Siemens SIPROTEC 4 7SJ61 Manual page 24

Introduction
1.3 Characteristics
Monitoring Functions
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Reliability of the device is greatly increased because of self-monitoring of the internal measurement
circuits, the auxiliary power supply as well as the hardware and software
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Supervision of the current transformer secondary circuits by means of sum and symmetry checks
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Trip circuit monitoring possible
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Phase rotation check.
Ground Fault Detection 50N(s), 51N(s), 67N(s), 59N/64
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Two-element Ground Fault Detection: 50Ns-1 and 50Ns-2
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High sensitivity (as low as 1 mA)
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Overcurrent element with definite time or inverse time delay
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For inverse time overcurrent protection, characteristics according to IEC or ANSI standards, one userde-
fined and two logarithmic inverse current/time characteristics are available
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Optionally applicable as additional ground fault protection.
Intermittent Ground Fault Protection
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Detects and accumulates intermittent ground faults
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Tripping after configurable total time.
Automatic Reclosing 79
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Single-shot or multi-shot
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With separate dead times for the first and all succeeding shots
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Protective elements that initiate automatic reclosing are selectable. The choices can be different for
phase faults and ground faults
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Separate programs for phase and ground faults
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Interaction to time overcurrent protection element and ground fault elements. They can be blocked in
dependence of the reclosing cycle or released instantaneously
Breaker Failure Protection 50 BF
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By checking the current and/or evaluating the circuit breaker auxiliary contacts
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Started by any integrated protection function that trips
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Initiation possible via a binary input from an external protective device.
Flexible Protective Functions
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Up to 20 customizable protection functions with three-phase or single-phase operation
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Any calculated or directly measured quantity can be evaluated on principle
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Standard protection logic with definite time characteristic
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Internal and configurable pickup and dropout delay
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Modifiable message texts.
RTD box
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Detection of any ambient temperatures or coolant temperatures by means of an external RTD box and
external temperature sensors.
24 SIPROTEC 4, 7SJ61, Manual
C53000-G1140-C210-6, Edition 05.2016