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Патент USA US2411476

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NOV. 19, 1946.
z_ 0, ST_ PALLEY
2,411,475
LOAD-RATIo-CONTROL CIRCUIT
Filed Aug. 1o, 1944
Fig. 5.
Fig. l.
ìmvemtor:
zmstan o. 51:. P Heb/9
by
»J
Patented Nov. 19, 1946
2,411,476
UNÍTED STATES PATET OFFICE
2,411,476
LOAD-RATIo-ooNTRoL omcm'r
v.Z‘olttm O. St. Palley, Pittsfield, Mass., assigner to
General Electric Company, a corporation of
New 'York
Application August' 1o, 1944, sarlat No. 548,905
1i) Claims. (ci. ivi-miie)
This invention relates to load-ratio-control cir
cuits and more particularly to improvements in
heavy-duty load-ratio-control circuits such as are
used for speed control on powerful electric loco
rnotlves.
`
The ratio of a transformer while under load
can be varied by changing tap connections on
either the high voltage or the low voltage wind
ing. One 'objection to tap changing on the low
voltage side is that in large-size transformers the
lon“ voltage current becomes excessively high,
thereby requiring a large and expensive copper
cross-section for carrying the current.
ln accordance with this invention the load is
divided into groups which, while using the same
at diñerent parts of their voltage range,
never use the same taps at any one time. In this
tray the maximum currents, and hence the cop
per areas, are substantially decreased. This is
es ecially practical in the case of electrical loco
motives in which there are usually a plurality of
equal voltage traction motors which can con
veniently he divided into groups. Another fea
ture of a modined form oi the invention utilizes
single balancing transformer for increasing the
number or" voltage steps for each load and also
i‘or reducing
.switching duty or" the tap chang
ers :for each load.
¿in object ci the invention is to provide a nevf
and improved load-ratio--control circuit.
rfinotl'ler object ci the invention is to reduce the
tan ch wer currents in heavy/»duty load
ï‘atî
Ael c_icuits, particularly those circuits
n
d which are interlocked or tied together by a
suitable common operating mechanism indicated
schematically at 9. The remaining terminals of
the armatures are connected directly to equally
spaced taps in the winding l. rl‘he spacing of
these latter taps may either be equal to the spac
ing o1' the taps 2 or may be diiîerent therefrom
but they are preferably equal to each other.
The operation of Fig. l is as follows: Assuming
that winding l is energized either inductively
from another winding or directly by connection
to a supply circuit, in which case Winding i would
act as an autotransîormer, it will beissen that
thevoltages voltages applied to the motor arma
tures are all equal and that the common oper
ating mechanism 'for the tap changers is in its
minimum voltage position. If now this operating
mechanism is moved vertically upward so that
the tap changers make contact with the next
uppermost trio of taps the voltage of all of the
25 motors will be raised by the voltage difference
In
between
that position
electrically
the adjacent
lowerrnostones
tap ofEl will
the taps
not be
used and the next lowerniost tap
which pre»
vlously had served to energize the armature 1l,
will novv serve to energize the armature
with a
voltage which is one tap higher. Similarly, the
athird
higher
tap‘irom
voltagethe
to bottoni
the arma
will:ure
nowil, serve
whereas
to nre~
is performed; on the low
\ 4¿e side ci the transformer.
ture
viously itlnhad
thissupplied
manner,the voltage
the tapfor
changers
the a are
further object of the invention is to provide
«.
transformer arrangement for
oi circuits for simultaneously in
(D
preferably similar motors having equal voltage
ratings. One terminal each oi armatures 3, Il
and 5 is connected respectively to different ones
of the taps i by :means of ratio adjusters i5, 'l and
er of voltage steps and decreas
switchlrf’ :iuty on ratio adjnsters having
...j
better understood from
.
lon taken in connection with
drawing .and its scope will be
appar-dei claims.
‘ '
"
einhcíli
moved un vardly one tap at a time the voltage of
each
'ature will be changed by the serie
amount and
will be noted that in no pos on
are any two armatures eLergiZed from the saine
tap, although. in dinîerent positions the saine tan
serves to energize different motors.
Referring now to Fig. 2 , the
inding i" is
`
indi
cated as the low voltage secondary Winding of a
main power transformer having a high voltage
primary winding
c
o
~
een ground
ates diagrammatiu
nt oi the invention,
nent, and
3 is a
¿ne the operation ci
and
f
o/“l
‘
“
"
e "lumber
"
ruote
rma
, .i
l
the _motor
motor
a motor I l connec‘
'
i
lei
tu
drawing and more par“
there is shonm therein a main
l which is provided with
being indicated in simplifica scheine-.tic forni as
of loads indicated as the
being sequentially operated
accordance with
the table shown in Fig. 3 by any suitable common
with the niet-or o. The tajo changers
`_ ot
in Fig, l, are shown as constituting a p al
or"
l- which may or may not be
` ily, Energized from wind~ (j. contactera ifi-3i, inclusive, these contactcrs all
” electric motors which are
interlocking or operatingmechanisrn.
5
anatre
plurality of loads, means for connecting each
ioad across a different part of said winding by
way of two different- taps so that each tap cer
ries only the current of one load, and tap
changing means for selectively connecting said
«, loads across varying portions of said winding by
way of dilîerent taps.
