Negative-Sequence Overcurrent Protection For Motors 46M; Identification; Function Block; Functionality - ABB RELION 620 Series Technical Manual

1MAC504801-IB E
4.1.9
4.1.9.1
4.1.9.2
4.1.9.3
4.1.9.4
620 series ANSI
Technical Manual

Negative-sequence overcurrent protection for motors 46M

Identification

Function description
Negative-sequence overcurrent
protection for motors

Function block

GUID-CE192548-AC31-4839-A5E1-54984D172B05 V2 EN
Figure 112: Function block

Functionality

The unbalance protection based on negative-sequence overcurrent protection for motors
46M 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 full
load current, which can severely heat the motor. 46M detects the large negative sequence
current and disconnects the motor.
The function contains a blocking functionality. It is possible to block the function outputs,
timers or the function itself, if desired.

Operation principle

The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
The operation of unbalance protection based on negative-sequence current can be
described by using a module diagram. All the modules in the diagram are explained in the
next sections.
IEC 61850 IEC 60617
identification identification
MNSPTOC I2>M
Section 4
Protection functions
ANSI/IEEE C37.2
device number
46M
245