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Патент USA US2132179

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0a. 4,v 193s.~
H. MILLIKEN
-
’ ' 2,132,179
SYSTEM ‘FOR OPERATING ALTERNATING CURRENT SWITCHBOARD INSTRUMENTS
Filed June 27, 1934
3 Sheets-Sheet l
Oct- 4, 1938.-
H. MILLIKEN
2,132,179
SYSTEM FOR OPERATING ALTERNATING CURRENT SWITCHBOARD INSTRUMENTS
Filed June 27, 1934
I
3 Sheets-Sheet 2
IEP ~ LINE T0 NEUTQAL voLTA<5E_
A
I = J'HOKT CiRculT =CURKENT IN ‘PKlMAKY OF
>e
CURRENT POTENTIAL TRAN/FOKMEK,
E5 -VOLTAGE INDUCED 1N J'ECONDARV OF
CURRENT POTENTIAL TRAN/FORMER.
5'51- =D|TTO ‘KEVEK/ED BY REVEKSING THE
WHQEJ,‘ BRTNGlNG .E5r lN 'PHAJE
I
WITH .Ep.
"E? *HEVKE REPQEJENTJ THE ACTUAL
4*
LINE T0 NEUTKAL VOLTAGE d/‘ALJ'O
THE JEco'NDARv VOLTAGE OF THE
POTENT|AL TRANJ’FORMEK WHICH If
JU'BJTANTTALLY IN vHAJE WITH \1'?
'
x
Kw 7
I/)(=‘KEACT\VE COMPONENT LAG!‘ so°B;H\ND
E/ _
Ifc :CURRENT THROUGH CONDENJ'ERJ‘
11° .
LEAD/E] BY so°
APPROXIMATELY NEUTRAUZE/
THE LAGGING COMPONENT OF CUQQENT IN JEQCOND
—Al(v com, THEKEBY REDUCING THE TOTAL CURRENT
EJ-
J‘UPPLIED BY THE JECONDAPQ/ conL OF CURRENT
‘$2
POTENTIAL TRANJFOKMEKYTHE VOLTAGE DP\o\>/
“16
To A
MTN‘IMUM.
2,132,119
Patented Oct. 4, 1938
I
UNITED STATES PATENT OFFICE
2,132,110
SYSTEM FOR OPERATING ALTERNA'I'ING
CUB-BENT
INSTRUMENTS
Humphrey: lliliiken, Montreal, Quebec,
Canada
Application June 27, 1.34. Suial No. 732,738
s Claims. (01. 111-95)
This invention relates. to the transformation breakdown are'practically eliminated by sepa
of alternating current and its utilization for the rating the secondary winding 5 from the pri
purpose of actuating instruments such as relays.
ammeters, wattmeters,.power-factor meters, etc.
CI
'
1
My invention will be more. clearly described
with the aid of the accompanying drawings
forming part of the speci?cation, wherein
Fig. i represents schematically one form of
my current. transformer;
Fig. 2 represents structurally the arrangement
mary 4 far enough for safety with no insulation
other than air. The path of the magnetic flux
may be partly of iron with air-gaps or entirely
in air with no iron.
A large proportion of the
magnetic ?ux induced by the primary current
does not pass through the secondary coil 5, but
this coil has a large number of turns (several
thousand) of ?ne wire and may readily be de- 1.
