- Conductor Resistance Test Definition: The conductor resistance test measures the DC resistance of copper or aluminum conductors to determine how easily they allow current flow.
- Importance of Resistance: Higher resistance in a conductor results in less current flow, which is crucial for efficient power transmission.
- Test Equipment: The test uses a Kelvin Double Bridge or Wheatstone Bridge to measure resistance accurately.
- Testing Procedure: Involves connecting the conductor to a resistance measuring bridge, measuring resistance, and adjusting for temperature and length.
- Conclusion: The test results indicate if the conductor meets specified resistance standards, ensuring reliability in electrical power cables.
This test measures the DC resistance of copper or aluminum conductors. The resistance shows how easily current flows through a conductor. Higher resistance means less current flow. Factors like conductor size, construction, temperature, and resistivity affect resistance. It is usually expressed in ohms per kilometer.
The test uses either a Kelvin Double Bridge, with 0.2% accuracy, or a Wheatstone Bridge, with 0.5% accuracy.
Test specimen is selected as indicated below.
- All solid circular conductor Drum length of 1 m
- All stranded or sector shaped solid conductors up to and including 25 mm2 size Drum length of 5 m
- All stranded or sector shaped solid conductors greater than 25 mm2 size Drum length of 10 m
Note – The length of the test specimen is the length which lies between the potential terminals.
Procedure of Conductor Resistance Test
Connect the specimen to the resistance measuring bridge and make sure that proper considerations are taken into account about the contact resistance.
Measure the resistance and note down the temperature.
Measured resistance is converted to the standard temperature and length.
Observation and Report
| Sample no | Nominal conductor size in mm2 | Length (m) | Material Al/Cu | Class of conductor | Temperature oC | Observed Resistance | Specified Resistance |
| – | – | – | – | – | – | – | – |
| – | – | – | – | – | – | – | – |
| – | – | – | – | – | – | – | – |
Calculation
Observed Resistance at a particular temperature,
Where,
Rt = Observed Resistance
K = Temperature correction factor
L = Length of specimen in m.
Conclusion: The sample either meets or does not meet the specified requirements.