2.1m combination, a transformer having a
winding provided with a plurality of taps, e.
plurality of loads, means for connecting each
load across a different part of said winding by
way of two different taps so that each tap carn
ries only the current of one load, tap~changing
means for selectively connecting said loads across
varying portions of said winding by way of dii
ierent taps, there being separate tap-changing
means for each load so that each tap-changing
means carries only the current of one load, cer
- tain of said taps being connected successively to
different ones of said loads by way of diiîerent
ones of said tap-changing means as a result oi
the operation of said tap-changing means.
3. An electric locomotive speed>v control sys-l
tem comprising, in combination, a voltage step
` down power transformer having a secondary
circuit with said tap changers, and means con
nected to said main transformer for varying the
excitation of said balancing transformer.
7. 1n combination, a main transformer having
a winding provided with a plurality of taps, a
plurallty'of loads, separate tap changers for re
spectively connecting said loads across variable
portions of said winding by way oi diiîerent taps,
said tap changers having bridging positions
wherein they simultaneously make connection
with adjacent taps and thus allow a circulating
current 'to flow in said winding between said ad
jacent taps, a balancing transformer having a
plurality of secondary windings connected re
spectiveiy in circuit with said separate tap
changers, and means for variably exciting said
balancing transformer so as to provide load volt
ages intermediate the voltages of said taps and
so as to produce balancing transformer sec
ondary winding voltages equall to the voltage
between adiacent taps for eliminating said cir
culating current and reducing arcing of said tap
changers.
8. _a transformer having a winding provided
with a set of spaced taps, a plurality of tap
winding provided with a plurality of electrically 25 changers for respectively making selective corrn
spaced taps, a plurality of traction motor groups
` each having a terminal connected to a different
point on said winding, and means including
separate tap-changing means for respectively
connecting said motor groups across variable
portions of said secondary winding by way «of
diiîerent ones of said taps so that no tap and
tap-changing lmeans carries more than the cur
rent of one motor group.
nection with the taps of said set, common oper~
ating means for said tap changers which main
tains a predetermined fixed voltage relation be
tween said tap changers, and a plurality of loads
_ each having a pair of terminals, one or" said term
minals of each load being connected respectively
to a different one of said tap changers, the other
vterminal of each load being connected respec
tively to a different point on said winding.
9. A transformer having a winding provided
with a set of equally spaced taps, a plurality ol
4. An electric locomotive speed control system
comprising, in combination, a voltage step-down
power transformer having a secondary winding
tap changers for respectively making selective
provided with a plurality of electrically equally
connection with the taps of said set, each of said
spaced taps, a plurality of equal voltage traction 40 tap changers having a load current terminal,
motor groups each having a terminal connected f
to a diiîerent point on said winding, and means
including separate operatively interlocked tap
common operating means for said tap changers
which maintains a predetermined ñxed voltage
relation between said load current terminals, and
>a plurality of loads each having a pair oi termi
motor groups across variable equal portions of -' nals, one of said terminals of each load being
said secondary winding by way of diiîerent ones
connected respectively to a load current terminal
of said taps so that no tap and tap-changing
of a different tap changer, the other terminal of
means carries more than ‘_ the current of one
each load being permanently connected respec
motor group.
tively to a different point on said winding, the
5. In combination, a main transformer having 50 voltage relation of said points being the same
. a winding provided with a plurality of taps, a
as the voltage relation between the load current
plurality of loads, separate tap-changing means
terminals of said tap changers.
for respectively connecting said loads / across
10. A transformer having a winding provided
variable portions of said winding by way of said
with a set of electrically equally spaced taps,
changing means for respectively connecting said
taps, said tap-changing means having bridging
three tap changers for respectively making con
positions in which they make simultaneous con
nection with the taps of said set in such a. man
nection with diiîerent taps whereby a circulat
ner that each tap changer normally makes con
ing current flows in said winding and tap~
nectlon with but one tap at a time while differ
changing means, a balancing transformer having
ent tap changers make connection with the same
a plurality of secondary windings connected re 60 tap at diüerent times, each of said tap changers
spectively in circuit with said tap changers, and
having a load current terminal, common operat
means for varying the excitation of said balanc
ing means for said tap changers which main- ing transformer.
.
'
tains a predetermined fixed voltage relation
6. In combination, a main transformer having
between
said load current terminals, three loads
a winding provided with a plurality of electrically
each having a pair of terminals, one of said
equally spaced taps, a plurality of loads, separate
tap-changing means for respectively connecting
said loads across variable portions of said wind
ing b_y way of different ones of said taps, said
terminals on each load being connected respec
tively to a dimerent one of said tap changer load
current terminals, the other terminal of each
load being connected respectively to a different
tap-changing means having bridging positions 70 point on said winding, the voltage relation be
in which they make simultaneous connection
tween said points being the same as the voltage
with diilîerent taps whereby a circulating current
relation between said tap changer load current .
flows' in-said winding and tap-changing means.
terminals.
a balancing transformer having a plurality of
~
ZOLTAN 0; ST. FAIL-EY.
secondary windings connected respectively in 75
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