of coils in my current transformer;
signed to generate 100 volts or more with maxi
‘Fig. 3 shows schematically the arrangement of
the primary winding of the current transformer
mum primary current ?owing. The instruments
3, C, D, E, G, H, and J connected in circuit with
and a short-circuited additional winding to in
the secondary coils l have coilsv of high imped
15 crease the linkage ?ux;
*
Fig.4 shows schematically an arrangement of
current transformers for use in connection with a
circuit-breaker for'voltages above 154,000;
Fig. 5 shows a circuit diagram of a system uti
my invention;
O lizing
Fig. 6 is a graph illustrating the phase of volt
' age and current in directional relay E utilized ac
cording to my invention;
Fig. 7 is a graph illustrating the phase of volt
ance (several thousand ohms) in place of the "
usual "current" coils having impedance as low
as possible. Such high impedance coils draw
very small currents (a few hundredths of an am
pere) from the secondary winding and therefore
do not reduce the terminal voltage of the sec
ondary winding to an objectionable extent. ”
Condensers (1" may be connected in multiple with
said instrument coils to neutralize the lagging
component of current and minimize the voltage
25 age and current in the secondary circuitof my . loss in said secondary circuits, or the condenser 25
current transformer.
Apparatus heretofore used for‘ this purpose,
designated as current-transformers or series
transi’ormers, have a magnetic circuit composed
30 of laminated steel which completely encircles
one or more turns of the primary circuit, and a
may be connected in series with the instrument
coil and thereby raise the voltage across the in
strument coil.
The secondary I therefore de- .
livers to the instrument a voltage which is close
ly
thisproportional
system the instrument
to the primary
B usedcurrent.
for measuring
With
secondary winding having a much greater num
ber of turns of smaller wire wound around the
ing current voltmeter having the usual “poten
steel core, evenly distributed over the core, so
tial" coil of high impedance, but with a scale
35 as to minimize the leakage of magnetic flux,
which leakage introduces error in the current
measurement. The load connected to the sec
graduated in amperes, and properly calibrated.
ondary winding must have minimum impedance
which limits the distance between. the current
40 transformer and the switchboard instruments,
limits the number of such instruments on one
transformer, and requires relativelyheavy wires.
Such transformer design requirements necessi
the current in the primary circuit is an alternat
Distances of one thousand feet or two thousand, “
feet from the switchboard to the instrument
transformer oil'er no obstacle with this system,
since the current transmitted is so extremely
small. This is advantageous in the design of ‘0
large hydro-electric generating stations.
‘ 1
There is a phase angle of ‘almost ‘exactly 90"
between the primary current I and the voltage
tate very close proximity of the primary winding
Es induced in the secondary. With this system, .
therefore, an instrument C constructed like an
secondary winding which must be grounded for , ordinary wattmeter (substituting a "potential"
,- 45 (usually of high voltage) to the steel core and
protection of operators. Such close proximity
subjects the insulation to high unit stresses and
- there have been many insulation failures of such
current-transformers. The insulation of such‘
transformers for the higher commercial voltages
is also quite costly.
This invention provides means for overcoming
the above described limitations and objectionable
“ features. The cost of insulation and danger of
coil in place of the usual "current" coil) will be
the means of measuring the wattless component,
and an instrument D constructed like an ordinary
wattless component meterdwill measure the watts w
in the circuit. Directional relays (reverse-power
relays) E ordinarily used to open circuit-break
ers when a'short circuit occurs on one side of a
station but not to open the breaker if the short
circuit is on the other side, can be advantageously “
.
2,132,179
2
operated with this system ; short-circuit currents
I usually lag nearly {20° behind the line-to-neu
tral voltage Eb; the" voltage Es induced in the
secondary 5 lags another 90°, making it lag nearly
180° behind the line-to-neutral voltage Ep, and
by simply reversing the two wires at the relay E,
the potentials on the two coils are brought
in phase and the two relay coils are made to ex
ert a maximum attraction to close the relay con
10 tacts when they should be closed and a maximum
repulsion to hold the contacts open when they
should be held open. ‘Pilot-Wire relays Gare
operated more readily with this system than
» with the current-transformer system heretofore
15 used, because it is a simpler matter to balance
two potentials (in two stations several miles
apart) than to balance two currents in secondary
around the magnetic circuit as- shown. The
greater part of the magnetic ?ux induced by
coils I does not reach the bottom steel member 3
and secondary coils 5, but follows shorter paths, >
through the air as shown by the arrows. A suf
?cient portion of the ?ux, however, passes through
the secondary coils 5 to induce a, voltage suitable
for the purposes described. The secondary coils
are preferably placed in the inclined position
shown for the purpose of enclosing a portion of 10
the leakage ?ux which would otherwise not pass
through them.
