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Патент USA US2404982

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July 30, 1946-
J. B. OWENS ET AL
2,404,982
RELAY CONTROL CIRCUIT
Fi'led Jan. 13, 1945
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INVENTORS
, JamesB. Owens and?
' leoberz’ih’.
Hz'z‘son.
BY
'
ATTORNEY
Patented July 30, 1946
2,404,982
UNITED STATES PATENT OFFICE
2,404,982
RELAY CONTROL CIRCUIT
James B. Owens and Robert H. Hitson, Wilkins
burg, Pa., assignors to Westinghouse Electric
Corporation, East Pittsburgh, Pa., a corporation
of Pennsylvania
Application January 13, 1945, Serial No. 572,703
4 Claims. (01. 175--320)
1
2
Our invention relates to circuits for controlling
cally with respect to the coil so that in the open
position of the relay a resonant rise in voltage
the operation of electromagnetic relays.
In automatic switching or relay equipment, it
is often desirable to cause a contactor or other
electromagnetic relay to drop out by short cir
cuiting its operating coil. This may be accom
plished by connecting a resistor in series with
the coil in order to limit the short circuit cur
rent. This method, however, requires a consid
erable current consumption when used with re
lays which have a wide inductance variation be
tween the open and closed condition of the ap
is caused in the series circuit, thereby producing
a voltage across the coil which is higher than
the terminal voltage of the relay circuit. When
the relay picks up, the increased inductance of
its operating coil causes the series combination
to depart considerably from resonance so that
the voltage impressed on the operating coil drops
Hence this tuned series arrange
ment provides a high voltage across the operat
ing coil when such voltage is favorable in order
10 accordingly.
pertaining magnetic circuit. With such relays,
to pick up the relay armature and a lower volt
if the resistance in series with the coil is made
age when the armature is in closed position
low enough to allow the relay to pick up from 15 so that such lower voltage is su?icient to
the open position, a rather high current will
hold the relay magnetically sealed. In con
?ow through the coil in the closed position.
trast thereto, the above-mentioned use of a
Similar conditions exist with relays whose mag
resistor in series with a relay coil of greatly
netic circuit has su?lcient residual magnetism to
variable inductance provides a low coil volt
hold tihe armature in closed position after ces 20 age before the armature picks up a higher
sation of the pick-up excitation imposed on the
voltage to hold the armature closed, which is
coil. When such residually held relays are pro
contrary to the favorable conditions afforded by
vided with a control contact for short circuiting
a tuned series capacitor.
the coil after temporary excitation of the coil,
If in a relay controlled circuit according to the
the use of a series resistor for limiting the cur 25 invention the operating coil is ‘short circuited
rent during short-circuit periods of the coil has
after the armature has picked up, the capacitor
also the result of requiring a rather high cur
alone is connected across the terminals of the cir
rent due to the considerable change in coil in
cuit and draws only a low current, for instance
ductance between open and closed relay posi
less current than passed previously through the
tions.
coil circuit.
It is an object of the invention to provide a
Figure 1 of the drawing shows the diagram of
control circuit for electromagnetic relays that
a relay control circuit according to the inven
permits short circuiting the relay coil while op
erating with a low pick-up (open position) cur
rent and also with a low holding (closed-position)
current.
Another object of the invention is to achieve
the just-mentioned advantage by means of cir
cuit devices of simple design and low cost so as
to be comparable, in these respects, with the
above-mentioned use of series resistors.
tion,
!Fig. 2 is a voltage time diagram explanatory of
Lo -VI conditions occurring in a circuit according to Fig.
1; and
Fig. 3 represents diagrammatically another em
bodiment of a control circuit according to the
invention.
Referring to Fig. l, the relay, Whose operation
is to be controlled, has a laminated and substan
A still further object of the invention is to pro
tially E-shaped magnetic ?eld structure I and
vide a relay circuit for alternating-current op
an appertaining armature 2 also of laminated
eration which reduces the burden on the source
and E-shaped design. The armature 2 is mov
45
of control current by securing a more favorable
able vertically with respect to the ?eld structure
power factor than that prevailing in series resis
I against gravity bias and operates a main relay
tor circuits.
contact 3. This contact is shown as represent
An object of the invention is also to devise a
ative of a large number of available contact de_
relay circuit which affords an accelerated pick
vices involving one or several make or break con
up performance on closing without placing an
tacts in any combination needed for the partic
overvoltage on the relay coil.
ular control function to be performed by the re
In order to achieve these objects, and in ac
lay circuit. The movable armature assembly ac
cordance with our invention, we connect a ca
cording to Fig. 1 is further provided with an
pacitor in series with the relay coil to be short
interlock contact 4 and a self-holding contact 5.
circuited and dimension this capacitor electri 55 The control coil ‘6 of therelay, mounted on the
2,404,982
3
stationary ?eld structure I, is connected between
the two terminals 1 of the relay circuit. Series
connected with coil 6 between terminals 1 are
a capacitor 8 and a control contact 9, the latter
being shown as a normally open push-button
contact. Another control contact H1, normally
biased toward open position, is connected across
coil ‘6 in series with the above-mentioned inter
4
able armature l2, both preferably laminated,
which form together a retentive magnetic circuit.
