Motor Restart Inhibit 66, 86
•
Approximate computation of the rotor overtemperature
•
Startup is permitted only if the rotor has sufficient thermal reserves for a complete startup
•
Disabling of the start inhibit is possible if an emergency startup is required.
Load Jam Protection for Motors 51M
•
Protection of motors during sudden rotor blocking
•
Evaluation of the positive sequence system of phase currents
•
Evaluation of the circuit breaker switching state
•
Blocking of function during motor standstill and during motor startup
Frequency Protection 81 O/U
•
Monitoring of falling below (f<) and/or exceeding (f>) with 4 frequency limits and time delays that are
independently adjustable
•
Insensitive to harmonics and abrupt phase angle changes
•
Adjustable undervoltage threshold.
Undervoltage-controlled reactive power protection (27/Q)
•
Detection of critical power system situations
•
Disconnection of power supply facilities from the grid
•
Reconnection under stable power system conditions
Thermal Overload Protection 49
•
Thermal profile of energy losses (overload protection has full memory capability)
•
True r.m.s. calculation
•
Adjustable thermal warning element
•
Adjustable alarm level based on current magnitude
•
Additional time constant setting for motors to accommodate the motor at standstill
•
Integration of ambient temperature or coolant temperature is possible via external temperature sensors
and RTD-Box.
Monitoring Functions
•
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
•
Monitoring of the current transformer and voltage transformer secondary circuits using summation and
symmetry check techniques
•
Trip circuit monitoring possible
•
Phase rotation check.
Ground Fault Detection 50N(s), 51N(s), 67N(s), 59N/64
•
Displacement voltage is measured or calculated from the three phase voltages
•
Determination of a faulty phase on ungrounded or grounded systems
•
Two-element Ground Fault Detection: 50Ns-1 and 50Ns-2
•
High sensitivity (as low as 1 mA)
Introduction
1.3 Characteristics
SIPROTEC 4, 7SJ62/64, Manual 27
C53000-G1140-C207-8, Edition 08.2016
To Next Page
Loading...
Need help?
General
