Ice melting circuit arrangement for a high-voltage transmission network

A high-voltage network includes at least one overhead power transmission line provided with an insulated conductor,which line connects busbars of transmitting and receiving substations. A source for melting the ice is connected, in the course of ice melting, to at least one disconnected phase of the power transmission line. The insulated conductor is joined during ice melting to at least one disconnected phase of the overhead power transmission line from its opposite ends.

FIELD OF THE INVENTION 
The invention relates to power engineering and, in particular, to a 
high-voltage network. 
The proposed high-voltage network can be employed in areas of severe ice. 
DESCRIPTION OF THE PRIOR ART 
There is known a high-voltage network comprising an overhead power 
transmission line provided with an insulated conductor, which connects the 
supply (transmitting) and intermediate (receiving) substations, and a 
source for melting the ice connected to the heated conductor. 
In this case melting of the ice on conductors of all lines of said 
high-voltage network requires sources for melting the ice at each 
substation, which ensure a specified voltage level and are connected to 
the conductor. 
In some cases the available nominal operating voltage at the substation 
does not correspond to the required voltage for melting the ice on a given 
conductor, which makes melting difficult. 
When, at one of the substations there is no source for melting the ice, the 
icing on the conductor of the overhead line is melted from its opposite 
end, which involves increased insulation of the conductor. 
Besides, in some cases making the circuit for melting the ice on the 
conductor from a voltage source with a specified voltage value requires a 
great number of switchings and presence of duty personnel at each 
substation. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a high-voltage network which 
ensures heating of insulated conductors with less insulation. 
Another object of this invention is to considerably reduce the number of 
sources for melting the ice. 
Yet another object of this invention is to reduce the time for joining the 
power transmission line circuit for melting the ice. 
These objects are achieved by a high-voltage network comprising at least 
one overhead power transmission line provided with an insulated conductor, 
said line connecting busbars of the receiving and transmitting 
substations. A source for melting the ice is provided which is coupled 
during ice melting to at least one disconnected phase of the power 
transmission line. The insulated conductor, according to the invention, is 
coupled during ice melting to at least one disconnected phase of the 
overhead power transmission line from its opposite ends. 
It is preferable that a high-voltage network comprise an overhead power 
transmission line with an insulated conductor, which connects busbars of 
the transmitting and receiving substations and a source for melting the 
ice, which one output of which being connected during ice melting to one 
end of the insulated conductor, according to the invention and the other 
output of the source for melting the ice being connected from the opposite 
ends of the overhead power transmission line to at least one disconnected 
phase of the overhead power transmission line. 
It is also advisable preferable that a high-voltage network comprise an 
overhead power transmission line with an insulated conductor, said line 
connecting busbars of the transmitting and receiving substations and a 
source for melting the ice, one output being connected during ice melting 
to one end of the insulated conductor and the other output of which being 
grounded. According to the invention, said output of the source for 
melting the ice is connected to one end of the insulated conductor and the 
other end of said insulated conductor is coupled from the opposite ends of 
the overhead power transmission line to at least one disconnected phase of 
the overhead power transmission line. The insulated conductor is grounded 
on the run between the busbars of the transmitting and receiving 
substations. 
It is preferable that a high-voltage network comprise a three-phase source 
as a source for melting the ice, one output of which is connected to one 
end of the insulated conductor. According to the invention, the other 
output of the three-phase source for melting the ice and the insulated 
conductor is grounded, the insulated conductor being grounded between the 
transmitting and receiving substations. 
In a high-voltage network at least one other phase of the power 
transmission line can be connected parallel to the insulated conductor 
during ice melting, according to the invention. 
It is possible that a high-voltage network comprise a three-phase source as 
a source for melting the ice, one output of which is connected to one end 
of the conductor. According to the invention, the insulated conductor and 
the neutral conductor of the three-phase source for melting the ice are 
grounded, the insulated conductor being grounded on the run between the 
transmitting and receiving substations. 