'
- While I have referred to the device shown in
Fig. 2 as a transformer, it isin fact a low voltage
producing means interposed in‘ the main line con
ductors. The primary coils are in effect trans
mitting coils and the secondary coils are in effect
receiving coils so spaced from the primary coils
as to receive only‘ a selected portion of the mag
circuits in the two stations.
With this system it is a comparatively simple
matter to operate‘ selective relays of the well netic ?ux induced by the primary coils. It is only
known impedance type (or “distance” type) H 1 this selected portion of the magnetic ?ux which 20
in'which a current coil exerts a pull to close the is effective to produce the low voltage in the re
relay contacts (and open the circuit breaker) ceiving or secondary coils.
and the potential coil opposes and delays the
The two coils 6 are for the purpose of opposing
closing of the contacts. The peculiar function of
a portion of the leakage ?ux thereby increasing
“distance” relays is to operate and open ?rst the somewhat the useful portion of the flux, in cases 25
circuit breakers which are nearest to the fault where this is desirabledue to wide separation be
and thus clear only the faulted section of the sys
tween the primary andsecondary coils for the
tem, leaving other sections in operation. With higher commercial voltages. Each of the coils
this system it is feasible to simplify such relays by 6 is short-circuited on itself and bent into the
combining the two coils into one, since it is now peculiar shape as shown; the only current in coils so
simply a matter of balancing one voltage against ' 6 is that induced by the‘ leakage ?ux which they
another (one voltage representing thev line cur
rent and the other voltage representing the line
Bundles of transformer steel laminations ‘I may
voltage) and the two secondary voltages are al
be secured to the structural steel members 2 and 85
most in phase (when there is a short circuit on 3 respectively'as shown in order to increase the
oppose.
the
line).
‘
‘
r
The structural arrangement of my current
transformer A takes different forms suitable to
> the equipment with which it is associated. Where
reactor coils are used for limiting the short-cir
cuit current in a circuit (which is common prac
tice) the reactor coil 4' (having no iron in its
‘magnetic circuit) may be used as the primary
coil of the'current transformer; the secondary
coil 5 may be located in-any position where a
su?lcient portion of the primary ?ux will pass
through it and far enough for safety with no in
sulation other than air between the two coils.
Fig. 1 shows the secondary coil 5 near one end of
the reactor coil 4' and co-axial with it.
Fig. 2 is an elevation (partly in section) of the
transformer A as it is ‘applied to any apparatus
having two or more stacks of pin-type insulators
I for supporting the apparatus, for instance a
power circuit-breaker. The porcelain insulators
I are of a type commonly used, having iron pins
and iron caps, which are therefore magnetic. A
structural steel member 2 supported by cast
iron pedestals 1a joins the two stacks at the top
and another steel member 3 at the lower ends.
These iron and steel parts,v which may support
other apparatus, also serve to carry a portion of
the magnetic ?eld from the primary coils 4 at
the top, through the secondary coils 5 around the
bottom of the stacks, thereby increasing‘ the
voltage induced in coils 5 with a given current in
the primary. The primary coils 4 shown in sec
tion in Fig. 2 and in plan (diagrammatically) in
Fig. 3, are preferably made of thin wide copper
bars bent into spirals and insulated from the ad
jacent parts supporting the coils. The two coils
4 are connected in series with the main high-ten
sion line, with such polarity of connection as to
75 produce magnetic flux in the same direction
total magnetic flux.
,
.
.
,
V
.
