Prysmian
Prysmian

Hungarian Version


Table of Contents

• Terms & Conditions
• Privacy policy
• Current Carrying Capacity and Correction Factors
• Base Conditions
• Energy Conscious Solution
• Example of Economic / Ecologic Calculation

A) CURRENT CARRYING CAPACITY and CORRECTION FACTORS

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The CableApp uses the correction factors as defined in the Table B.52.1 of IEC 60364-5-52. This allows the user to tailor a circuit rating for their given prescribed installation. These correction factors cover the following parameters: ambient temperature (air, and ground where appropriate), soil resistivity, depth, proximity of multiple circuits for ladder, tray, direct in ground and in ducts in the ground.

B) BASE CONDITIONS

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The published current ratings in IEC / HD 60364-5-52 are based on the following conditions:

Parameter Condition
Ambient Air temperature 30°C
Ambient Ground temperature 20°C
Base installation depth (cables installed in the ground)    0.8m
Base soil resistivity (cables laid in the ground) 2.5 K.m/W


The published current ratings in IEC 60502-2 are based on the following conditions:

Parameter Condition
Ambient Air temperature 30°C
Ambient Ground temperature 20°C
Base installation depth (cables installed in the ground)    0.8m
Base soil resistivity (cables laid in the ground) 1.5 K.m/W


The published current ratings in HD 620 S2 are based on the following conditions:

Parameter Condition
Ambient Air temperature 30°C
Ambient Ground temperature 20°C
Base installation depth (cables installed in the ground)    0.7m
Base soil resistivity (cables laid in the ground) 1.0 K.m/W

Energy Conscious Solution

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The following information provides guidance in energy efficiency, and the calculation method used to provide the Energy Conscious Solution in the CableApp
The calculation requires the end user to define some of the parameters used in the calculation, within the "Settings" menu of the CableApp
The potential savings should be considered as guidance only
According to Joules Law, whenever a conductor carries current, it will generate heat (thermal energy)
Thermal energy of a cable corresponds to the following general formulae:

EP = n/c · R · L · I² · t/1000

Where:

EP: energy generated (lost on the line) [kWh]
n: number of loaded conductors (2 for single-phase/dc or 3 for three-phase)
c: number of cables per phase
R: conductor resistance [Ω / km]
L: cable length [km]
I: line current [A]
t: time [h]

If the cross-sectional area (S) of a cable is increased, there will be a corresponding reduction in the resistance (R). When carrying the same current I, there will be a reduction in the energy loss (EP). This energy saving can be quantified both as a cost saving in electricity bills and a reduction in CO2 emissions.
The cable itself will be more expensive because it will have a higher cross-sectional area (S) but the installer will benefit from the following:
- Lower running costs, reduced energy bills.
- Reduced CO2 emissions, therefore an environmentally better proposition.
- Extended design life for the cable because it is operating at a lower temperature.

Standard design life is based on the cable being at its maximum load (maximum operating temperature) for every hour of that defined life in years.
- Improved short circuit capability - larger cross-sectional areas will carry higher currents in a fault condition.
- Potential to uprate the cable to carry higher loads in the future.

As a rule, cables do not carry the same current (I) continuously. For this reason, it is advisable to consider the mean square value of the current over time or at least to make an estimate.
The CableApp will offer by default the average usage of load (I ') equal to 75% of I, but other values can be selected or defined by the user in the "Settings" of the CableApp:

100% I
40% I (residential)
60% I (public place)
75% I (industrial)
Other %


Thus, the energy saved (EA) by installing conductors of lower resistance (R2) than (R1) will be:

EA = n/c · (R1-R2) · L · (%U · I)² · t/1000

Having calculated the saved energy, the economic savings can be calculated (A£) and the savings in CO2 emissions since we have defined the electricity tariffs (Energy Price) in HUF/kWh (in the "settings") and the approximate values of CO2 emissions (ACO2) kg per kWh generated taking account of the country’s energy mix is defined by the CableApp (note, this value cannot be modified by the user). Entering the value of the electricity rate and the value of CO2 emissions per kWh will therefore give the savings achieved by installing cross-section conductors with a larger section.

