Zone 1 Operation - ABB REG670 Applications Manual

1MRK 502 071-UEN -
8.9.2.2
8.9.2.3
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
The settings of all the zones is provided in terms of percentage of impedance based on
current and voltage ratings of the generator.

Zone 1 operation

Zone 1 is used as fast selective tripping for phase-to-phase faults and three–phase
faults in the generator, on the terminal leads and LV side of generator transformer.
Since generator is high impedance earthed, the fault current for phase-to-earth faults
will be too low and impedance protection is not intended to operate for these faults.
The measuring loops used for zone1 are given below.
Zone 1 measuring loops for phase-to-phase faults and three–phase faults on the
primary side of the generator transformer are:
Sl.No Phase-to-phase loop
1 L1–L2
2 L2–L3
2 L3–L1
UL1L2, UL2L3, UL3L1 are three phase-to-phase voltages. IL1L2,
IL2L3, IL3L1 are the three phase-to-phase currents.
For this application the zone 1 element is typically set to see 75% of the transformer
impedance.
Zone 2 operation
Zone 2 can be used to cover up to the HV side of the transformer and the HV bus bar,
and is usually set to cover 125% of the generator transformer impedance. The time to
trip must be provided in order to coordinate with the zone 1 element on the shortest
outgoing line from the bus.
Zone2 will provide protection for phase-to-earth, phase-to-phase and three-phase
faults on the HV side of the system. All these faults can be detected using three phase-
to-phase loops or Enhanced reach loop (The phase-to-earth loop with maximum phase
current).
Two options are provided for measuring loops used for zone 2, which is set by the user.
The measuring loops used for zone 2 with different options are:
Phase-to-phase loops
Phase-to-phase loop
L1–L2
L2–L3
L3–L1
Voltage phasor
UL1L2
UL2L3
UL3L1
Voltage phasor
UL1L2
UL2L3
UL3L1
Section 8
Impedance protection
Current phasor
IL1L2
IL2L3
IL3L1
Current phasor
IL1L2
IL2L3
IL3L1
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