It is also possible that a high-voltage network comprise a three-phase 
source with three outputs as a source for melting the ice. According to 
the invention, all three outputs of the three-phase source for melting the 
ice are connected from one end of different phases of the overhead power 
transmission line, said phases being shorted out at the other end of the 
line. 
There can be employed a high-voltage network comprising at least one 
additional overhead power transmission line leading from the busbars of 
the receiving substation and provided with an insulated conductor, its one 
end being grounded, according to the invention, either the other end of 
the insulated conductor of the additional overhead power transmission line 
is coupled during ice melting to at least one disconnected phase of the 
overhead power transmission line, or one output of the source for melting 
the ice is grounded during ice melting and the other end of the insulated 
conductor of the additional overhead power transmission line is coupled to 
at least one disconnected phase of the overhead power transmission line. 
It is possible to employ a high-voltage network comprising a three-phase 
source as a source for melting the ice, two outputs of which are connected 
during ice melting to the end of the insulated conductor of the overhead 
power transmission line; and at least one additional overhead power 
transmission line leading from the busbars of the receiving substation and 
provided with another insulated conductor, its one end being grounded. 
According to the invention, the third output of the three-phase source for 
melting the ice is grounded and the other end of the insulated conductor 
of the additional overhead power transmission line is coupled during ice 
melting to at least one disconnected phase of the overhead power 
transmission line. 
It is also preferable that a high-voltage network comprise a three-phase 
source, two outputs of which are connected during ice melting to two 
phases of the overhead power transmission line, which are connected to the 
ends of the insulated conductor; and an additional overhead power 
transmission line leading from the busbars of the receiving substation and 
provided with another insulated conductor, its one end being grounded. 
According to the invention, either the other end of the insulated 
conductor of the additional overhead power transmission line is coupled 
during ice melting to at least one disconnected phase of the overhead 
power transmission line and the neutral conductor of the three-phase 
source for melting the ice is grounded or the other end of the insulated 
conductor of the additional overhead power transmission line is coupled 
during ice melting to at least one disconnected phase of the overhead 
power transmission line, the third output of the three-phase source for 
melting the ice being grounded. 
It is expedient that a high-voltage network comprise an additional overhead 
power transmission line leading from the busbars of the receiving 
substation and provided with an insulated conductor. According to the 
invention, the ends of the insulated conductor of the additional overhead 
power transmission line are coupled during ice melting to one disconnected 
phase of this line and the insulated conductor is grounded between the 
receiving substations of the main and additional overhead power 
transmission lines or at the receiving substation of the additional power 
transmission line. 
It is preferable that a high-voltage network comprise a three-phase source 
as a source for melting the ice and an additional line leading from the 
busbars of the main receiving substation and provided with an insulated 
conductor. One end of the disconnected phase of the additional power 
transmission line is, according to the invention, coupled to the 
disconnected phase of the main line and the other end is coupled to the 
end of the insulated conductor at the receiving substation of the 
additional power transmission line, the other end of the insulated 
conductor of said line being connected to two phases of the main line, 
which are shorted out to each other at the receiving substation of the 
main line. 
It is also preferable that a high-voltage network comprise an additional 
power transmission line leading from the busbars of the receiving 
substation and provided with an insulated conductor. According to the 
invention, the insulated conductor of the main line is coupled during ice 
melting to at least one disconnected phase through the additional line and 
its conductor. 
It is expedient that a high-voltage network comprise at least one 
additional line leading from sectionalized busbars of the receiving 
substation of the main line and provided with an insulated conductor. The 
ends of the insulated conductor of the additional power transmission line 
are coupled, according to the invention, during ice melting to one of the 
disconnected phases of said line and the insulated conductor is grounded 
between the receiving substations of the main and additional power 
transmission lines or at the receiving substation of the additional line. 
