Phase Angle Difference; Voltage Angle Difference; Frequency Slip - GE Multilin F650 Instruction Manual

5 SETPOINTS 5.5 CONTROL ELEMENTS
Δϕ

Phase Angle Difference

In the live line-live bus Condition, once the voltage difference has been successfully verified in magnitude, the system
establishes the angle difference between both voltage phasors. If the angle difference is lower than the Δϕ
(Max Angle
set
Difference) setpoint, then the system will verify the frequency slip S (Max Freq Difference).
Δ ϕ
s e t
Δ ϕ
a c t u a
V
H
V
L
V
V
1
2
Figure 5–20: VOLTAGE ANGLE DIFFERENCE
5
Δ

FREQUENCY SLIP

f
The relative frequency slip between phasors is calculated if the angle difference is lower than the Δϕ
(Max Freq
set
Difference) setpoint. From the information obtained from the relay, the algorithm can know the slip (mHz) of both phasors,
and it will take as reference (V ) the lowest frequency phasor.
Ref
If the relative slip is higher than 5 mHz, the unit performs an anticipative algorithm, determining the right moment to give the
closing command to the breaker, so that the breaker closes when the line and busbar voltages are in phase. If the slip is
higher than 5 Hz, as a close in phase is not possible, the algorithm ensures that the difference between voltages in the real
closing moment is not higher than the set value (Max Volt Difference). If the relative slip, Δf, is equal or lower than 0.005
Hz, the algorithm gives closing permission as soon as the angle difference conditions are met, because at such a low
speed, the hold time for getting an "in-phase" closing permission would be too long.
When the difference between voltage values equals "two times" the set angle as maximum angle difference (ΔV = ΔV
),
set
the anticipative algorithm starts running and uses the set breaker closing time to establish the initiation of permission, so
that it is executed in the moment when both voltage phasors are completely in phase, thus minimizing the voltage
difference in the breaker chamber to negligible values.
The main benefit is that after a considerable number of breaker operations, damage to internal connection elements, as
well as to the chamber isolating element is drastically reduced, ensuring a longer life for the breaker, and reducing costly
maintenance operations.
GE Multilin F650 Digital Bay Controller 5-85