1
ASEA BROWN BOVERI
ABB Relays
34 SPAD 4 EN1 C
1992 - 10 - 27
Written
Checked
Approved
Differential relay
SPAD 330 C
Three-phase biased differential relay
for the protection of power transformers
and generator-transformer units.
Matching of the power transformer
vector group with DlL switches and the
electronics. No intermediate current
transformers are needed.
The transforming ratio errors of the
C.T.s separately correctable on the HV
and LV side of the power transformer.
Separately adjustable differential
current high-set instantaneous stage.
Stabilized operating principle prevents
spurious function on faults occurring
outside the area of protection.
Blocking function, for prevention of
spurious operations caused by con-
nection inrush currents, based on the
occurrence of the second harmonic.
Local display of measured and set
values on relay front panel.
Continuous self-supervision of the
electronic circuitry and the operation
of the microprocessor.
Features
C
