Overcurrent Protection, Phases; Overview Of Functions; Structure Of The Function - Siemens 7SJ82 Manual

6.3

Overcurrent Protection, Phases

Overview of Functions

6.3.1
The Overcurrent protection, phases function (ANSI 50/51):
•
Detects short circuits in electrical equipment
•
Can be used as backup overcurrent protection in addition to the main protection
6.3.2

Structure of the Function

The Overcurrent protection, phases function is used in protection function groups. 2 kinds of functions are
available for the 3-phase overcurrent protection:
•
Overcurrent protection, phases – advanced (50/51 OC-3ph-A)
•
Overcurrent protection, phases – basic (50/51 OC-3ph-B)
The Basic function type is provided for standard applications. The Advanced function type offers more func-
tionality and is provided for more complex applications.
Both function types are preconfigured by the manufacturer with 2 Definite-time overcurrent protection
stages and with 1 Inverse-time overcurrent protection stage.
In the Overcurrent protection, phase – advanced function type, the following stages can be operated simul-
taneously:
•
Maximum of 4 stages Definite-time overcurrent protection – advanced
•
2 stages Inverse-time overcurrent protection – advanced
•
2 stages User-defined overcurrent protection characteristic curve
In the Overcurrent protection, phases – basic function type, the following stages can be operated simulta-
neously:
•
Maximum of 4 stages Definite-time overcurrent protection – basic
•
1 stage Inverse-time overcurrent protection – basic
Stages that are not preconfigured are shown in gray in the following figures. Apart from the tripping delay
characteristic, the stages are identical in structure.
The optional function block Filter offered in the advanced function allows to gain harmonics or to compensate
the amplitude attenuation for the RMS value.
The group-indication output logic generates the following group indications of the protection function by the
logical OR of the stage-selective indications:
•
Pickup
•
Operate
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
Protection and Automation Functions
6.3 Overcurrent Protection, Phases
323