H R O TRANSMITTER
RECEIVEK
&
INTRODUCTION:
A
synchro is an
electromagnetic
an
common iy
angular position of a transducer
shaft into an electri
Convert
ne
Dasic synchro
is
usually called
construction is similar
to that of a
Btator
(stationary menber)
is of
synchro
a
three
idnal.
siEO
transmitter. tS
phase alternator
i
silicon
steel
Slotted to acconmodate a balanced laminated
three phase
winding
Hhicn
and 1s
i
usually
in
the
ed.
The
of
concentric coil type(Three
identical
r i t h their axis 120 deEree
apart ) and
i s are
Y connect
coils
Plao
stator
rotor
is
a
dunb bell
centric coi1. an a . c . voltage construction
is
through slip rings.Ref .Fig.No. 1A. applied to
Let
an
and wound with a conthe rotor Wina lnE
voltage
a.c.
Vr(t)
Vr sin Wct. . .(1)
the rotor of the
synchro transnitter.This voltage
causes a floR of nagnetising current in the rotor coil
which
produces a sinusoidally time vary ing flux directed along
its axis
be
supPlied
to
and distributed nearly siusoidally,
in the air gap along stator
periphery.Because of transforner action, voltages are induced in
each of the stator coils.As the air gap flux is
diatributed the flux linking any stator coil is sinusoidaliy
the consine of the angle between rotor and stator proport1onal
coil axis anddto
s o i s the
voltage induced in each stator coil.
The stator coil voltages are of course in time phase with each
other. Thus Re see
that
the synchro transnitter
(TX)
acts
iike
single phase transforner in which rotor coil is the prinary and
the stator coils form three
secondaries.
Let Vsl N ,Vs2 N and Vs3 N respectively be the voltages induced
the stator coils S1,S2 and S3 with
respect to the neutral.Then
for the rotor position of the
transnitter shown in
in
sychro,
fig.No.1 where the rotor axis makes an angle 0 with the axis of
the stator coil S2 .
Let Vs 1N = KVr sin Wct cos 0
+120). . . . . .
Vs2N= KVr sin Wct cos (0)
Vs3N
= KVr s i n Wet
cos
0+240)
(2)
(3)
(4
The three terminal voltages of the stator are
Vs1s2 =
=
Vs2S3
=
Vs1N -Vs2N
3
KVr
Vs2N
sin
(0
+240)
=
Vs3N
=
3
KVr
Hct
(5)
s in Wct
(6)
-Vs3N
3 KVr sin (0 +120
Vs3S1
sin
-
VsiN
sin
(0
)
sin
Wct
.
..(7)
0012
Voltage
is eTO
induced
ITon
equation
(2) and (3)
it
is seen
tnat
naIUd
stator coil s2 while
G
the teTminal
that
l1L0o4
an of
TOtOr 1s defined as the voltage Vs3s1 is zero.This posiio".
electricn1 zero of the Tx and 1s Used a
reterence for
specifying the angu lar position of the
rouo
in the
&
Thus t is seen that the input.
to the synchro transmitter
angular position of its rotor shaft
1s
Chree Single phase voltages given by and the output 1s t
nagnitudes of these
eq.(5),(6) and (7). Tne
voltages are
functions of
The
classical synchro
systens consists
of two
a
e
shaft posIL1ol-
units
.
1.Synchro transnitter (Tx)
2.Synchro receiver (Tr).
The
synchro receiver is having almost
the same
features. The tro units are
constructiona
connected as shown in figure N0.2.
initially the winding $2 of the stator of transnitter is
tioned for naximun couplingg Rith rotor winding. Suppose pos1its
voltage is V. The coupling between S1 and S2 of the stator and
prinary (Rotor) rinding is a cosine function. Therefore the
effective voltages in these Hind ing are proportional to c0s bU
degrees or they are V/2 each. So long as the rotors of the transmitterS and receivers renain in this position, no current R1il
flon between
windings because
of
voltage balance.
When the rotor of Tx is noved to a new position, the voltage
balance is disturbed. Assune that the rotor of Tx is noved
through 30 degrees, the stator winding voltages will be changed
to zero, 0.866V and 0.866V respectively. Thus there is a voltage
inbalance betreen the windings causes currents to lf low through
the close circuit producing torque that tends to rotate the rotor
of the receiver to a nex position where the voltage balance is
again restoreed. This balance is restored only if the receiver
turns through the same angle 'as the transmitter and also the
direction of the rotation is the same as that of Tx.
The TxTr pair thus serves to transmit information regarding
angular position at one point to a
remote point.
SYSTEM DESCRIPTION AND OPERATION.
The systen set up
is nade up of synchro transmitter and synchro
sritches
single rigid base provided with suitable
contains a step doxn
also
piates.The
systen
and anodised angular
test
e x c i t a t i o n to the rotors. Suitable
transforner for provid ing
and S3) for both
stator
(S1,S2
and
points for rotor ( RI and R2)
receiver
on
Tx and Tr
a
are
provided.
