Explanatory note on MRV methodology “Installation of energy-saving transmission
lines in the Mongolian Grid”

1. Eligibility criteria
In Mongolia, Aluminum Conductors, Coated-Steel Reinforced (ACSR) are commonlyused for overhead transmission lines. Their specifications are determined as per
Mongolian standard MNS 5870: 2008 shown in Table 1.
Table 1 Characteristics of ACSR used in Mongolia
Type of ACSR

−ACSR
240/32mm2

ACSR
300/39mm2

ACSR
400/51mm2

Aluminum wire
Zinc coated steel wire
No. of wire
Aluminumwire
DiameterConstruction
Zinc coated No. of wire
steel wire
DiameterAluminum wire
No. of layer
Zinc coated steel wire
Aluminum wireCalculated
cross-sectional area Zinc coated steel wire
Outer diameter of conductor
Diameter of steel coreDirect current resistance at 20deg.C
Minimum tensile strength
Aluminum wire
Nominal Weight
Zinc coated steel wire
Total

mm2

240
32
24
3.60
7
2.40
2
1244
31.7
21.6
7.2
0.118275,050
673
248
921

300
39
24
4.00
72.65
21301
38.6
24.0
8.0
0.095890,574
830
302
1,132

400
51
54
3.05
7
3.05
31394
51.1
27.5
9.2
0.0733
120,481
1,090
400
1,490

Cross-sectional
area

Nos.
mm
Nos.
mm
layer
mm2mm
mm
Ω/km
Nkg/kmThe conductors shown above are used in major high voltage transmission lines (110kV andabove) in Mongolia, being selected to meet required transmission capacity. Mongolia has acommon design for steel lattice towers, and standard ACSR are installed on such steel lattice
towers. Therefore, Low Electrical Power Loss Aluminum Conductors, Aluminum-Clad Steel
Reinforced (LL-ASCR/SA) must be designed to have same mechanical characteristics (outerdiameter, nominal weight and minimum tensile strength) as conventional ACSR used inMongolia, to be able to be installed on Mongolian standard steel lattice towers without any
modification and reinforcement of steel tower members and/or tower foundation.
Furthermore, to ensure a high standard of technology to be implemented, another criterion isintroduced whereby electrical resistance (as defined as direct current resistance) ofLL-ACSR/SA should be at least 10% lower than that of conventional ACSR that are currently
operating in Mongolia. As a result, the eligibility criteria of the project transmission
conductors are established as shown in Table 2:1

Table 2 Eligibility criteria of project transmission conductors
ACSR
ACSR
ACSR
Type of conductor (ACSR)
22240/32mm
300/39mm
400/51mm2
Equivalent toTypeofcorresponding
Equivalent toEquivalent to
LL-ACSR/SA
LL-ACSR/SA
energy-saving
conductor
LL-ACSR/SA
445/36mm2
337/27mm2(LL-ACSR/SA)
279/20mm2≦ 21.6≦ 24.0≦ 27.5Outer diameter of conductor
mmDirect current resistance≦ 0.1063≦ 0.0862≦ 0.0659
Ω/km
at 20deg.C
Tensile strengthN≧ 75,050≧ 90,574≧ 120,481

Nominal weightkg/km≦ 921≦ 1,132≦ 1,490

2. Establishment of reference emissions: rationale of algorithm
As described above, energy-saving conductors, by possessing the same mechanicalcharacteristics (outer diameter, nominal weight and minimum tensile strength) as
conventional ACSR currently used, can substitute them while using the steel lattice
towers of the same design (positional relation of installed conductors can be retained).
Therefore, when calculating transmission loss, the only factor that needs to be consideredis the resistance of the conductors themselves; there is no need to consider the difference
in reactance and admittance caused by different diameter and distance between theconductors.
From the above, it follows that the transmission loss of currently used conductors iscalculated as a product of transmission loss of energy-saving conductors (which ismonitored) and ratio of transmission loss between current (reference) and energy-saving
conductors, as follows:

