ABB 615 series Technical Manual page 757

1MAC059074-MB A
615 series ANSI
Technical Manual
GUID-35DD1223-14B2-48BF-ADF4-4A1DF6930314 V1 EN
Figure 376: Functional module diagram
Startup supervisor
This module detects the starting of the motor. The starting and stalling motor conditions
are detected in four different modes of operation. This is done through the Operation mode
setting.
When the Operation mode setting is operated in the "IIt" mode, the function calculates the
value of the thermal stress of the motor during the start-up condition. In this mode, the
start-up condition is detected by monitoring the TRMS currents.
The Operation mode setting in the "IIt, CB" mode enables the function to calculate the
value of the thermal stress when a start-up is monitored in addition to the CB_CLOSED
input.
In the "IIt & stall" mode, the function calculates the thermal stress of the motor during the
start-up condition. The start-up condition is detected by monitoring the TRMS currents.
In the "IIt & stall, CB" mode, the function calculates the thermal stress of the motor during
the start-up condition but the start-up condition is detected by monitoring the TRMS
current as well as the circuit breaker status.
In both the "IIt & stall" and "IIt & stall, CB" mode, the function also checks for motor
stalling by monitoring the speed switch.
When the measured current value is used for start-up supervision in the "IIt" and "IIt &
stall" modes, the module initially recognizes the de-energized condition of the motor
when the values of all three phase currents are less than Motor standstill A for longer than
100 milliseconds. If any of the phase currents of the de-energized condition rises to a value
Section 4
Protection functions
751