Technical Data; Negative-Sequence Overcurrent Protection For Machines Mnsptoc; Identification; Function Block - ABB RELION REX640 Technical Manual

1MRS759142 C
4.4.4.10
4.4.5
4.4.5.1
4.4.5.2
4.4.5.3
REX640
Technical Manual

Technical data

Table 694: PREVPTOC Technical data
Characteristic
Operation accuracy
1)2)
Start time
I
Fault
value
Reset time
Reset ratio
Retardation time
Operate time accuracy in definite time mode
Suppression of harmonics
1) Negative-sequence current before = 0.0, f
measurements
2) Includes the delay of the signal output contact
Negative-sequence overcurrent protection for machines
MNSPTOC

Identification

Function description
Negative-sequence overcurrent
protection for machines

Function block

GUID-EE5068AA-5BCF-4E4E-BC22-95B187296E9C V1 EN
Figure 417: Function block

Functionality

The negative-sequence overcurrent protection for machines function MNSPTOC
protects electric motors from phase unbalance. A small voltage unbalance can
produce a large negative-sequence current flow in the motor. For example, a 5 percent
voltage unbalance produces a stator negative-sequence current of 30 percent of the
Value
Depending on the frequency of the measured
current: f
±1.5% of the set value or ±0.002 × I
Minimum
Start
= 2.0 × set
23 ms
Typically 40 ms
Typically 0.96
<35 ms
±1.0% of the set value or ±20 ms
DFT: -50 dB at f = n × f
= 50 Hz, results based on statistical distribution of 1000
n
IEC 61850
identification
MNSPTOC
Section 4
Protection functions
±2 Hz
n
n
Typical Maximum
25 ms 28 ms
, where n = 2, 3, 4, 5,...
n
IEC 60617 ANSI/IEEE C37.2
identification device number
I2>M 46M
757