Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
STAT
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
USE OF LOADING COILS ON CABLES WITH POLYVINYL-CRLC*UDE
EMPLOYED IN INTRARAYON COMMUNICATIONS NETS
yestnik Sv&zi
[Communication News],
No 8, 1953, Moscow,
Pages 15-16
A. I. Semenov,
F'ngineer
The article discusses a method of loading cable lines of intra-
rayon communication and considers a method of mounting the inductance
coils.
At the present time the networks of the intrarayon communication (VRS)
at the present time make widespread use of cables (wire pairs) with poly-
vinyl-chloride insulation. The industry produces such cables under the
trademark PRVPM with copper wires 0.8, 1, and 1.2 mm in diameter. The radio
thickness of the insulation in the cables is respectively 1 ? 0.2, 1.2 ? 0.2,
and 1.4 t 0.2 mm.
The electrical parameters of the nonloaded cables with polyvinyl-chlor-
ide insulation at a temperature of ? 200 are given in Table 1.
f
kc
P OC Z
mnep/km radian/km ohm
Z cos
ohm
-Z sin
ohm
PRVPM-0.8 mm
0.3
88
'0.084
587
42?30'
432
396
(Ro = 72.2 ohm/km;
C - 0.111 mfd/km;
0.8
149
0.141
353
41?24'
265
234
L = 0.816 mh/km)
2.4
237
0.263
207
38?36'
163
128
PRVPM-1 an
(Ro - 47 ohm/km;
0.3
72
0.069
467
42?05'
356
312
C = 0.114 mfd/km;
0.8
115
0.117
290
40?32'
220
188
L - 0.802 mh/km)
2.4
185
0.223
166
35?40'
135
97
PRVPM-l.2 ma
(R - 32.8 ohm/km;
0.3
60
0.059
386
41?41'
289
257
0
C - 0.116 mfd/k54
0.8
96
0.101
237
39?32'
183
151
L - 0.792 mh/km)
2.4
148
0.197
140
32?55'
118
76
According to Rukovodstvc po stroitel'stvu i remontu soorusheniy vnutri-
r&yonnoy sv asi [Instructions for the Constrrction and Repair of Intrarayon
Structures , Part II, 1949, Svyas'isdat, thb attenuation in the section com-
prising the intrarsyon network telephone subscriber set and the interurban
telephone station of the rayon central station should not exceed one nep at
a frequency of 800 cycles, and for certain rayons 1.6 nep at the sage fre-
quency (Figure 1). The maximum length of the line from the telephone not
of the subscriber ml we iutraru9iuu motwork to the int. :sham rayon Contra,.
telephone station, corresponding to these norms, is indicated in Table 2.
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
STAT
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
Table 2
Maximum permissible length of line, in km
Double-step construction
Single-step construction of net of net
u = 0"v aup b 1.6 uop b = 1.G u p
b = 0.5 nep b = 1.1 nep b = 0.85 nep
line .line line
YRVYM-U.6 mm s.aU 1. iU
PRVPM-1.0 mm 4.35 9.55
It is evident fron the table that the maximum telephoning distance us-
ing cables with polyvinyl-chloride insulation does not exceed 11.5 km. Such
a distance is inadequate for rayons with large territories. This distance
can be increased either by installing repeaters, which is difficult in
practice, or by artificially increasing the inductance of the line.
The inductance is usually increased artificially by loading the tele-
phone network. Essentially the method consists of inserting in the cable
line inductance coils at equal distances from each other, as shown schemat-
ically in Figure 2. A loaded line can be considered as consisting of indi-
vidual links, each link containing a coil and a section of cable on each
side.
To load lines on the intrarayon communication networks the Russian
industry produces coils which have an inductance of 70 mh. The loading
spacing S (distance between coils) is taken to be 1 km. Under these condi-
tions the channel occupies a frequency band from 300 to 2,400 cycles.
:'he inductance coil has a cast iron dish (case) with a cover and 2
PRVPII paired lead-in wires. Inside the dish is a toroidal core, made of
pressed powdered magnetodto.eetric. The corn carries a winding made of
insulated copper wire. The core is impregnated with a substance containing
rosin, paraffin, and natural rubber.
