Alstom MiCOM P546 - 4.2.7 Slip control by timer (P543;P545)

Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546 (OP) 5-153
OP
If Check Sync Voltage Blocking is set to UV, UV + OV, UV + DiffV or UV + OV + DiffV, both
line volts and bus volts magnitudes are > Check Sync Undervoltage setting
AND
If Check Sync Voltage Blocking is set to DiffV, UV + DiffV, OV + DiffV or UV + OV + DiffV,
the voltage magnitude difference between line volts and bus volts is < Check Sync Diff
Voltage setting
AND
If Check Sync 1(2) Slip Control is set to Timer or Frequency + Timer, the above conditions
have been true for a time > or = Check Sync 1(2) Slip Timer setting
Note: Live Line/Dead Bus and Dead Bus/Line functionality is provided as
part of the default PSL (see Figure 100).
4.2.7 Slip control by timer (P543
/P545)
If Slip Control by Timer or Frequency + Timer is selected, the combination of Phase Angle
and Timer settings determines an effective maximum slip frequency, calculated as:
2 x A
T x 360
Hz. for Check Sync 1
or
A
T x 360
Hz. for Check Sync 2
Where:
A = Phase Angle setting ()
T = Slip Timer setting (seconds)
For example, with Check Sync 1 Phase Angle setting 30 and Timer setting 3.3 sec, the
“slipping” vector has to remain within 30 of the reference vector for at least 3.3 seconds.
Therefore a synchro check output will not be given if the slip is greater than 2 x 30 in 3.3
seconds. Using the formula: 2 x 30  (3.3 x 360) = 0.0505 Hz (50.5 mHz).
For Check Sync 2, with Phase Angle setting 10 and Timer setting 0.1 sec, the slipping
vector has to remain within 10 of the reference vector, with the angle decreasing, for 0.1
sec. When the angle passes through zero and starts to increase, the synchro check output
is blocked. Therefore an output will not be given if slip is greater than 10 in 0.1 second.
Using the formula: 10  (0.1 x 360) = 0.278 Hz (278 mHz).
Slip control by Timer is not practical for “large slip / small phase angle” applications, because
the timer settings required are very small, sometimes < 0 s. For these situations, slip control
by frequency is recommended.
If Slip Control by Frequency + Timer is selected, for an output to be given, the slip frequency
must be less than BOTH the set Slip Freq value and the value determined by the Phase
Angle and Timer settings.