System back to
normal and
27RT resets
Time in ms
Vn
Voltage
xVn
TRIP
A
B
C
Voltage level 1
(Recovery time 1,
Voltage level 1)
(Recovery time 2,
Voltage level 2)
(Recovery time 3,
Voltage level 3)
(Recovery time 4,
Voltage level 4)
0
Point of
fault
Voltage pickup value
= Voltage level 4
Voltage level 2
= Voltage level 3
Recovery
time 1
Recovery
time 2
Recovery time 3
= Recovery time 4
GUID-56F18EC3-0D24-431A-AFAC-13A85BCBDFF5 V1 EN
Figure 332: A typical required ride-through voltage capability of generating unit
The LVRT requirement depends on the power system characteristics and the protection
employed, varying significantly from each other. The requirement also differs from
country to country. 27RT function incorporates four types of LVRT curves which satisfy
most of the power system needs. Grid operators can fine-tune the LVRT curve by setting
the parameters as per their requirement, making the use simpler in comparison with
different conventional undervoltage protection with different operate time setting and
logics.
4.5.7.6 Signals
Table 566: 27RT Input signals
Name
Type Default Description
V_A_AB SIGNAL 0 Phase-to-ground voltage A or phase-to-phase voltage
AB
V_A_BC SIGNAL 0 Phase-to-ground voltage B or phase-to-phase voltage
BC
V_A_CA SIGNAL 0 Phase-to-ground voltage C or phase-to-phase voltage
CA
V
1
SIGNAL 0 Positive phase sequence voltage
BLOCK BOOLEAN 0=False Block signal for activating the blocking mode
Table 567: 27RT Output signals
Name
Type Description
TRIP BOOLEAN Trip
PICKUP BOOLEAN Pickup
Section 4 1MAC059074-MB A
Protection functions
664 615 series ANSI
Technical Manual
To Next Page
Loading...