There can be employed a high-voltage network comprising another additional 
overhead power transmission line leading from the sectionalized busbars of 
the additional substation and provided with an insulated conductor, one 
end of which being grounded, and the other end of which being, according 
to the invention, coupled during ice melting to at least one disconnected 
phase of the additional overhead power transmission line, which leads from 
the busbars of the additional substation. 
It is preferable that, to automate the assembly of the circuitry of a 
high-voltage network for melting the ice, the insulated conductors of the 
network be coupled to a disconnected conductor of the line through a 
series-connected short circuiter and a separator controlled by voltage 
sensors registering appearance and disappearance of a specified voltage. 
The proposed high-voltage network, wherein the ice on insulated conductors 
is melted by means of the above described circuits, permits, according to 
the invention, a considerable reduction of the number of sources for 
melting the icing as compared to existing circuits, a shorter time for 
making a circuit for ice melting and for melting itself, and a reduction 
of conductor insulation or, when the insulation is not changed, a 
considerable increase of the length of heated portions of the conductor by 
raising the voltage of the sources for melting the ice.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1 an embodiment of a high-voltage network comprises a 
supply source 1, transformers 2 and 3 connected by means of switching 
apparatuses 4 and 5 to busbars 6 of the transmitting substation and 
busbars 7 of the receiving substation, an overhead line 8 provided with an 
insulated conductor 9, and a source for melting the ice fed from the low 
voltage busbars (not shown in FIG. 1) of the transmitting substation. 
A converter 10 for converting alternating current into direct current 
(further referred to as the DC source 10 for melting the ice) is used as a 
source for melting the ice. Its one output is connected at the side of the 
transmitting substation to a disconnected phase of the overhead line 8 and 
the other output is connected to the insulated conductor 9. The second end 
of said conductor 9 is coupled to a disconnected phase of the overhead 
line 8 at the receiving substation. 
Referring to FIG. 2, an embodiment similar to that of FIG. 1 employs a 
three-phase transformer 11 with an insulated neutral wire and two 
operating outputs as a source for melting the ice. One of said two outputs 
is coupled at the side of the transmitting substation to a disconnected 
phase of the overhead line 8 and at the other side to the end of the 
insulated conductor 9, the other end of the conductor 9 being coupled to a 
disconnected phase of the overhead line 8 at the receiving substation. 
A high-voltage network of FIG. 3 comprises a DC source 10 for melting the 
ice, one output of which is connected to a ground 12 and the second output 
of which is connected to the beginning of the insulated conductor 9 and a 
disconnected phase of the overhead line 8 joined together. The second end 
of said conductor 9 is coupled to a disconnected phase of the line 8 at 
the receiving substation, the conductor 9 being connected to the ground 12 
between the busbars 6 of the transmitting substation and the busbars 7 of 
the receiving substation. 
The embodiments of the high-voltage networks of FIGS. 4 and 5 are similar 
to that of FIG. 3. The source for melting the ice is in one case a 
three-phase transformer 11 (FIG. 4) with a neutral wire connected to the 
ground 12 and one operating output connected to the beginning of the 
insulated conductor 9 and a disconnected phase of the overhead line 8 
joined together. In the other case, it is also a three-phase transformer 
11 (FIG. 5) with one output connected to the ground 12 and the other 
output connected to the beginning of the insulated conductor 9 and a 
disconnected phase of the overhead line 8 joined together. 
Referring to FIG. 6, a high-voltage network comprises a three-phase 
transformer 11 as a source for melting the ice, one output being coupled 
to a disconnected phase of the overhead line 8, the second output being 
coupled to the end of the insulated conductor 9 grounded between the 
transmitting and receiving substations and coupled by its other end to a 
disconnected phase of the overhead line 8 at the receiving substation, and 
the third output being connected to the ground 12. 
FIGS. 7, 8 and 9 illustrate embodiments of a high-voltage network, wherein 
at least one other phase of the overhead power transmission line 8 is 
connected in parallel with the insulated conductor 9 during ice melting. 
