4.4.2.10
Technical revision history
Table 555: PDNSPTOC Technical revision history
Technical revision
Change
B
Internal improvement
C
Internal improvement
D
Internal improvement
4.4.3
Phase reversal protection PREVPTOC
4.4.3.1
Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Phase reversal protection
PREVPTOC
I2>>
46R
4.4.3.2
Function block
Figure 325: Function block
4.4.3.3
Functionality
The phase reversal protection function PREVPTOC is used to detect the reversed
connection of the phases to a three-phase motor by monitoring the negative phase
sequence current I
2
of the motor.
PREVPTOC starts and operates when I
2
exceeds the set limit. PREVPTOC operates
on definite time ( DT) characteristics. PREVPTOC is based on the calculated I
2
, and
the function detects too high I
2
values during the motor start-up. The excessive I
2
values are caused by incorrectly connected phases, which in turn makes the motor
rotate in the opposite direction.
The function contains a blocking functionality. It is possible to block function
outputs, timer or the function itself, if desired.
4.4.3.4
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of PREVPTOC can be described with a module diagram. All the
modules in the diagram are explained in the next sections.
Protection functions
1MRS757644 H
620
620 series
Technical Manual
