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pg. 24
TRINITY
ACCUVAR - Operational Manual
Faults related to the external cabling
Only two cables originate in the panel: the Power Incomer to the panel and the CT connections.
The power flow from the source (such as the main transformer) to the capacitor panel as well
as to the entire load must be through the bus on which the CTs are mounted. It is best to
provide separate CTs for the Relay to avoid problems.
b. Faults Related to the actual site conditions:
These faults occur when the actual site conditions are different from those assumed by the
designer of the system. These faults relate to the location of the load feeders on the busbar,
buscouplers, and connections from transformers etc. The locations of the CTs are the most
important factor as far as the Relay is concerned.
Another problem frequently encountered is that of insufficient load on the power system. This
might occur because the Plant has not been commissioned fully, or because the system allows
for future expansion. In either case the actual current through the CT is very low compared to
the rating of the CT.
In such conditions, the relay, (specially, if there are no small banks in the capacitor panel) will
not take any control action at all. However, the transformer losses will cause the monthly
average PF to show up as very poor. The remedy is to connect a small bank directly
(independent of the automatic control scheme) for compensating transformer losses.
c. Faults related to the actual equipment:
These relate to the defects in the connected equipment. Again, an exhaustive list is beyond
the scope of this document. A few are listed below:
Blown fuses, shorted CT, shorted voltage connections, switches that do not make contact,
open connections etc. Check everything - before, during and after commissioning and you
will be rewarded with a finely tuned system which will give you years of trouble-free service.