Introduction
1-97SJ62 Manual
C53000-G1140-C121-1
• Two ground fault elements 67Ns-1 and 67Ns-2 that can be set as non-directional,
forward sensing directional, or reverse sensing directional;
• Fault direction is determined by calculating the zero sequence real power or reac-
tive power, as determined by a setting;
• Directional characteristics of 67Ns-1 and 67Ns-2 are adjustable;
• Phase current stabilization is included to accommodate current transformers satu-
ration.
Negative Sequence
Current Protection
• Two definite-time elements 46-1 and 46-2 and one inverse-time element 46-TOC;
• Common U.S. ANSI time-characteristics or IEC characteristics are available for 46-
TOC.
Starting Time
Monitoring for
Motors
• Current dependent tripping based on an evaluation of the motor starting current.
• Blocked rotor protection.
Thermal Overload
Protection
• Temperature rise of the protected equipment is calculated using a thermal homo-
geneous-body model that takes into account energy entering the equipment and
energy losses. Thermal overload protection has full memory capability;
• Adjustable warning levels based on temperature rise and current magnitude;
• Additional time constant setting for motors to accommodate both the motor rotating
and the motor at standstill.
Start Inhibit
for Motors
• Rotor temperature is calculated based on the stator currents;
• Start-up is permitted only if the rotor has sufficient thermal reserves for a complete
start-up;
• Disabling of the start inhibit is possible if an emergency start-up is required.
Voltage Protection • Two undervoltage elements 27-1 and 27-2 measuring positive sequence voltage;
• Choice of current supervision for 27-1 and 27-2;
• Adjustable dropout voltage for 27-1;
• Separate overvoltage protection 59-1.
Frequency
Protection
• Four elements that are independently adjustable for function - underfrequency or
overfrequency, pickup, and time delay;
• Insensitive to harmonics and abrupt phase angle changes;
• Adjustable undervoltage blocking.
Breaker Failure
Protection
• Breaker failure condition determined by current flow after a trip signal has been is-
sued. As an option, the breaker position indication (binary input) can be evaluated;
• Breaker failure protection initiated by the tripping of any integrated protective ele-
ment that trips the circuit breaker (internal start);
• Initiation possible through a binary input from an external protective device (exter-
nal start);
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