
are now in opposition to those of the shunt coil
C6. This causes the RC relay to drop out. The
control generator calibrating ?eld CFI is thus
' deenergized at the contacts ROI and the cali
stat from the circuit now insert the motor rheo
stat in series with the motor shunt ?eld.
The motor regulating ?eld by reason of the
contact members F5 and F6 is now connected to
brating ?eld CFZ is energized at the contacts RC2
functioning in conjunction with the closed back
contacts R3. Most of the adjustable calibrat
ing resistor ARZ is shunted by the contacts R3 to
thus provide, for example, a higher permissible
decelerating current than the previous accelerat
ing current. When the braking current ap
proaches the limit established by the setting of
the adjustable calibrating rheostat ARZ, the CR
relay is su?iciently energized to close and con»
nects the control generator to the motor regu
lating ?eld. Since the voltage of the control gen
the control generator so that its ampere turns
are cumulative with the ampere turns of the
motor shunt ?eld MSF. The action of the con
trol generator on the motor regulating ?eld now
erator is now reversed due to the reversal of
motor armature current, current is circulated
through the motor regulating ?eld so that its
ampere turns are in opposition to the ampere
turns of the motor separately excited ?eld, there~
prevents the motor ?eld flux from changing too
by preventing the motor ?eld ?ux from building
rapidly and so limits the accelerating current to
the prcestablished value. It should be noted that
now the control generator is connected to both
up too rapidly and so limits the braking current.
Since the rheostat was turned to a speed set
This closes the con
ting at reduced generator voltage, the rheostat
interlock RI opened and deenergized the main
or pickup coil on the relay TR. The short in
herent time element of the TR relay prevents it
tact members VRI, thereby shunting the genera
from opening immediately, thus holding it closed
tor’ rheostat from the circuit and exciting the
generator separately excited ?eld GSF at its
maximum voltage. The contact members VRZ
open and disconnect the generator regulating ?eld
from the control generator at the same time the 75
until the control generator has sufficient time to
the motor and generator regulating ?eld.
As the
generator voltage approaches its maximum value,
the voltage relay VR closes.
generate a current
in
the reverse direction
through the motor regulator ?eld and the TR
holding coil C l. The TR, relay is now held closed
by its holding coil. As the motor approaches its
‘2,406,426
full field’ speed, the braking current decreases
until the relay CR opens and deenergizes the mo
tor regulating ?eld and the TR relay holding
coil. The TR relay drops out deenergizing the
voltage relay. The voltage relay upon opening
.10
tations are to be determined from the scope of
the appended claims.
‘I claim as my invention:
1. In a variable voltage drive, the combina
tion of, a motor, a main generator for supply
ing electrical current to the motor, a regulating
?eld winding for the motor, a regulating ?eld
winding for the generator, an auxiliary genera
tor, ?rst electrically operated means responsive
to the current of said motor and to the electrical
output of said auxiliary generator, second elec—
lating ?eld. The motor regulating ?eld, how
trically operated means responsive to the elec~
ever, yet remains connected through the contacts
trical‘output of said main generator, third elec
FWI if the relay FW is yet su?‘iciently energized
trically operated means responsive to the electri
by the main generator voltage. The braking cur
rent again increases due to the ?eld flux of the 15 cal output of said main generator, said ?rst means
when electrically operated cooperating with said
generator decreasing. The current relay CR. thus
second means when not electrically operated to
again picks up connecting the control generator
electrically connect the regulating ?eld winding
to the generator regulating ?eld. Since the con
of the main generator to the auxiliary generator,
trol generator voltage is still reversed, current is
circulated through the generator regulating ?eld 20 said third means when electrically operated co
of its back contact members VRI inserts a portion
of the rheostat GR in series with the generator
shunt ?eld and at its contact members VRZ and
VR3 transfers the control generator circuit from
the motor regulating ?eld to the generating regu
operating with said ?rst means when electrically
operated to connect the regulating ?eld winding
direction as those of the separately excited ?eld
for the motor to said auxiliary generator, and
before it was deenergized. The action of the con
said second means when electrically operated dis
trol generator is, therefore, to slow down the
decay of ?ux in the generator and so limit the 25 connecting said main generator regulating ?eld
winding from said auxiliary generator and elec
braking current. As the motor approaches the
trically connecting the motor regulating ?eld
lower set speed, the braking current decreases.
winding to the auxiliary generator independently
The CR relay drops out deenergizing the gener
of said third means.