When a DC source 10 for melting the ice (FIG. 7) is employed in a 
high-voltage network, its two outputs are coupled through the busbars 6 to 
the ends of two disconnected phases of the line 8, the two other ends of 
the disconnected phases of the line 8 being joined together and connected 
to the end of the insulated conductor 9 at the receiving substation. The 
beginning of said conductor 9 is coupled to a disconnected phase at the 
transmitting substation. 
When the three-phase transformer 11 (FIG. 8) for melting the ice with an 
insulated neutral conductor is employed, its two outputs are connected to 
the busbars 6 of the transmitting substation, the circuit being similar to 
that of FIG. 7 in all other respects. 
FIG. 9 illustrates a high-voltage network, wherein a disconnected phase of 
the line 8 is coupled in parallel with one more phase of the line 8 
besides being coupled to the insulated conductor 9. 
A high-voltage network of FIG. 10 comprises a three-phase transformer 11 
for melting the ice, one output of which is coupled to one end of the 
insulated conductor 9, another output of which is coupled to a 
disconnected phase of the overhead line 8, and the neutral conductor of 
which being connected to the ground 12. The insulated conductor 9 is 
grounded between the transmitting and receiving substations. 
FIG. 11 illustrates a high-voltage network wherein all three outputs of the 
three-phase source 11 for melting the ice are connected to different 
phases of the overhead line 8 at one end of said line 8, the other ends 
being shorted out and the insulated conductor 9 being connected in 
parallel with any phase of the line 8. 
Referring to FIGS. 12-20, embodiments of a high-voltage network comprise an 
additional overhead power transmission line leading from the busbars 7 of 
the receiving substation of the overhead line 8 and provided with an 
insulated conductor 13, which one of which is connected to the ground 12 
and the other end of which is coupled during ice melting to at least one 
disconnected phase of the main overhead power transmission line 8. 
Referring to FIG. 12, an embodiment of a high-voltage network has an 
additional overhead line provided with the insulated conductor 13, the DC 
source 10 for melting the ice and the insulated conductor 9 of the main 
overhead line 8 being connected during ice melting in a circuit similar to 
that of FIG. 3. 
FIG. 13 illustrates an embodiment of a high-voltage network with an 
additional overhead line provided with the insulated conductor 13, wherein 
the three-phase transformer 11 for melting the ice and the insulated 
conductor 9 of the main overhead line 8 are connected during ice melting 
as in the circuit of FIG. 4. 
FIG. 14 illustrates an embodiment of a high-voltage network with an 
additional overhead line provided with the insulated conductor 13, wherein 
the three-phase transformer 11 for melting the ice and the insulated 
conductor 9 of the main overhead line 8 are connected during ice melting 
as in the circuit of FIG. 5. 
FIG. 15 illustrates an embodiment of a high-voltage network with an 
additional overhead line provided with the insulated conductor 13, wherein 
the three-phase transformer 11 and the insulated conductor 9 of the main 
overhead line 8 are connected during ice melting as in the circuit of FIG. 
6. 
FIG. 16 illustrates an embodiment of a high-voltage network with an 
additional overhead line provided with the insulated conductor 13, wherein 
the three-phase transformer 11 for melting the ice and the insulated 
conductor 9 of the main overhead line 8 are connected during ice melting 
in a circuit similar to that of FIG. 10. 
FIG. 17 illustrates an embodiment of a high-voltage network with an 
additional overhead line provided with the insulated conductor 13, wherein 
the DC source 10 for melting the ice and the insulated conductor 9 of the 
main overhead line 8 are connected during ice melting as in a circuit 
shown in FIG. 1, but one output of the source 10 being connected to the 
ground 12. 
FIG. 18 illustrates an embodiment of a high-voltage network with an 
additional overhead line provided with the insulated conductor 13, wherein 
the three-phase transformer 11 for melting the ice and the insulated 
conductor 9 are connected during ice melting in a circuit similar to that 
of FIG. 2, but one output of the transformer 11 being connected to the 
ground 12. 