LOSSRF,L, y = LOSSPJ,L, y ´

RacRF,LRacPJ,L

whereLOSSRF,L,y=Reference transmission loss of transmission line L in the year y [MWh/y]

LOSS PJ,L,y=Project transmission loss of transmission line L in the year y [MWh/y]

Rac RF,L=Rac PJ,L=Alternative current resistance of transmission line L using currently usedtransmission conductors.[Ω/km]
Alternative current resistance of transmission line L using energy-saving
conductors. [Ω/km]

Resistance of transmission lines is positively correlated with conductor temperature,
which in turn is affected by the ambient conditions (temperature, wind velocity and2

solar radiation). For all type of conductors, the relationship between conductor
temperature t and direct current resistance Rdc can be denoted as follows

Rdc(t) = Rdc(20deg.C) *(1+0.00403*(t-20))
Where the constant-mass temperature coefficient at 20deg.C 0.00403 is derived from thestandard IEC 889-1987 (Hard-drawn aluminum wire for overhead line conductors).
Generally with ASCR as well as LL-ASCR/SA, alternate current resistance is more thandirect current resistance due to “skin effect” derived from increased impedance in the insideof the conductor, and core loss (iron loss) and eddy current loss. This increase is calculatedby the formula recommended by Conseil International des Grands Réseaux Électriques(CIGRE) based on the assumption that, with ACSR, electrical input is identical when theaverage temperature is identical, as follows:
Ratio of direct and alternate current resistanceRac= 1.0123 + 2.36 ´10 -5 * Iac
Rdc

in three-layer aluminum conductor
Ratio of direct and alternate current resistanceRac= 1.0045 + 0.09 ´ 10 -6 * Iac
Rdc

in two-layer aluminum conductor

WhereRac= alternate current resistance (Ω)

Rdc= direct current resistance (Ω)

Since LL-ACSR/SA are designed two-layered aluminum and some of the ACSR currently in
use are three-layered aluminum, the ratio of alternative current resistance between
LL-ACSR/SA and ACSR is larger than the ratio of direct current resistance. Furthermore,
conductor temperature is bound to be higher than ambient temperature due to power flow oftransmission line, and conductor temperature rise and electrical resistance of conductor arepositively correlated. Therefore, there is a further element of conservativeness by assumingthat conductor temperature is identical to ambient temperature. These multiple levels ofconservative assumptions ensures that the methodology achieves net reductions, which isprobably about 6-8% of emission reductions calculated as per the methodology.

3. Establishment of reference emissions: data for calculating reference emissions.
3As mentioned before, direct current resistance for the purpose of calculating reference
emissions will be based on the Mongolian standard MNS 5870: 2008. It is possible that thisstandard is overachieved at present, resulting in deployment of conductors whose resistanceis lower than what is prescribed in the standard. There are two possibilities for this to happen,
namely a) the diameter of each strand is larger, and b) the conductivity of material is higher.
The latter is deemed unlikely to happen since the conductive material is made from purealuminum and there is very little room to vary conductance: therefore it is assumed that thediameter of each strand for reference conductor is 1% larger than its specification, which is
the maximum allowable tolerance of major international standard such as IEC, etc., resulting
in 2% reduction in resistance since resistance is inversely proportional to the cross-sectional
area. Therefore, for the purpose of calculating reference emissions, the direct current
resistance as prescribed in MNS 5870: 2008 is discounted by 2% to yield as shown in Table 3:

Table 3 Figures for RdcRF,LType of energy-saving
conductor(LL-ACSR/SA)
Type of corresponding
conductor (ACSR)
RdcRF,L (Direct current
resistance at 20degC)−Ω/km

Equivalent to
LL-ACSR/SA
279/20mm2
ACSR
240/32 mm2Equivalent to
LL-ACSR/SA
337/27mm2
ACSR
300/39 mm2Equivalent to
LL-ACSR/SA
445/36mm2
ACSR
400/51 mm2

0.11580.09390.07184