Toshiba GR-200-5 Instruction Manual page 620

Phase-angle variance (Δθ) (see Figure 4.5-4)
The phase-angle variance of Vr and Vi (Δθ) is measured by the phase-angle variance-relay
having the setting [SyncRy1-Angle]. If the following equations are satisfied, the SyncRy1-
Angle relay determines that the phase-angle variance is inside the permissible range.
V × V
r
Frequency-variance (Δf)
The frequency-variance of Vr and Vi (Δf) is measured by the frequency-variance relay having
the setting [SyncRy1-df]. If the following equations are satisfied, the SyncRy1-df relay
determines that the frequency-variance is inside the permissible range.
where,
f ⁡
Vr
⁡f
Vi
Δf
Notice and tips
If the frequency-variance between the Vr and the Vi is shown very large, the SYNCHK may
fail to make the decision of the synchronism, although Off is set for the setting [SyncRy1-dfEN]
to abandon to checking the frequency-variance. This is because; the vector passes the [SyncR1-
Angle] zone very quickly. As a result, the SYNCHK relay may fail to issue the permission
command. To avoid the failure, the user has to set values for settings [SyncR1-Angle] and
[SYNC01_TSYN] depending on the assumed frequency-variance (Δf):
where,
Tips: Cycles for the synchronism closure can be calculated:
Time length for getting a synchronism:
V × V cos ∆θ > 0
r i
sin ( setting[SyncRy1-Angle] ) ≥ V
i
∆f = | f | ≤ setting⁡[SyncRy1-df]
− f
Vi Vr
Frequency of Vr
Frequency of Vi
Frequency-variance between Vr and Vi
Setting⁡[SyncR1-Angle]
∆f > ⁡
180° × Setting⁡[SYNC01_TSYN]
Δf= Frequency-variance (or cycle-slip in Hertz)
Cycle⁡for⁡synchronism = 1 ∆f[Hz]
- 600 -
× V sin ∆θ
r i
⁄
6F2T0207 (0.01)
(4.5-4)
(4.5-5)
(4.5-6)
(4.5-7)
(4.5-8)
GRE200 (5,6)