That is, this circuit contains a magnetic material
whose remanent magnetism is su?icient to hold
the armature sealed against the ?eld structure
once the magnetic circuit has been properly mag
netized. The armature i2 actuatesan assembly
of contacts which includes one or several main
contacts, such as the one denoted by [3, and an
lock contact 4.
The magnetic circuit of the relay has negligible 10 auxiliary contact Ht which closes shortly before
armature l2, during its closing movement, reaches
retentive magnetism and is of such type as trade
the end of its travel, or which is time delayed and
velop a considerable change in the inductance of
hence closes only after the armature l2 has abut
coil 5, depending on whether the armature 2 is
ted against the ?eld structure.
in the illustrated dropped position or whether
The ?eld structure i l is provided with two coils
15
the armature is lifted and in engagement with
l5 and it} respectively. Coil I6 is the main oper
the ?eld piece I. That is, the resistance of coil
ating ‘coil of the relay and is connected between
6 to the flow of alternating current therethrough
the
circuit terminals H in series with a capacitor
is low when the armature is in open position and
it and a normally open control contact I9. An
high when the armature is in closed position.
other control contact 2%), normally biased toward
Capacitor 8 and coil ii are rated so that they form
its open position, is connected in series with coil
a circuit combination which is substantially in
55 directly between the terminals 11.
resonance when coil 6 has low inductance but is
When the magnetic parts H and i2 are de
considerably out ‘of tune with the frequency of
magnetized, the armature assembly assumes the
the alternating control current when the arma
illustrated open position under the effect of its
ture is closed and the coil inductance corre 25 gravity or other biasing force. When contact I9
spondingly high.
is temporarily closed, the circuit of coil I6 is com
The closure of contact 5 completes the series
pleted through the series capacitor l8. Capacitor
circuit of capacitor 8 and coil 6 between termi
i8 is tuned as described previously so that a high
nals 1. Assuming the armature to be dropped
initial voltage appears across coil 1 S. This voltage
out as shown, the resonance system is tuned and
suffices to magnetize the ‘magnetic circuit of the
causes a‘high voltage to appear across coil 6. As
relay
so that armature i2 is attracted and sealed
a result, the ‘relay magnet is sufficiently energized
against the field structure it, thereby increasing
to lift vthe armature
This causes a reduction
the reactance of coil 5%. Consequently, at the
in coil voltage, but since a low excitation is re
end
of the armature closing movement, the coil
quired vto merely hold the relay in the closed posi- ,
voltage is reduced to a lower value. The closing
tion, the reduced voltage is again suf?cient for a
contact ill short circuits the coil l6 and thereby
proper relay ‘operation. The closure of armature
terminates the electric excitation of the magnetic
"2 .actuat'es the main contacts of the relay and has
relay circuit. However, the residual magnetism‘
also the effect of closing a self-holding circuit
in this circuit is normally sufficient to maintain
at contact '5. As a result, contact 9 can now be
the relay in sealed condition. If the short circuit
released without affecting the operation of the
at contact Ill should be established at an instant
relay. When thereafter the contact ii! is tem
near the zero passage of the energizing voltage
porarily closed, it short circuits and thereby de
so that the residual magnetism is insuf?cient to
en'ergizes the coil 6, thus releasing the armature
seal thearmature, the movable assembly will vdrop
assembly to move under its bias into the open
position.
The voltage conditions prevailing at vrelay coil
‘6 during the just-mentioned operation of the sys
tem are typi?ed by'the schematic diagram of Fig.
2.
When contact 9 is closed at the moment ‘Tl, .
the coil voltage increases rapidly above the line
voltage applied to the ‘terminals '7 and then de
clines while the armature moves toward the sta
tionary ?eld structure or" the relay. At the end
of the armature movement, a stable coil voltage
is reached which is considerably lower than the
oil so that another magnetizing .and short circuit
ing cycle is initiated and .if necessary repeated
until the armature remains .sealed. The short cir
cuiting of the coil imposes the terminal voltage
across the capacitor is. In order to cause the
relay to drop out, ‘contact 29 is temporarily closed.