‘
Fig. 4 shows diagrammatically current trans
formers arranged in another form for voltages
above 154,000 volts.‘ In this form, the stacks of
insulators are much longer on account of the
higher voltage, and are placed in diagonal rela
tion to act as braces and eliminate bending
‘stresses on the stacks. This diagonal arrange
ment is advantageous magnetically. The three
primary coils 8, 9 and I0 are connected in series 45
with their polarity such as to induce ?ux in the
direction shown by the arrows. There are six
stacks of insulators numbered I I to IS. The ar
rangement is shown diagrammatically developed
into one vertical plane. Actually the three top
junctions of the three ‘pairs of stacks are located
at the corners of a triangle inithe steel plate 2,
and the three bottom junctions of the stacks are
likewise located at the corners of another triangle
on steel structure 3. Stack II thus vjoins stack .55
I6 at the top. Coil 8 encircles stacks I 2' and I3
inducing ?ux downward in them. Coil 9 encircles
stacks I4 and I5 inducing ?ux upward in them.
Coil I 0 encircles stack I6 only inducing ?ux
downward in it. No coil encircles stack II and 60
the ?ux in it is only that returning upward from
the downward ?ux in stack I2. The ?ux in
stacks II and I2 is not utilized. Secondary coil
I'I utilizes the ?ux in. stacks I3 and I4 and coil
65
I8 utilizes the ?ux in stacks I5 and I6.
I claim:
1. In a high-potential alternating-current sys
tem, main-line conductors; a low voltage-produc
ing means interposed in the main line and com
prising a primary or transmitting coil of a small
number of coils in series with the main-line con
ductors, a secondary or receiving coil of a large
number of coils, means for spacing and insulating 1
said secondary coil from the primary coil to locate
said secondary coilin the outer portion of the ?eld 75
9,139,170
of magnetic iiux induced by the primary coil and
coil and provided with an instrument coil having
to form an air gap oi substantial area between
a high impedance, and a condenser shunted across
the instrument coil.
3. In a high-potential alternating-current sys
the said two coils, whereby a substantial portion
01’ the magnetic ?ux induced by the primary coil
will be ineiIective and will ?ow through the air
tem, main-line conductors; a low voltage-pro
ducing means interposed.in the main line and
gap between the two coils and only a selected por
tion of said ?ux will pass through the secondary
comprising a primary or transmitting coil of a
small number of coils in series with the main
line conductors, a secondary or receiving coil of
a large number oi.‘ coils, means for spacing and 10
coil to induce a low voltage therein, and an in
strument in circuit with said secondary coil.
2. In a high-potential alternating-current sys
tem, main-line conductors; a low voltage-produc
ing means interposed in the main line and com
insulating said secondary coil from the primary
coil to locate said secondary coil in the outer por
tion of the ?eld of magnetic ?ux induced by the
primary coil and to form an air gap of substan
tial area between the said two coils, whereby a
substantial portion of the magnetic ?ux induced 15
by the primary coil will be ineffective and will
?ow through the air gap between the two coils
and only a selected portion of said ?ux will pass
through the secondary coil to induce a low volt
age therein, an additional winding for each pri 20
prising a primary or transmitting coil of a small
number of coils in series with the main-line con
15 ductors, a secondary or receiving coil of a large
number of coils, means for spacing and insulat
ing said secondary coil from the primary coil to
locate said secondary coil in the outer portion of
the ?eld of magnetic ?ux induced by the primary
coil and to form an air gap of substantial area
between the said two coils whereby a substantial
portion of the magnetic ?ux induced by the pri
mary coil will be ineil‘ective and will ?ow through
the air gap between the two coils and only a
selected portion of said ?ux will pass through
the secondary coil to induce a low voltage therein,
and an instrument in circuit with said secondary
3
mary coil insulated and closed on itself and so
positioned in relation to its associated primary
winding as to increase the linkage ?ux between
the primary and secondary windings, and an in
25
strument in circuit with said secondary coil.
,
HUMPHREYS MILLIKEN.
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