SIPROTEC easy 7SJ45
Numerical overcurrent protection relay powered by CTs
Description
The SIPROTEC easy 7SJ45 is a numerical overcurrent protection relay which is primarily intended as a radial feeder or transformer protection (backup) in electrical networks. It provides definite-time and inverse-time overcurrent protection according to IEC and ANSI standards. The 7SJ45 relay does not require auxiliary voltage supply. It imports its power supply from the current transformers.
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Function overview
Functions
Operation without auxiliary voltage via integrated CT power supply
Standard current transformers (1 A/ 5 A)
Low power consumption: 1.4 VA at
N
(of the relay)
Easy mounting due to compact housing
Easy connection via screw-type terminals
Protection functions
2-stage overcurrent protection
Definite-time and inverse-time characteristics (IEC/ANSI)
High-current stage
I
>> or calculated earth-current stage
IE
> or
IEp
> selectable
Trip with pulse output (24 V DC / 0,1 Ws) or relay output (change over contact)
Repetition of trip during circuit-breaker failure (relays with pulse output)
Combination with electromechanical relays is possible due to the emulation algorithm
Front design
Simple setting via DIP switches (self-explaining)
Settings can be executed without auxiliary voltage - no PC
Integrated mechanical trip indication optionally