FIGS. 19 and 20 illustrate embodiments of a high-voltage network with an 
additional overhead line provided with the insulated conductor 13, wherein 
the three-phase transformer 11 for melting the ice and the insulated 
conductor 9 of the main line 8 are connected during ice melting in a 
circuit similar to that of FIG. 2, but the grounding circuit 12 being in 
one case connected to one of the outputs of the transformer 11 (FIG. 19) 
and in the other case to the neutral conductor of said transformer 11 
(FIG. 20). 
Referring to FIGS. 21-38, embodiments of a high-voltage network comprise at 
least one additional overhead power transmission line (one line 15 in the 
described examples) leading from the busbars 7 of the receiving substation 
of the main overhead power transmission line 8 and provided with an 
insulated conductor 16, whose ends are coupled during ice melting to one 
disconnected phase of the additional line 15. The insulated conductor 16 
is connected to the ground 12 between the receiving substations of the 
main line 8 and the additional line 15 (FIGS. 21-25, 31-34) or at the 
receiving substation of the additional power transmission line 15 (FIGS. 
26-30, 35-38). 
Referring to FIG. 21 the DC source for melting the ice and the insulated 
conductor 9 of the main overhead power transmission line 8 are connected 
during ice melting in a circuit similar to that of FIG. 3. 
Referring to FIGS. 22, 23, 24 and 25 the three-phase transformer 11 for 
melting the ice and the insulated conductor 9 of the main overhead power 
transmission line 8 are connected during ice melting as in the circuits 
shown in FIGS. 4, 5, 6 and 10, respectively. 
Referring to FIGS. 27, 28, 29, 30, the three-phase transformer 11 for 
melting the ice and the insulated conductor 9 of the main overhead power 
transmission line 8 are connected during ice melting as in the respective 
circuits of FIGS. 4, 5, 6 and 10. 
Referring to FIG. 31, the DC source 10 for melting the ice and the 
insulated conductor 9 of the main overhead line 8 are connected during ice 
melting as in the circuit of FIG. 17. 
Referring to FIGS. 32, 33, 34, the three-phase transformer 11 for melting 
the ice and the insulated conductor 9 of the main overhead line 8 are 
connected during the ice melting in circuits corresponding respectively to 
FIGS. 18, 16, 19, the insulated conductor 16 of the additional overhead 
power transmission line 15 shown in FIG. 34 being coupled by its ends to 
two disconnected phases of the additional line 15. 
Referring to FIGS. 35, 36, 37, 38, the DC source 10 and the three-phase 
transformer 11 for melting the ice and the insulated conductor 9 of the 
main overhead line 8 are connected during ice melting as in the circuits 
of FIGS. 17, 18, 16, 19 respectively. 
The high-voltage network of FIG. 39 comprises the three-phase transformer 
11 for melting the ice, the main overhead power transmission line 8 with 
the insulated conductor 9 and the additional power transmission line 15 
with the insulated conductor 16. A disconnected phase of the additional 
line 15 has one end coupled during ice melting to a disconnected phase of 
the main power transmission line 8 and the other end coupled to the end of 
the insulated conductor 16 at the receiving substation of the additional 
power transmission line 15. The other end of the insulated conductor 16 of 
said line 15 is connected to two phases of the main line 8, which are 
shorted out at the receiving substation of the main power transmission 
line 8. 
Referring to FIG. 40, a high-voltage network comprises one additional power 
transmission line 15 leading from the busbars 7 of the receiving 
substation of the main power transmission line 8 and provided with the 
insulated conductor 16. The insulated conductor 9 of the main power 
transmission line 8 is coupled during ice melting to at least one 
disconnected phase through the additional line 15 and its insulated 
conductor 16. 
FIGS. 41-49 illustrate embodiments of a high-voltage network comprising 
another overhead power transmission line leading from sectionalized 
busbars 14 of the receiving substation of the additional line 15 and 
provided with an insulated conductor 17, one end of which is connected to 
the ground 12 and the other end of which is coupled during ice melting to 
at least one disconnected phase of the other additional line leading from 
the sectionalized busbars 14 of the receiving substation. 
