ABB RELION 650 SERIES, Technical Manual

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Table 164: SAPTUF Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 - 12 - 1 1 Selection of one of the Global Base
Value groups
9.1.6 Operation principle
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Underfrequency protection SAPTUF is used to detect low power system frequency.
SAPTUF 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 START or TRIP signal is issued.
9.1.6.1 Measurement principle
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The fundamental frequency of the measured input voltage is measured
continuously, and compared with the set value,
StartFrequency . The frequency
function is dependent on the voltage magnitude. If the voltage magnitude decreases
below the setting
IntBlockLevel , SAPTUF gets blocked, and the output
BLKDMAGN is issued. All voltage settings are made in percent of the setting
UBase , which should be set as a phase-phase voltage in kV.
To avoid oscillations of the output START signal, a hysteresis has been included.
9.1.6.2 Time delay
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The time delay for underfrequency protection SAPTUF 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 voltage level causes a short time delay. For the definite time delay, the
setting
tDelay sets the time delay.
For the voltage dependent time delay the measured voltage level and the settings
UNom , UMin , Exponent , tMax and tMin set the time delay according to figure 151
and equation . The setting TimerMode is used to decide what type of time delay to
apply.
Trip signal issuing requires that the underfrequency condition continues for at least
the user set time delay
tDelay . If the START condition, with respect to the
measured frequency ceases during this user set delay time, and is not fulfilled again
within a user defined reset time,
tReset , the START output is reset, after that the
defined reset time has elapsed. Here it should be noted that after leaving the
1MRK 506 382-UEN A
Section 9
Frequency protection
Line distance protection REL650 2.2 IEC 301
Technical manual