Frequency slip(s) =
−
( )
f f
f
Gen Bus
Bus
(Equation 358)
The measured bus voltage (U
Bus
), bus frequency (f
Bus
), generator voltage (U
Gen
),
generator frequency (f
Gen
) and phase angle difference values between the two
sides of the circuit breaker are available as monitored data values U_BUS_MEAS,
FR_BUS_MEAS, U_GEN_MEAS, FR_GEN_MEAS, U_DIFF_MEAS, FR_DIFF_MEAS and
PH_DIFF_MEAS. The calculated frequency slip acceleration (ds/dt) is available as
monitored data value FR_SLIP_ACCL. Also, the indications of the conditions that
are not fulfilled and thus preventing the breaker closing permission are available
as monitored data values U_DIFF_SYNC, PH_DIF_SYNC and FR_DIFF_SYNC. These
monitored data values are updated only when the setting
Synchrocheck mode
is set
to "Asynchronous" and the measured ENERG_STATE is "Both Live".
The measured voltage, frequency are updated in the monitored data irrespective of
any condition.
Close CB condition
When
Synchrocheck mode
is set to "Asynchronous", the close CB condition is
generated as explained below.
From the frequency slip s, the acceleration ds/dt, the bus frequency FR_BUS_MEAS
(f
Bus
) and the set
Closing time of CB
, the function calculates the necessary lead
angle (α
Lead
) by which the close CB command is shifted forward in time so that the
main contacts close on phase coincidence.
α
Lead Bus
f s
TCB ds
dt
TCB
= ⋅ ⋅ +
⋅
⋅
360
2
1000 1000
(Equation 359)
f
Bus
Bus side frequency
s Frequency slip
ds/dt Frequency slip acceleration
TCB Setting
Closing time of CB
ASGCSYN can be set to the bypass mode by setting the parameters
Synchrocheck mode
and
Live dead mode
to "Off" or, alternatively, by
activating the BYPASS input. In the bypass mode, the close CB conditions
are always fulfilled. Otherwise, the operation is similar to the normal
mode.
If the parameter
Synchronization Dir
is “Both directions”, function issues
CLOSE_CB output direct-ly when the measured frequency difference is
zero and the measured phase difference is less than 5 degrees for
duration set by
Minimum Syn time
.
If the parameter
Synchronization Dir
is “Always over-synchronous”,
closing signal is blocked when the measured frequency difference is
between 0 and 1/3*
Freq Diff Ov Synch
.
Control functions 1MRS759142 F
1564 REX640
Technical Manual
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