Overcurrent Protection, Ground
Overview of Functions
The Overcurrent protection, ground function (ANSI 50N/51N):
•
Detects short circuits in electrical equipment
•
Can be used as backup overcurrent protection in addition to the main protection
Structure of the Function
The Overcurrent protection, ground function is used in protection function groups. 2 kinds of functions are
available for the 3-phase overcurrent protection:
•
Overcurrent protection, ground – advanced (50N/51N OC-gnd-A)
•
Overcurrent protection, ground – basic (50N/51N OC-gnd-B)
Only the function type Advanced is available in the bay controllers. The function type Basic is provided for
standard applications. The function type Advanced offers more functionality and is provided for more complex
applications.
Both function types are pre-configured by the manufacturer with 2 Definite-time overcurrent protection
stages and with 1 Inverse-time overcurrent protection stage.
In the function type Overcurrent protection, ground – advanced the following stages can be operated
simultaneously:
•
Maximum of 3 stages Definite-time overcurrent protection – advanced
•
1 stage Inverse-time overcurrent protection – advanced
•
1 stage User-defined characteristic curve overcurrent protection
In the function type Overcurrent protection, ground – basic the following stages can be operated simultane-
ously:
•
Maximum of 3 stages Definite-time overcurrent protection – basic
•
1 stage Inverse-time overcurrent protection – basic
The non-preconfigured stages are shown in gray in the following figures. Apart from the tripping delay charac-
teristic, the stages are identical in structure.
The measured-value selection (only advanced stage) is general functionality and has a uniform effect on the
stages (see Figure 7-76 and chapter 7.5.3.1 Description). This ensures that all stages of the function receive
the same measured current 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
7.5
7.5.1
7.5.2
Protection and Automation Functions
7.5 Overcurrent Protection, Ground
634 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
To Next Page
Loading...