Referring to FIG. 41, the DC source 10 for melting the ice and the 
insulated conductors 9 and 16 are connected during ice melting as in the 
circuit of FIG. 21. 
Referring to FIGS. 42, 43, 44, the three-phase transformer 11 for melting 
the ice and the insulated conductors 9 and 16 are connected during ice 
melting as in the circuits of FIGS. 22, 24 and 25 respectively. 
The embodiment of FIG. 45 uses the three-phase transformer 11 with the 
neutral conductor connected to the ground 12 and the three operating 
outputs connected to the busbars 6 of the transmitting substation of the 
main power transmission line 8, two busbars 7 of the receiving 
substations, which are connected to the ends of the insulated conductors 9 
and 16, being shorted out. 
Referring to FIGS. 46, 47, 48 and 49, the DC source 10 for melting the ice, 
the three-phase transformer 11 and the insulated conductors 9 and 16 are 
connected during ice melting as in circuits similar to those of FIGS. 35, 
36, 33 and 34, respectively. 
To effect automatic connection of the circuit for melting the ice, a 
circuit shown in FIG. 50 is used in the proposed high-voltage network, 
wherein insulated conductors 18 of the overhead line are connected to a 
sectionalized busbar 19 to melt the ice on said conductors 18 through a 
series-connected short-circuiter 20 and a separator 21. 
The sectionalized busbar 19 is connected to the sectionalized busbars 7 of 
the transmitting substation through a disconnector 22. The sectionalized 
busbars 7 are coupled to the conductors of a disconnected power 
transmission line both during ice melting and in normal operation of the 
network. 
To register the presence or absence of a specified voltage the busbar 19 is 
joined to a voltage sensor 23 which controls the short circuiters 20 and 
separators 21. 
The insulated conductor 9 is heated in the high-voltage network of FIG. 1 
by the passage of current in the following circuit: one output of the DC 
source 10 -- the beginning of the heated conductor 9 -- the conductor 9 -- 
the end of the conductor 9 coupled to a disconnected phase of the line 8 
at the receiving substation -- conductor of the disconnected phase of the 
line 8 -- the phase of the sectionalized busbars 6 of the source 10. In 
this case the degree of insulation of the conductor 9, as compared to that 
used in the known method of melting the ice on conductors by the circuit 
"source for melting the ice - conductor - ground", is reduced by one half, 
because the total voltage of the source 10 is applied to two insulators 
(not shown) which are connected in series through the ground at the 
beginning and at the end of the conductor. 
The conductor 9 is heated in the circuit of FIG. 2 in a manner similar to 
that of FIG. 1, the source for melting the ice being the three-phase 
transformer 11. 
In the high-voltage network which comprises the overhead line 8, provided 
with the insulated conductor and connecting the busbars 6 and 7 of the 
transmitting and receiving substations, and a source for melting the ice, 
the conductor with a lower insulation level can be heated with the 
circuits of FIGS. 3, 4 and 5. 
The portion of the conductor 9 is heated by the circuits of FIGS. 3, 4, 5 
by means of passing the current as follows: the output of the source 10 or 
the three-phase transformer 11, which is coupled to a disconnected phase 
of the sectionalized busbars 6 -- the disconnected phase of the line 8 -- 
the beginning of the portion of the conductor 9 connected to a phase of 
the line 8 at the transmitting substation 13 a portion of the conductor 9 
-- the ground 12 of the conductor 9 -- the ground circuit of the supply 
substation -- the second output of the source 10 or the three-phase 
transformer 11. 
