4.85
Date Code 20170814
Instruction Manual
SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
Figure 4.51
Double-Blinder Typical Settings
Inadvertent Energization
Inadvertent energization occurs when the generator main circuit breaker or
auxiliary transformer circuit breaker is incorrectly closed to energize the
generator while the generator is out of service. When this occurs, the
generator can act as an induction motor, drawing as much as four to six times
rated stator current from the system. These high stator currents induce high
currents in the rotor, quickly damaging the rotor.
The SEL-700G INADT element is intended to provide an inadvertent
energization protection. Two accepted approaches are voltage-supervised
overcurrent relays and auxiliary contact-supervised overcurrent relays. The
INADT element supports both.
The objective of inadvertent energization protection is to detect that the
generator has been reenergized suddenly after being removed from service.
Table 4.16 shows the settings associated with the element.
78FWD: Forward
Reach
78REV: Reverse
Reach
X’
d
:
Generator Transient Reactance
XT: Transformer
Reactance
ZS: System
Impedance
M-N:
Total Impedance Between Generator and System
S-S
1
:
Perpendicular Bisector of M-N
α
:
Angle of Separation Between Generator and System Measured at 78R2
γ
:
Angle of Separation Between Generator and System Measured at 78R1
Содержание SEL-700G Series
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