ator regulating ?eld. The motor armature cur‘
2. In a variable voltage drive, the combination
rent reverses itself and settles down to the load 30
of, a motor, a main generator for supplying elec
current in a direction to operate the motor in the
trical current to the motor, an auxiliary gen
forward direction'.
erator, and magnetic controller means respon~
Now assume the motor is running at some weak
sive to the electrical quantities of said motor and
?eld speed and the stop push button is pressed.
so that its ampere turns are now in the same
The LV relay is deenergized and drops out deen 35 said main generator for electrically connecting
said auxiliary generator during operation of said
ergizing the main coil of the TR relay as well as
motor from zero speed to running speed, to ef
the coil of the F contactor. As the generator
fect a control of ?rst, said main generator, sec
voltage declines the W relay drops out shorting
ond to e?ect a control of both said main genera
out the portion of the rheostat in series with the
motor ?eld MSF at its back contacts FW 2. The 40 tor and said motor and third, to effect a control
only of said motor.
action is the same as though the rheostat were
3. In a variable voltage drive, the combination
turned back as previously described. However,
of, a motor, a main generator for supplying elec
when the VR relay opens it now deenergizes'the
trical energy to the motor, means for controlling
generator ?eld GSF completely, since, substan
tially at this time the forward contactor F drops 45 the speed of said motor, an auxiliary generator,
out opening its contact members FI and F2 re
quired to complete the energizing circuit for the
?rst means responsive to the motor current and
the electrical output of the auxiliary generator,
second means responsive to the main generator
voltage, third means responsive to the main gen
braking current and the generator voltage also 50 erator voltage, said ?rst means and said second
means cooperating under certain operating con
decrease. The current relay CR drops out de
ditions of said motor to connect said auxiliary
energizing the generator regulating ?eld and then
generator to said main generator, said ?rst, sec~
the braking relay BR drops out connecting the
0nd and third means cooperating under different
generator differential ?eld across the generator
armature, since the contacts LVI are now closed, 55 operating conditions of said motor to connect said
auxiliary generator to both said generator and
thus bringing the motor to rest and preventing it
said motor and said ?rst and second means co
from creeping.
operating under other operating conditions of
The reversing cycle of the system is substan
said motor to connect said auxiliary generator
tially the same as that described in conjunction
with forward operation, the reversing contactor 60 only to said motor.
4. In a variable voltage drive, the combination
R as previously mentioned reversing the connec
of, a motor, a main generator for supplying elec
tions of the main generator separately excited
trical energy to the motor, an auxiliary generator
?eld GSF and the motor regulating ?eld. The
for effecting a control of the motor current, ?rst
coil C1 of the ?eld weakening relay FW is also 65 means for selectively exciting the auxiliary gen
reversed in polarity ‘during reversing operation of
erator with a predetermined electrical quantity for
the motor, since the motor armature voltage is
accelerating and braking of said motor, second
reversed. Thus to make the action of the two
means for exciting the auxiliary generator ac
coils cumulative, it is necessary to reverse the coil
cording to the motor current in opposition to
C8 to excite it in the same direction as the re 70 either of the ?rst mentioned selectively obtained
versely excited coil C1.
excitations, and means operable when the ex
The foregoing disclosure and the showings
citation resulting from said second means pre
dominates that of said ?rst means for connect
made in the drawing are merely illustrative of the
ing the auxiliary generator to said main gen
principles of this invention and are not to be
interpreted in a limiting sense. The only limi 76 erator.
generator ?eld GSF. The motor now continues to
brake down to near zero speed. Meanwhile the
11
2,406,426
5. In a variable voltage drive, the combination
of, a motor, a main generator for supplying elec
trieal energy to the motor, an auxiliary generator
for effecting a control of the motor current, means
for exciting said auxiliary generator in accord
12
of, a motor, a main generator for supplying elec
trical energy to the motor, an auxiliary genera
tor for effecting a control of the motor current,
means for exciting said auxiliary generator in ac
cordance with the motor current, means for pro
ducing a standard excitation in opposition to the
excitation according to the motor current, and
means operable when the excitation according to
the motor current is the predominating excitation
ance with the motor current, means for produc
ing a standard excitation in opposition to the
excitation according to the motor current, and
means operable when the excitation according
to the motor current is the predominating exci 10 for selectively connecting the auxiliary generator
tation for connecting the auxiliary generator to
to the main generator, to both the main genera
the main generator.
tor and the motor and only to said motor.
6. In a variable voltage drive, the combination
GEORGE E. KING.
Документ
Категория
Без категории
Просмотров
0
Размер файла
1 022 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа