VAMP 257
Feeder and motor manager
Technical description
VAMP Ltd
22
VAMP 24h support phone : +358 (0)20 753 3264
VM257.EN002
Figure 2.3.1-19 ANSI/IEEE2 very
inverse delay
Figure 2.3.1-20 ANSI/IEEE2
extremely inverse delay
2.3.2.
Short-circuit fault location
The manager includes a sophisticated stand-alone fault
location algorithm. The algorithm can locate a short-circuit
accurately in radially operated networks. The fault location is
given in reactance value, and also the distance to the fault is
displayed on the local HMI. This value can then be exported,
for example, with event to a DMS (Distribution Management
System). The system can then localize the fault. If a DMS is not
available, the distance to the fault is displayed as kilometres,
as well as a reactance value. However, the distance value is
valid only if the line reactance is set correctly. Furthermore,
the line should be homogenous, that is, the wire type of the line
should be the same for the whole length. If there are several
wire types on the same line, an average line reactance value
can be used to get an approximate distance value to the fault
(examples of line reactances: Overhead wire Sparrow: 0.408
ohms/km and Raven: 0.378 ohms/km).
The fault location is normally used in the incoming bay of the
substation. Therefore, the fault location is obtained for the
whole network with just one manager. This is very cost-
effective upgrade of an existing system.
The algorithm functions in the following order:
1.
The needed measurements (phase currents and voltages)
are continuously available.
2.
The fault distance calculation can be triggered in two ways:
by opening a feeder circuit-breaker due to a fault (that is, by
using a digital input) or the calculation can be triggered if