The portion of the conductor 9 between the ground 12 and the busbars 7 of 
the receiving substation is heated similarly to the portion of said 
conductor 9 between the transmitting substation and the ground 12 of the 
conductor 9. The voltage of the source for melting the ice is applied 
between the ends of the conductor 9 and the ground 12, that is the total 
voltage for the DC source 10 according to the circuit of FIG. 3, the phase 
voltage according to the circuit of FIG. 4 and the line voltage according 
to the circuit of FIG. 5. With the known methods for melting the ice on 
the conductors 9, the degree of insulation of conductors and, 
respectively, the voltage of the ice melting source should be twice that 
of the circuits of FIGS. 3, 4 and 5 connected in accordance with the 
invention. 
The conductor 9 is heated according to the circuit of FIG. 6 by passing the 
current as follows: 
(a) for the portion of the conductor 9 between the transmitting substation 
and the ground 12 of the conductor 9: one output of a phase of the source 
11 -- of the portion of the conductor 9 -- the ground 12 of the conductor 
9 -- the ground 12 of the transmitting substation -- the second output of 
the phase of the source 11; and 
(b) for the portion of the conductor 9 between the receiving substation and 
the ground 12 of the conductor 9: the third output of a phase of the 
transformer 11 -- a phase of sectionalized busbars 6 -- a disconnected 
phase of the line 8 -- the portion of the conductor 9 -- the ground 12 of 
the conductor 9 -- the ground 12 of the transmitting substation -- the 
second output of the phase of the transformer 11. The current flows along 
circuits by the action of the line voltage of the transformer 11. 
The conductor 9 is heated by the circuits of FIGS. 7, 8, 9, 11 by passing 
the current as follows: one output of the source 10 or the transformer 11 
-- a phase of the busbars 6 -- the conductor 9 -- a phase of the line 8 -- 
the second output of the source 10 or the transformer 11. Such method of 
melting the ice can be employed concurrently with ice melting on the 
conductors of the line 8 effected in a "conductor-conductor" circuit 
(FIGS. 7, 8) or a "conductor-two conductors" circuit (FIG. 9) or a "three 
conductors" circuit (FIG. 11). The current flows along the conductor 9 by 
the action of the voltage drop in the conductor of the line 8. 
The conductor 9 is heated by the circuit of FIG. 10 similarly to the 
circuit of FIG. 6, wherein the three-phase transformer 11 with a grounded 
neutral conductor is used as a source for melting the ice. The current 
passes by the action of the phase voltage of the transformer 11 along the 
following circuit: a phase of the source 11 -- a portion of the conductor 
9 -- the ground 12 of the conductor 9 -- the ground 12 of the neutral 
conductor of the source 11 -- and a phase of the source 11 -- a 
disconnected phase of the line 8 -- a portion of the conductor 9 -- the 
ground 12 of the conductor 9 -- the ground 12 of the neutral conductor of 
the source 11. 
The conductor 13 is heated by the circuits of FIGS. 12-20 by passing the 
current along the following circuit: one output of the source 10 or the 
three-phase transformer 11 -- a phase of the busbars 6 -- a disconnected 
phase of the line 8 -- the conductor 13 of the additional line leading 
from the busbars 7 of the receiving substation -- the ground 12 of the 
conductor 13 -- the grounding 12 of the source 10 or the transformer 11. 
The conductors 13 of the lines leading from the receiving substation are 
heated along the circuit where the ground is used as a connecting return 
conductor. In this connection there is provided a tie of the potential of 
the source 10 for melting the ice to the circuit of the ground 12. When 
the transformer 11 with an insulated neutral conductor is used as a source 
for melting the ice, the tie of the potential is effected by connecting 
one of its phases to the ground 12. 
In a high-voltage network comprising, apart from the transmitting and 
receiving substations with an overhead line therebetween, one more 
additional line with an additional receiving substation, the conductor of 
this additional line can be heated by the circuits shown in FIGS. 21-33, 
as well as the circuits shown in FIGS. 39 and 40. The conductors of the 
main line and the additional line leading from the busbars of the 
receiving substation can be heated together with the conductors of the 
line between the main and additional receiving substations. 