Energy Price: 37.55 HUF / kWh (is defined by the user in "Settings")
CO2 Emissions: 0.40 kg CO2 / kWh (HU default value, not possible to edit)

Example of Economic / Ecologic Calculation

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Let’s assume we want to carry out an economic and ecological calculation as follows:

System - three-phase; 130 m; 268A (dummy data)
CableApp Proposed Technical Size - 95mm² copper conductor

To calculate the savings, we must consider increasing the cross-sectional area from 95mm² to the next largest standard cross-section, which is 120mm².

Resistance Low voltage
Conductor material Cross section Resistance
Al 2,5 14,538
Al 4 8,903
Al 6 5,539
Al 10 3,7
Al 16 2,295
Al 25 1,442
Al 35 1,043
Al 50 0,77
Al 70 0,533
Al 95 0,385
Al 120 0,305
Al 150 0,249
Al 185 0,198
Al 240 0,152
Al 300 0,122
Al 400 0,096
Al 500 0,076
Al 630 0,061
Al 800 0,05
Al 1000 0,042
Cu 1 21,657
Cu 1,5 14,478
Cu 2,5 8,866
Cu 4 5,516
Cu 6 3,685
Cu 10 2,19
Cu 16 1,376
Cu 25 0,87
Cu 35 0,627
Cu 50 0,464
Cu 70 0,322
Cu 95 0,232
Cu 120 0,185
Cu 150 0,151
Cu 185 0,121
Cu 240 0,094
Cu 300 0,076
Cu 400 0,062
Cu 500 0,051
Cu 630 0,042


Resistance Medium voltage
Conductor material Cross section Resistance
Al 50 0,822
Al 70 0,568
Al 95 0,411
Al 120 0,325
Al 150 0,265
Al 185 0,211
Al 240 0,161
Al 300 0,129
Al 400 0,101
Al 500 0,08
Al 630 0,063
Al 800 0,051
Al 1000 0,042
Cu 50 0,494
Cu 70 0,342
Cu 95 0,247
Cu 120 0,196
Cu 150 0,159
Cu 185 0,128
Cu 240 0,098
Cu 300 0,079
Cu 400 0,063
Cu 500 0,051
Cu 630 0,042


Reference is made in the background of the App to the electrical resistance table (above), calculated at a given average operating temperature. The R value for the next size is selected, in this case 120mm².

For the simplicity of the calculation, both conductors are assumed to operate at the same temperature. The resistance for the larger conductor will be lower than given in the table when carrying the same load, because the larger conductor will operate at a lower temperature. The subsequent savings will be a conservative estimate.

If the calculation is undertaken for an annual usage, then the time (t) will be 365days • 24h = 8760 h.

We will assume the average usage is 75% (default value in the App, but this can be changed in the “settings” menu)

Now we can calculate the energy that can be saved in a year using 120 mm² instead of 95 mm².

EA  = (n/c • (R150 - R185) • L • (%U • I')² • t) / 1,000
      = (3/1 • (0.231 - 0.185) • 0.13 • (0.75 • 268)² • 8760) / 1000
      = 6480 kWh

We have defined the chosen installation with a tariff rate for electrical energy of 37.55 HUF / kWh (remember the user should define their Tariff in the "settings").

The CableApp uses a default value for CO2 emission equal to 0.40 kg CO2 / kWh.

Energy Price 37.55 HUF / kWh (value can be changed in "settings" menu)

CO2 emissions 0.40 kg CO2 / kWh (value proposed by default)

AHUF = 6480 kWh • 37.55 HUF / kWh = 243324 HUF

ACO2 = 6480 kWh • 0.40 kg CO2 / kWh = 2592 kg CO2
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