Negative-Sequence Overcurrent Protection For Machines 46M - ABB 615 series Technical Manual

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4.4.4
4.4.4.1
4.4.4.2
4.4.4.3
4.4.4.4
615 series ANSI
Technical Manual

Negative-sequence overcurrent protection for machines 46M

Identification
Function description
Negative-sequence overcurrent
protection for machines
Function block
46M
I PICKUP
2
BLOCK TRIP
BLK_RESTART
GUID-947A7DA2-8229-4A11-966B-3E3A4BA7F4AC V1 EN
Figure 305: Function block
Functionality
The negative-sequence overcurrent protection for machines function 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 46M 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
603