Portions of the conductor 16 grounded on the conductor of the additional 
line 15 are heated by the circuits of FIGS. 21-25, 31-33 by passing the 
current as follows: 
(a) for the portions of the conductor 16 between the busbars 7 of the 
receiving substation and the ground 12 of the conductor 16: one output of 
the source 10 for melting the icing or the transformer 11 -- a 
disconnected phase of the main line 8 -- a phase of the busbars 7 of the 
receiving substation -- a portion of the conductor 16 -- the ground 12 of 
the conductor 16 -- the ground 12 of the source 10 or the transformer 11 
for ice melting; and 
(b) for the portion of the conductor 16 between the busbars 14 of the 
additional line 15 and the ground 12 of the conductor 16: one output of 
the source 10 for melting the icing or the transformer 11 -- a 
disconnected phase of the main line 8 -- a phase of the busbars 7 -- a 
disconnected phase of the additional line 16 -- a portion of the conductor 
16 -- the ground 12 of the conductor 16 -- the grounding 12 of the source 
10 or the transformer 11. 
The conductor 16 of the additional line 15 is heated by circuit shown in 
FIGS. 34, 38 by passing the current under the effect of the line voltage 
similarly to the circuit shown in FIGS. 23 and 29, respectively. 
The conductor 16 grounded at the receiving substation of the additional 
line 15 is heated by the circuits of FIGS. 26-30, 35-38 by passing the 
current through the conductor 16 under the effect of the voltage drop at 
the disconnected phase of the line 15. This method of melting the ice on 
the conductors 16 is convenient to employ when concurrently melting the 
ice on the disconnected conductors of the lines 8 and 15 according to the 
circuit "conductor-ground". 
The conductor 16 of the additional line 15 is heated by the circuit shown 
in FIG. 39 by passing the current under the effect of the line voltage of 
the transformer 11 as follows: a phase of the transformer 11 -- 
disconnected phases of the lines 8 and 15, which are connected is series 
on the busbars 7 of the receiving substation -- the conductor 16 of the 
line 15 -- the busbars 7 of the receiving substation -- phases of the line 
8 shorted out at the receiving substation -- outputs of the transformer 
11. 
The conductor 16 of the additional line 15 is heated according to the 
circuit shown in FIG. 40 by passing the current under the effect of the 
full voltage of the source 10 for melting the ice as follows: the output 
of the source 10 -- a disconnected phase of the line 8 -- a phase of the 
busbars 7 -- a phase of the line 15 -- the conductors 16 -- the conductor 
9 -- another output of the source 10. 
The conductor 17 of the additional line leading from the busbars 14 of the 
receiving substation is heated by to the circuits shown in FIGS. 41-49 
similarly to the circuits shown in FIGS. 12-20, respectively. 
It is important that the conductors of the network are automatically 
connected to a disconnected conductor of the line if there is no duty 
personnel at a substation. 
Automatic connection of the conductor to the busbars to melt the ice 
thereon is done as follows: the disconnector 22 (FIG. 50) is switched on 
in advance of the ice season. When the voltage for melting the icing, 
which is different from the operational voltage, is supplied, the sensor 
23 feeds a pulse to switch on the short circuiters 20; normally the 
separators 21 are closed. When the process of melting is completed, the 
voltage is no longer supplied and the sensor 23 gives the command to 
switch off the separators 21. Reestablishment of the circuit is done 
manually or by remote control. 
The sensor 23 does not respond to the value of the operational voltage 
since the voltage for melting is lower. 
This invention permits melting of ice on conductors of power transmission 
lines leading from distribution substations by means of one source. 
Besides, considerable reduction of the degree of insulation of the 
conductor is achieved by dividing the conductor into a number of portions 
and supplying each such portion with a voltage sufficient for heating the 
conductor by means of disconnected conductors of the power transmission 
line. 
The value of the voltage required for melting the ice on the conductor and, 
consequently, the degree of the conductor-insulation are reduced in direct 
proportion to the ratio between the length of a separated portion of the 
conductor and its total length.