ABB REG650 User Manual

Function Range or value Accuracy
Critical impulse time,
undervoltage
10 ms typically at 2 to 0 x U
set
-
Impulse margin time,
undervoltage
15 ms typically -
Operate value,
overvoltage
(2-200)% of UBase ± 0.5% of U
r
at U<U
r
± 0.5% of U at U>U
r
Timers (0.000-60.000) s ± 0.5% ± 25 ms
8.9 Negative-sequence time overcurrent protection for
machines NS2PTOC
8.9.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Negative sequence time overcurrent
protection for machines
NS2PTOC 2I2> 46I2
8.9.2 Functionality
Negative-sequence time overcurrent protection for machines NS2PTOC is intended
primarily for the protection of generators against possible overheating of the rotor
caused by negative sequence current in the stator current.
The negative sequence currents in a generator may, among others, be caused by:
• Unbalanced loads
• Line to line faults
• Line to earth faults
• Broken conductors
• Malfunction of one or more poles of a circuit breaker or a disconnector
NS2PTOC can also be used as a backup protection, that is, to protect the generator in
case line protections or circuit breakers fail to clear unbalanced system faults.
To provide an effective protection for the generator for external unbalanced
conditions, NS2PTOC is able to directly measure the negative sequence current.
NS2PTOC also has a time delay characteristic which matches the heating
characteristic of the generator
2
2
I t K=
as defined in standard IEEE C50.13.
where:
I
2
is negative sequence current expressed in per unit of the rated
generator current
t is operating time in seconds
1MRK 502 048-UEN A Section 8
Current protection
243
Technical manual

ABB REG650 Specifications

General

Brand	ABB
Model	REG650
Category	Protection Device
Language	English