ABB RES670 2.1 Commissioning Manual page 199

1MRK 511 366-UUS -
Commissioning manual
UTC
UV
WEI
VT
X.21
3I
O
3V
O
Coordinated Universal Time. A coordinated time scale,
maintained by the Bureau International des Poids et Mesures
(BIPM), which forms the basis of a coordinated dissemination
of standard frequencies and time signals. UTC is derived from
International Atomic Time (TAI) by the addition of a whole
number of "leap seconds" to synchronize it with Universal Time
1 (UT1), thus allowing for the eccentricity of the Earth's orbit,
the rotational axis tilt (23.5 degrees), but still showing the
Earth's irregular rotation, on which UT1 is based. The
Coordinated Universal Time is expressed using a 24-hour
clock, and uses the Gregorian calendar. It is used for aeroplane
and ship navigation, where it is also sometimes known by the
military name, "Zulu time." "Zulu" in the phonetic alphabet
stands for "Z", which stands for longitude zero.
Undervoltage
Weak end infeed logic
Voltage transformer
A digital signalling interface primarily used for telecom
equipment
Three times zero-sequence current.Often referred to as the
residual or the ground-fault current
Three times the zero sequence voltage. Often referred to as the
residual voltage or the neutral point voltage
Section 14
Glossary
193