ABB RELION REB500 Technical Manual page 130

Section 5
Bay protection functions
The frequency difference df is obtained by determining the rate at which the phase-shift
between the voltage vectors varies:

df
The conditions for synchronism are fulfilled, providing the values of the resulting variables are
within the limits set for
Typical values are:
• maxVoltDif: 0.2 U
• maxPhaseDif: 10°
• maxFreqDif:
•
•
•
Monitoring the voltage in two power systems (minVoltage, maxVoltage)
The determination of voltage amplitude can be either based on monitoring a single phase or
all three phases depending on how the particular AnalogAddr is configured. If the three phases
are included, then the highest voltage of the three is detected for the maximum limit,
respectively the lowest of the three for the minimum limit.
In order to be able to monitor the voltages in a wide frequency range, instantaneous values are
measured (instead of digitally filtered analogue voltages).
The voltage detectors may be used to determine whether a system is de-energized or
energized:
• A system is considered to be de-energized, if its voltage (highest of the three phases in
the case of three-phase measurement) falls below the setting of the parameter
maxVoltage .
• A system is considered to be energized, if its voltage (lowest of the three phases in the
case of three-phase measurement) exceeds the setting of the parameter
• On no account will an enable signal permitting closure of the circuit-breaker be issued,
should the voltage lie between the limits of
Typical values are:
• minVoltage 0.70 U
• maxVoltage 0.30 U
124
d
  
 
 
dPhi B L
df
maxVoltDif , maxPhaseDif and maxFreqDif .
N
50 mHz for connecting largely synchronous parts of a stable closely meshed system
or where high demands with regard to synchronism have to be fulfilled.
100 mHz in autoreclosure schemes with long dead times (for example, three-phase
slow reclosure) or for autoreclosure of short transmission lines
200 mHz in autoreclosure schemes with short dead times, but where high slip
frequencies are to be expected
The setting of the synchronism measuring period (
chosen to correspond to the settings for the maximum phase-shift and
maximum frequency difference.
N
N
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
maxVoltage and minVoltage .
1MRK 505 406-UEN B
supervisTime ) must be
minVoltage .
Bay protection functions REB500
Technical manual