6.3 Secondary protection testing
Utilities around the world are facing a significant and growing
amount of work every year associated with the testing and
management of protection and control devices. At the same
time, they have to cope with a reducing capability to undertake
the work (less qualified engineers and technicians
through natural wastage and staffing cuts) in the area of operative
maintenance. In fact, the Network Protection manager
must consider optimizing working processes where the quality
of work must at least stay the same, if not improve, in order to
face up to the increasing risks and costs of protectiontriggered
network supply interruptions [4; 5; 6; 7; 8].
A modem protection operational maintenance regime requires
the Protection manager learning to make a primary test of
protection devices as simple and as practicable as possible. In
Elektro Ljubljana's Distribution Company, the regular yearly
test of medium voltage current transformers (CT's) includes a
test of their accuracy and the unbalance test at nominal current.
Equivalent simplification of that measurement would be
if the measurements would be taken when they have normally
loaded CT's, considering the measurement of secondary current
and an unbalanced current in the Hollmngreen's connection.
With that kind of simplification, it is proposed that the primary
routine test would become unnecessary and the quality
of testing procedure would stay absolutely the same. The
whole testing procedure would than be executed secondary in
the way that is described in earlier chapter. Work would be
much safer and quicker.
The new way of testing is ideal for so-called distributed testing.
The system can merge the work of more than one user at
the time: e.g. the first user is doing a test of operative and
unbalance measurements during a normal condition and input
the testing results directly in the system (paperless work),
meanwhile the second user executes a protection test by manual
input directly to the system or (as recommended) by using
an intelligent system with no manual input. After both users
complete their jobs they get to the office and synchronize their
local databases to the central database where the fusion of all
data is done. The results are then available to everyone that
has permission to use the system.