Resistance Corrected to 20°C
Conductor resistance values are normally expressed as:
Ω/km at 20°C
The measured value is corrected for:
Measured Resistance
The actual DC resistance recorded by the test instrument.
Sample Length
The result is converted to resistance per kilometre.
Conductor Temperature
A temperature correction factor is applied so that results obtained at different laboratory temperatures can be compared at the standard reference temperature of 20°C.
The final corrected resistance is then compared with the maximum value permitted by the applicable conductor standard.
Conductor Requirements for H1Z2Z2-K Solar Cable
For H1Z2Z2-K cable according to EN 50618, the conductor is:
Tinned Copper
The conductor wires are copper with a continuous tin coating.
Class 5 Flexible Conductor
The conductor construction complies with the requirements for Class 5 conductors specified in EN / IEC 60228.
Resistance at 20°C
The conductor resistance must not exceed the maximum value specified in EN 60228 for the corresponding metal-coated Class 5 copper conductor.
EN 50618 specifies conductor resistance testing according to EN 50395 Clause 5, which in turn refers to the conductor resistance measurement procedure of EN 60228.
Conductor Resistance for IEC 62930 PV Cable
IEC 62930 also requires photovoltaic cable conductors to be copper with tin-coated wires.
For cables directly connected to PV modules, Class 5 conductors according to IEC 60228 are required. Class 2 conductors may also be used for certain fixed installations that are not directly connected to PV modules.
The measured conductor resistance is evaluated against the applicable maximum resistance specified in IEC 60228.
Pass / Fail Evaluation
PASS
The conductor resistance corrected to 20°C does not exceed the maximum resistance permitted for the specified conductor size, class and construction.
FAIL
A corrected resistance above the applicable maximum limit indicates that the conductor does not meet the required electrical resistance specification.
An excessive resistance value may be associated with factors such as insufficient conductive cross-section, conductor construction variation, poor strand quality or material-related issues.
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