Delayed Closing Strategy; Fallback Strategy; Resetting Estimated Residual Flux - Hitachi Relion 650 Series Technical Manual

1MRK 511 557-UEN Rev. A
TrafoType
D5
Z1
Z11
The CLANGL1, CLANGL2 and CLANGL3 outputs provide the target making angles as per the
closing targets definition of SSCPOW. Target angles will be re-calculated in case of IED reboot, when
any of the residual flux values changes (including actual de-energization, manual reset), or upon
change of TrafoType.
The default switching sequence is L1-L3-L2. In order to maintain this sequence in case of coupled
phases, an additional delay is applied to the target making instant of the non-prestriking phase. The
minimum delay is specified by the NoPrestrikeDelay setting.
12.20.7.4

Delayed Closing Strategy

After energizing the first limb of a coupled transformer, any residual flux in the remaining limbs will
usually decay to negligible values ("equalize") within 1-2 cycles. This can be utilized in controlled
switching by delaying the later energizing phases accordingly, which simplifies the making strategy.
In TRAFOSWT, the ClosingStrategy setting determines whether to employ the "Delayed" closing
strategy as explained above, or whether the three phases are energized with minimum delay from
first to last phase ("Rapid" closing strategy). In case of "Delayed" strategy, the HCycleDelay setting
specifies the minimum number of half cycles for delaying the later switching phase(s); it needs to be
set to ensure flux equalization at the time of energizing these phases.
12.20.7.5

Fallback Strategy

The fallback strategy is a default switching strategy that is not based on the estimated residual
fluxes. TRAFOSWT requests application of the fallback closing strategy, by clearing its VALIDSTGY
output, when any of the following conditions is true.
1. Binary input FALLBACK is activated.
2. CBSTSCFL1 = CBSTSCFL2 = CBSTSCFL3 = 2 (the breaker is already in a closed position).
3. Binary output INVFLUX is activated.
4. Binary input BLOCKINT is activated.
If the function meets any one of the above-mentioned conditions, the closing angles calculated
earlier are retained but VALIDSTGY output is cleared to indicate that the angles may not be valid.
12.20.7.6

Resetting Estimated Residual Flux

In case where the estimated residual fluxes are considered invalid, TRAFOSWT includes a provision
to reset the residual fluxes to initial values. Upon activating the RESETFLUX input, the function
performs the following updates:
1. RESFLUXL1/FLUX1 = ResidualFluxLimb1
2. RESFLUXL2/FLUX2 = ResidualFluxLimb2
3. RESFLUXL3/FLUX3 = ResidualFluxLimb3
A binary output FLUXRESET is activated whenever the flux is reset, for as long as the binary input
RESETFLUX is active. This binary input (RESETFLUX) is also linked to the Clear menu (Clear
residual fluxes) in LHMI and WHMI.
The residual fluxes stored during the previous open operation are reset to 0 when a positive edge of
the binary input VOLTGON is detected by the function (VOLTGON binary input status changes from
Technical Manual
Switched Winding Type with
neutral grounding
Delta
Zig-zag with grounded neutral
Zig-zag with grounded neutral
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Electrically or
magnetically coupled?
Yes
-
-
GUID-BE68819D-9C23-436C-884E-DC64D57A90E5 v1
GUID-F5544AFD-1522-4A81-BE6E-3A2BC6BD5E25 v1
GUID-38606B32-A13B-493D-99C4-11AABC6DD201 v1
Section 12
Monitoring
Phase Angle
+150° (D5)
+30°
-30°
327