Settings For Two Step Undervoltage Protection - ABB REQ650 Applications Manual

1MRK 505 291-UEN A
7.1.3.6
Application manual

Settings for Two step undervoltage protection

The following settings can be done for two step undervoltage protection (UV2PTUV).
GlobalBaseSel: Selects the global base value group used by the function to define
(IBase), (UBase) and (SBase).
ConnType: Sets whether the measurement shall be phase-to-earth fundamental value,
phase-to-phase fundamental value, phase-to-earth RMS value or phase-to-phase
RMS value.
Operation: Off/On.
UV2PTUV measures selectively phase-to-earth voltages, or phase-to-phase voltage
chosen by the setting ConnType.
This means operation for phase-to-earth voltage if:
< ×
U (%) UBase kV ( )
EQUATION1447 V1 EN
and operation for phase-to-phase voltage if:
< ×
U (%) UBase(kV)
EQUATION1990 V1 EN
Characteristic1: This parameter gives the type of time delay to be used for step 1. The
setting can be. Definite time/Inverse Curve A/Inverse Curve B. The choice is highly
dependent of the protection application.
OpModen: This parameter describes how many of the three measured voltages that
should be below the set level to give operation for step n (n=step 1 and 2). The setting
can be 1 out of 3, 2 out of 3 or 3 out of 3. It is sufficient that one phase voltage is low
to give operation. If the function shall be insensitive for single phase-to-earth faults 2
out of 3 can be chosen.
Un<: Set undervoltage operation value for step n (n=step 1 and 2), given as % of the
global parameter UBase. This setting is highly dependent of the protection
application. Here it is essential to consider the minimum voltage at non-faulted
situations. This voltage is larger than 90% of nominal voltage.
tn: Time delay for step n (n=step 1 and 2), given in s. This setting is highly dependent
of the protection application. In many applications the protection function does not
directly trip where there is short circuit or earth faults in the system. The time delay
must be coordinated to the short circuit protection.
t1Min: Minimum operating time for inverse time characteristic for step 1, given in s.
When using inverse time characteristic for the undervoltage function during very low
voltages can give a short operation time. This might lead to unselective trip. By setting
3
Section 7
Voltage protection
(Equation 67)
(Equation 68)
157