00123
OPERATING INSTRUCTIONS:
xperiment No.1 Study of synchro transmit.1or
n
this part of
LOrner
mitteI
the
expt,we can
see how,
because of
the 1.ranS
of synchro
action, the angular position of tlie rotl.or
is transformed into a unique set of stator voLtaEes.
trais-
PROCEDURE:
1.Connect
the mains
provided. Do
supply
to
not connect any
the
systen with
patch cords
to
the
help
of
cable
terninals
marked
voltage
between
"S1,S2 and $3".
2.Switch on nains supply for the unit.
3.Starting from zero
position,note down
the
stator winding terninals i.e. Vsis2,Vs253 and Vs3sl in a sequen
1.1al
nanner.Enter
readings
in
a
tabular
foH
and
plutt
a
grapii
of
angular position of rotor voltages for al1i three phases
coinsides
Note that z e r o position of the stator rotor
4.
VS3S1 voltage equa1 to zero voltage .Do not disturb
t
Witi
this condi-
i on.
Experiment no.
2:Study of synchro transnitter and receiver pair .
PROCEDURE:
1.Connect mains
supply cable
to S1,S2 and $3
2.Connect S1,S2 and S3 terminals of ttransmil 1.er
of synciro receiver. by patch cords provided respectively.
3.Switch on SH1 and SW2 and also Switch on t he mains supply.
4.Hove
the
pointer
i.e.
rotor
position
of
synchro
transmitler Tx
i.n steps of 30 degrees and observe the new rotor position.0bserve
that whenever Tx rotor is rotated, the Tr rolor follows i t for
both the directions of
rotations and
their
positions
are
in
goud
agreement.
5.enter the
1he tabular
input angular position and out.put. angnlar position
forn
and
plot a
graph.
PRECAUTIONS
1.Handle
the
pointers
to
2.Do not attenpt
rotor
3.Do not slhort
tor
Pull
or
both
the
rot.urs
the pointers.
s t a t o r terminaJs.
out
in
a
gent. le
manner
in
Sttur
tu
tutur
Cunslruci iwinal
feul ures ul syuclhio
uusnilier.
.uF'f
ScliclIC
CONSTRUCTIONAL
DETAILS
diigr:l:
ot syiicliru tu illisiuintir
SYICHRO TRANS1IT: ER
OF
FIGURE NO.
1
V
Slatur windinny o
Slulor winding
fronsiller
Receivet
/
Rolor
Rolor windlng of
widing o
Pecevr
rgnsintr
A.C.Line
(u) Torquc
transulssiou
uslug
syucluu'uhnsuiiller.
ReclVe
stolo
lrGnsmitlet
Stutor
n
s6GGO
S70
Recelver
irusnitlr
,
1
Rotor
Rolor
AC.Line
FELLOW
UP SYSTEM OF SYNCHRO
FIGURE
NO.
2
TRAIISHIT.ER
AND RECEIVER
FRONT
PANEL
VIEW
OF
SYNCHR0
SYNCHRo
O
270090
PL
180
aINa
R2
L
ON
R
1) cONNECT S1, s2, s3
SYNCHRO RECEIVER
SW2 ARE
sYNCHRo Tx & TR.
180
OFF
OF
s1
SYNCHRO
TRANSMITTER
RESPECTIVELI
BY MEANS OF
SWITCHES
R
O s2
OO
$3_
LSW1 SW2
&
TR.
RECEIVER
270 90
2) SW1
&
SYNCHRo
TRANSMITTER
NOTE:
TX
FOR ROTOR sUPPLY
TO
$1,
s2,
$3 OF
PATCH cORDS
(EXCITATION)
OF
TOP VIEW OF SYNCHRO
TRANSMITTER & RECEIVER.
STEP
sYNCHR
TX
DOWN
TRANSFOR MER
SYNCHR
TR
FIG.
NO.
3
VERSUS
SYNCHRO TRANSMITTER ROTOR POSITION
PHASE
THREE
FOR
STATOR VOLTAGE
(VSIS3,VSiS2,VS2s3)
SR.
ROTOR
NO. POOSITION
DEGREES
1
00
30
60
90
120
150
180
210
240
| 10.
270
11.
300
12:|
330
RMSVOLTAGE
RMSVOLTAGE
FOR STATOR
FOR STATOR
TERMINAL
TERMINAL
VS3SI
VSIS2
0.1
33.8
58.9
69.1
60.1
60.3
34.5
1.1
33.7
| RMSVOLTAGE
FOR STATOR
TERMINAL
VS2SI
59 8
68.6
60.7
34.9
59.6
0.4
36.2
68.9
32.6
0.9
60.3
593
33.9
34.8
68.9
59.6
59.1
68.8
59.7
33.5
0.3
33.5
60
(FIG NO. 4)
69.2
34.9
0.4
35.1
:
:
TYPICALRESILISEOR
STUDY OF sYNCHRO TRANSMITTER AND RECEiVER.
ANGULAR POSTTION IN DEGREES
SYNCHROTRANSMITTER VP
0.0
30060:090.0
120.0
150.0
180.0
210.0
240.0
10.
11.
12
270.0
300.0
330.0
ANGULAKPUSITION IN DEGREES
3YNCHRO RECEIVER. OP
Q.5
30.5-
61689.0
119.0
148.0
178.0
209.0
240.0
269.0
299.0
329.0
NEAdonTE
R
A
t
ANGULAK
TRANSMITitRSAOE )