Siemens siprotec SJ62 User Manual page 32

Motor Starting Pro-
tection 48
Motor Start Inhibit
66, 86
Frequency Protec-
tion 81 O/U
Thermal Overload
Protection 49
Monitoring Func-
tions
Ground Fault De-
tection 50N(s),
51N(s), 67N(s),
59N/64
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
• Inverse time tripping characteristic based on an evaluation of the motor starting cur-
rent;
• Definite time delay for blocked rotor.
• Approximate replica of excessive rotor temperature;
• 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.
• Monitoring on undershooting (f<) and/or overshooting (f>) with 4 frequency limits
and delay times that are independently adjustable;
• Insensitive to harmonics and abrupt phase angle changes;
• Adjustable undervoltage threshold.
• Thermal profile of energy losses (overload protection has total memory capability);
• True r.m.s. calculation;
• Adjustable thermal alarm level;
• 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.
• Availability of the device is greatly increased because of self-monitoring of the inter-
nal measurement circuits, power supply, hardware, and software;
• Current transformer and voltage transformer secondary circuits are monitored
using summation and symmetry check techniques
• Trip circuit monitoring;
• Phase rotation check.
• Displacement voltage is measured or calculated from the three phase voltages;
• Determination of a faulty phase on ungrounded or grounded networks;
• Two-element Ground Fault Detection: 50Ns-1 and 50Ns-2;
• High sensitivity (as low as 1 mA);
• Overcurrent element with definite time or inverse time delay;
• One user-defined and two logarithmic-inverse current/time curves are available for
inverse time O/C protection;
• Direction determination with zero-sequence quantities (I
fault direction determination;
• Any element can be set as directional or non-directional — forward sensing direc-
tional, or reverse sensing directional;
• Directional characteristic can be adjustable;
• Optionally applicable as additional ground fault protection.
1.3 Characteristics
, V ), wattmetric ground
0 0
30