Operation Principle - ABB RES670 Technical Manual

1MRK 511 408-UUS A
Name Values (Range)
Exponent 0.0 - 5.0
t_MaxTripDelay 0.010 - 60.000
t_MinTripDelay 0.010 - 60.000
Table 165: SAPTUF (81L) Non group settings (basic)
Name Values (Range)
GlobalBaseSel 1 - 12
10.1.6
10.1.6.1
10.1.6.2
Phasor measurement unit RES670 2.2 ANSI
Technical manual
Unit Step
- 0.1
s 0.001
s 0.001
Unit Step
- 1

Operation principle

Underfrequency protection SAPTUF (81) is used to detect low power system
frequency. SAPTUF (81) can either have a definite time delay or a voltage magnitude
dependent time delay. If the voltage magnitude dependent time delay is applied, the
time delay will be longer if the voltage is higher, and the delay will be shorter if the
voltage is lower. If the frequency remains below the set value for a time period
corresponding to the chosen time delay, the corresponding trip signal is issued. To
avoid an unwanted trip due to uncertain frequency measurement at low voltage
magnitude, a voltage controlled blocking of the function is available, that is, if the
voltage is lower than the set blocking voltage IntBlockLevel, the function is blocked
and no PICKUP or TRIP signal is issued.
Measurement principle
The fundamental frequency of the measured input voltage is measured continuously,
and compared with the set value, PUFrequency. The frequency function is dependent
on the voltage magnitude. If the voltage magnitude decreases below the setting
IntBlockLevel, SAPTUF (81) gets blocked, and the output BLKDMAGN is issued. All
voltage settings are made in percent of the setting VBase, which should be set as a
phase-phase voltage in kV.
To avoid oscillations of the output PICKUP signal, a hysteresis has been included.
Time delay
The time delay for underfrequency protection SAPTUF (81) can be either a settable
definite time delay or a voltage magnitude dependent time delay, where the time delay
depends on the voltage level; a high voltage level gives a longer time delay and a low
Default Description
1.0 For calculation of the curve form for voltage
based timer
1.000 Maximum time operation limit for voltage
based timer
1.000 Minimum time operation limit for voltage
based timer
Default Description
1 Selection of one of the Global Base Value
groups
Section 10
Frequency protection
M13354-10 v9
M13354-3 v9
M13354-6 v8
303