METREL MI 3298, Instruction Manual With Exercises

Page: 101 / 232

Power Network Application Trainer
– Earthing / Grounding network impedance measurement
101
To get total pylon impedance, we need to calculate it from the individual values. Four
legs pylon could be presented as parallel connection of four impedances, so the
calculated object impedance is:
Foot Nm. 1 22,4
Ω
Foot Nm. 2 10,90
Ω
Foot Nm. 3 22,1
Ω
Foot Nm. 4 5,47
Ω
Total impedance 2,74
Ω
Table 24-
2: Pylon foot’s impedance
Measuring pylon resistance with single flex clamp is time consuming measurement;
since for each measurement we need to move flex clamps to the next foot.
To speed up the measurement and skip the manual pylon earth resistance calculation,
we propose to use four flex
– clamp (optional accessories).
4.1.3.2 S
– Flex measuring method by using one Flex-clamp with
simulated broken foot resistance and resistive earthing type
Figure 68-2: S-Flex measurement setup with MI 3290
This exercise presents procedure how to perform complete earth measurement on the
transmission pylon with four foots with only one flex clamp, with the simulation of broken