This completes the circuit ofcoil l B'urhich is rated
for providing ‘a weak demagnetizing effect. .Con
sequently,:a few voltage cycles 'of the demagnetiz
ing current suliice to reduce the residual magi
netisrn of the relay below the value necessary ‘for
holding the armature in picked-up position. :The
armature assembly will then :follow its bias and
return to the illustrated dropped off position. It
will be ‘obvious that the advantages mentioned
above in conjunction with ‘the embodiment of Fig.
.1 are also realized with relay circuits ‘according to
initial peak voltage and, for instance, somewhat
above the terminal voltage. When the coil ‘5 is
short circuited by closing contact ii! at the time
point ‘T2, the coil voltage drops to zero and the
line voltage is applied across the capacitor 18.
The capacitor draws less current than did previ
ously the capacitor coil ‘combination so that the
Fig. 3.
short circuiting does not have the [effect of in
creasing the current consumption. The presence
of the capacitor in the coil circuit of the ‘relay
has further the ‘advantage vof correcting ‘the
power factor of this circuit and thereby reduces
tion and without ‘departing v'l-rom the'essent‘ial ‘fea
Those skilled in the art‘wi'll further understand
from the foregoing disclosure that the modi?ca
tions as to details and speci?c circuit 'arrange-.
ments can be made within the gist of our inven
the burden imposed von the :current source. Due
tures of the invention, as set forth in ‘the ‘claims
to the steep increase in voltage immediately upon 70 attached hereto.
the closure of the coil circuit, the response of the
We claim as our invention:
relay is accelerated without placing a continuous
1. A relay control circuit comprising, in com
bination, an electromagnetic relay having an
overvoltage on the coil.
armature ‘biased toward open position and a mag
In the ‘modi?cation according to ‘Fig. 3,17he re
lay has a stationary ?eld structure i i and a mov 75 net coil for moving said armature into closed po
2,404,982
5
sition, said coil having low inductance when said
armature is in open position and high inductance
when said armature is in closed position; terminal
means for supplying energizing alternating cur
rent to said coil; a capacitor connected with said
coil between said terminal means and tuned rela
tive to said coil so as to form together therewith
a series circuit which is substantially resonant at
said low inductance and substantially non
resonant at said high inductance; and control
means connected across said coil for short cir
cuiting, when actuated, said coil in series to said
capacitor.
2. A relay control circuit comprising, in com
bination, an electromagnetic relay having an
armature biased toward open position and a mag~
net coil for moving said armature into closed posi
tion, said coil having low inductance when said
armature is in open position and high inductance
when said armature is in closed position; terminal 26
means for supplying energizing alternating cur
rent to said coil; a capacitor series connected with
said coil and said terminal means and tuned rela
tive to said coil so as to form together therewith
a circuit which is substantially resonant at said
low inductance and substantially non-resonant
at said high inductance; a control contact series
connected with said coil and said terminal means
for selectively closing and interrupting the series
6
ing current to said coil; a capacitor series con
nected with said coil and said terminal means
and tuned relative to said coil so as to form to
gether therewith a circuit which is substantially
resonant at said low inductance and substantially
non-resonant at said high inductance; a normally
open control contact series connected with said
coil between said terminal means for closing the
series connection of said coil and said terminal
- leans; a self-holding contact controlled by said
armature and connected across said control con
tact so as to maintain said series connection closed
upon actuation and release of said control con
tact; and another normally open control con
tact connected across said coil for short—circuit~
ing when closed said coil in series with said ca~
pacitor.
‘l. A relay control circuit comprising, in com
bination, an electromagnetic relay having a re
tentive magnetic circuit which includes an arma
ture biased toward open position; a magnetizing
coil inductively associated with said magnetic cir
cuit for causing, when energized, said armature
to move into closed position, said coil having low
inductance when said armature is in open posi
tion and high inductance when said armature is
in closed position; terminal means for supplying
energizing alternating current to said coil; a ca
pacitor connected with said coil between said ter
connection of said coil and said terminal means; 30 minal means and tuned relative to said coil so as
and a normally open control contact connected
to form together therewith a series circuit which
across said coil for short-circuiting said coil in
is substantially resonant at said low inductance
series with said capacitor in order to cause said
and substantially non-resonant at said high in
armature to move under its bias to open position.
ductance; a, contact controlled by said armature
3. A relay control circuit comprising, in com
and connected across said coil for short-circuit
bination, an electromagnetic relay having an
ing said coil in series with said capacitor when
armature biased toward open position and a mag
, said armature is in closed position; and control
net coil for moving said armature into closed
lable means for demagnetizing said magnetic cir
position, said coil having low inductance when
cuit.
said armature is in open position and high in 40
JAMES B. OWENS.
ductance when said armature is in closed position;
ROBERT H. I-IITSON.
terminal means for supplying energizing alternat
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