7SR210 & 7SR220 Description of Operation
Unrestricted ©2018 Siemens Protection Devices Limited Page 85 of 94
5.9.2 Load Blinder (21) Single-Phase.
Single-phase mode uses the normal impedance (Z) of each phase. The overcurrent blocking is phase segregated
and is dependent on the individual overcurrent settings per phase. Only the under-voltage threshold (Blinder V <
block) can block the function.
Distributed generation can cause power flow in reverse direction to normal system operation. Load Impedance
Blinders are used to block overcurrent operation for loads above a particular level and angle.
A Blinder is an impedance sensing element with a straight-line characteristic when plotted on the R – X plane
Figure 5.9.2-1 Logic Diagram: Load Blinder Single-Phase
To Next Page
Loading...
