© OMICRON 2024 Page 12 of 25
3.1 First criterion
Check if the cable to test has a length with is less than 5 km / 3
miles.
3.2 Second criterion: Estimated open-cable voltage.
Figure 4 below illustrates the estimation of the open-cable voltage. In principal, the circular current which is
caused by the interference of a parallel system is measured in all three phases.
Death or severe injury caused by high voltage or current possible.
Before grounding a power cable, make sure that the cable is not powered
with the life-dead-life test as follows:
1. Use a certified voltage tester, approved for the voltage tests to be
performed.
2. Verify on a life system that the voltage tester is operational.
3. Verify on the cable to be unpowered that it is dead, using the voltage
tester.
4. Verify on the life system again that the voltage tester is still working.
When grounding a power cable, observe the five safety rules.
Figure 4: Estimating the open-line voltage
In order to allow a circular current, both ends of the cable must be grounded. With a standard current clamp
it is usually not possible to measure the current directly at the grounding switch. Therefore, the following
procedure by using a grounding set is recommended:
1. Switch off, short-circuit and ground the power cable on both sides, using an installed grounding
switch or, if no grounding switch is available on site, using grounding cables (further on, the
grounding switch or these extra grounding cables are referred to as grounding switch).
Note
For longer lines, the output
power of COMPANO 100
might be not sufficient,
especially in case of
interferences or coupling
from parallel systems.
While connecting the grounding set to the power
cable, the grounding switch must be closed!
To Next Page
Loading...
Need help?
General
