Overcurrent Protection, 1-Phase; Function Overview; Structure Of The Function - Siemens 7SJ82 Manual

Protection and Automation Functions

6.12 Overcurrent Protection, 1-Phase

6.12 Overcurrent Protection, 1-Phase

Function Overview

6.12.1
The Overcurrent protection, 1-phase function (ANSI 50N/51N):
•
Detects and monitors the current measured in a transformer neutral point grounding
•
Can operate as sensitive tank leakage protection
•
Detects and monitors the circulating current between the neutral points of 2 capacitor banks
•
Switches off high-current faults instantaneously

Structure of the Function

6.12.2
The Overcurrent protection, 1-phase function is used in protection function groups with 1-phase current
measurement. 2 function types are offered:
•
Overcurrent protection, 1-phase – advanced (50N/51N OC-1ph-A)
•
Overcurrent protection, 1-phase – basic (50N/51N OC-1ph-B)
The function type Basic is provided for standard applications. The function type Advanced offers more func-
tionality 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, 1-phase – advanced the following stages can be operated
simultaneously:
•
Maximum of 3 stages Definite-time overcurrent protection (UMZ)
•
1 stage Inverse-time overcurrent protection (AMZ)
•
1 stage User-defined characteristic curve overcurrent protection
•
1 Fast stage
In the function type Overcurrent protection, 1-phase – basic, the following stages can operate simultane-
ously:
•
Maximum of 3 stages Definite-time overcurrent protection
•
1 stage Inverse-time overcurrent protection
The non-preconfigured stages in
characteristic curve, the Definite-time overcurrent protection stage, the Inverse-time overcurrent protec-
tion stage, and the User-defined characteristic curve-time overcurrent protection stage are structured
identically.
The Fast stage uses a fast tripping algorithm. It is therefore suited in particular for sensitive ground-fault
detection according to the high-impedance principle.
522
Figure 6-98 and Figure 6-99 are shown in gray. Apart from the operate-delay
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017