The electrical parameters of cables with polyvinly-chloride insulation,
loaded by 70 mh inductances with a loading spacing of 1 km are given in
Table 3.
Type of cable
(Loading system:
L8 . 70 mh,
S . 1 km)
f
kc
mnep/ka
OC
radian/km
Z
ohm
- ~+
Z cos (p
ohm
-Z sin
ohm'
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
0.3
50.4
0.1704
910
16030'
883
258
FRVPY-0,8 ma
20W.
61.0
0.4561
865
8018'
850
125
2.4
100.8
1.4853
1092
5005?
1099
110
STAT
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
0.8 mm diameter be laid over a route 6,810 m long. Dividing 6,810 by 1,000
we obtain 6.81. Consequently the number of spacings will be 7. Hence the
length of the practical spacing will by 6,810: 7 - 973 m, and the length
of half the spacing will be 973:2 = 487 in. Thus the outside coils should be
installed at distances of 487 m from each of the stations and the intermedi-
ate ones at a distance of 973 m from the outside coils and from each other.
Deviations from the selected loading spacing, er;.uld mot oxcccd 2%- For
example, if the loading spacing is one km, the coils should be installed not
closer than 980 and not farther than 1,020 m from each other.
neinre installing the inductance coil one checks that its lead-in wires
conductors and between the coil windings and the cast-iron case is measured.
If a cable with polyvinyl-chloride sheath is laid mechanically, pits
measuring not less than 0.75 x 0.75 m and 0.7 -- 0.8 m c'aep are dug manually
at the locations where the inductance coils are to be installed. The bottom
of the pit is levelled and a recess is formed in it in such a way that the
lead-in wires can be located on the bottom of the pit with a certain amount
of slack (bend).
Using the lead-in conductors, the inductance coil is connected in series
with the wires of the loaded cable, paying particular attention to the thor-
oughness with which the splices are made. The coil and the adjacent cable
sections are then covered with a layer of sifted earth or sand not less than
10 cm thick and is protected against mechanical damage, by bricks, concrete
slabs, boards impregnated with bitumen, etc.
It is best to install the induction coil starting with any one station
and using the following zequence. At the place where the first coil is in-
cgtalled (at a distance of half a loading spacing from the station) the sec-
tion of the cable is checked on the station side for open circuits and for
grounds. Then a previously checked coil is inserted. After this one goes
to the pit in which the second coil is to be installed (at a distance of one
loading spacing from the first coil) and the section cable is checked from
that point back to the station. If the checked section is in working order,
the second coil is connected and the first pit is filled with earth or sand.
The second pit is filled after checking the cable irom the third pit etc.
It is also possible to perform the installation using 2 brigades work-
ing simultaneously from both stations towards each other. However, no
matter what method of organization is used, it is necessary that the route
be measured and that the location of the coils be established beforehand,
using a practical loading spacing previously chosen. If this condition is
not satisfied, the length of the splice section may differ considerably
(more than 2%) from the practical spacing; this will make it necessary to re-
install the coils already installed.
After completing the installation of the induction coils it is neces-
sary to determine by electric measurements the insulation resistance, the
d-c loop resistance, and the asymmetry of the loaded circuit. The document
accompanying the cable should contain the following data: section in which
the cable is laid, length of the section, type of cable, loading system and
number of induction coil installed, date cable was laid. last name of
persons installing the induction coil and results of electrical measurements.
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
STAT
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
STAT
d.4nAQ75np U"-' 0.074%"
0
0
k?br+ki~llne~
$f75Mp,_ Qo7$n 4d75
bcffn.q +b,+ba+bA46q
interurban telephone station of rayon central
central telephone station intrarayon communication
telephone substation intrarayon communication
subscriber's telephone set
line transformer
Figure 1. Distribution of attenuation in intrarayon communication
net. a, b, single-step construction of net; c, 2-step
construction of set.
SfL S S I ~y.~?
~ ~
Figure 2. Diagram of loaded cable line.
Sanitized Copy Approved for Release 2011/05/19: CIA-RDP80-00809A000600120033-2
g07!lfMp C% g C17-4 4In-