ABB REL670 2.2 IEC - Voltage-Restrained Time Overcurrent Protection VRPVOC

Set the unsymmetrical current, which is relation between the difference of the
minimum and maximum phase currents to the maximum phase current to typical
Iub> = 50%.
Note that it must be set to avoid problem with asymmetry under
minimum operating conditions.
Set the time delay tOper = 5 - 60 seconds and reset time tReset = 0.010 - 60.000
seconds.
9.14 Voltage-restrained time overcurrent protection
VRPVOC
GUID-613620B1-4092-4FB6-901D-6810CDD5C615 v4
9.14.1 Identification
GUID-7835D582-3FF4-4587-81CE-3B40D543E287 v4
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Voltage-restrained time overcurrent
protection
VRPVOC I>/U< 51V
9.14.2 Application
GUID-622CDDDD-6D03-430E-A82D-861A4CBE067C v7
A breakdown of the insulation between phase conductors or a phase conductor and
earth results in a short-circuit or an earth fault. Such faults can result in large fault
currents and may cause severe damage to the power system primary equipment.
A typical application of the voltage-restrained time overcurrent protection is in the
generator protection system, where it is used as backup protection. If a phase-to-
phase fault affects a generator, the fault current amplitude is a function of time, and
it depends on generator characteristic (reactances and time constants), its load
conditions (immediately before the fault) and excitation system performance and
characteristic. So the fault current amplitude may decay with time. A voltage-
restrained overcurrent relay can be set in order to remain in the picked-up state in
spite of the current decay, and perform a backup trip in case of failure of the main
protection.
The IED can be provided with a voltage-restrained time overcurrent protection
(VRPVOC). The VRPVOC function is always connected to three-phase current
and three-phase voltage input in the configuration tool, but it will always measure
the maximum phase current and the minimum phase-to-phase voltage.
VRPVOC function module has two independent protection each consisting of:
• One overcurrent step with the following built-in features:
1MRK 506 369-UEN B Section 9
Current protection
Line distance protection REL670 2.2 IEC 527
Application manual