IEEE Std 1893-2015 pdf download – IEEE Guide for the Measurement of DC Transmission Line and Earth Electrode Line Parameters.
4.2 Contents of transmission line parameter measurement Measurement of transmission line parameters consists of the following: a) DC resistance measuring b) Impedance frequency characteristic measuring 4.3 General considerations on measurement The following general conditions apply to measurement discussed in this guide: a) Before testing, verify that all protective grounding leads are dismantled and nobody is working on the transmission line to be measured. b) The measurement shall be stopped if the weather is not suitable for measurement, such as thunderstorm, rain, or snow along the transmission line. Environmental data, such as temperature, humidity, and atmospheric pressure, should be recorded. c) The transmission lines should be disconnected from substation equipment. d) If the transmission line is composed of cable and overhead line, it is advisable that the parameters of the cable and the overhead line be measured separately. e) The substation grounding grid should serve as the grounding connection point for testing the power source, short-circuit ground, and grounding protection of devices. Tower grounding devices are prohibited to be grounding connection point. f) It is recommended to use the ground switch to short the end terminal of the circuit, if needed. When the down conductor is employed, the additional impedance should be removed from the result of the measurement. g) The grounding status of transmission lines that are close and parallel to the line being measured should be recorded, as that may affect the result of the measurement.
4.4 Test safety precautions The following safety precautions apply to the tests described in this guide: a) Measures should be taken to minimize induced voltage and current when it is dangerous for operators and instruments; otherwise, measurement shall be stopped. b) To increase safety while performing measurements, the operator should wear personal protective equipment. c) The transmission line shall be solidly grounded while the measuring mode is changed, so as to increase the safety of instruments and personnel. d) The down conductor and ground wire shall be solidly connected. Any conductors used for measurement should be insulated and able to withstand testing voltage and induced voltage. e) It is necessary to install a protective gap between ground wire and down conductor to protect the operators and measuring equipment from lightning strike.