ABB RELION 620 Series Technical Manual page 768

Section 4
Protection functions
4.10.5
762
GUID-200BC4CB-8B33-4616-B014-AFCC99ED9224 V2 EN
Figure 390: Time delay for cumulative start
This module also protects the motor from consecutive start-ups. When the
LOCK_START output is active, T_RST_ENA shows the possible time for next restart.
The value of T_RST_ENA is calculated by the difference of Restart inhibit time and
the elapsed time from the instant LOCK_START is enabled.
When the ST_EMERG_ENA emergency start is set high, the value of the cumulative
start-up time counter is set to Cumulative time Lim - 60s · Emg start Red rate. This
disables LOCK_START and in turn makes the restart of the motor possible.
This module also calculates the total number of start-ups occurred, START_CNT. The
value can be reset from the Clear menu.
The old Number of motor start-ups occurred counter value (START_CNT) can be
taken into use by writing the value to the Ini start up counter parameter and resetting
the value via the Clear menu from WHMI or LHMI.
The calculated values of T_RST_ENA, T_ST_CNT and START_CNT are available in
the Monitored data view.
The activation of the BLK_LK_ST input signal deactivates the LOCK_START output.
The activation of the BLOCK input signal resets the cumulative start-up counter
module.
Application
When a motor is started, it draws a current well in excess of the motor's full-load rating
throughout the period it takes for the motor to run up to the rated speed. The motor
starting current decreases as the motor speed increases and the value of current
remains close to the rotor-locked value for most of the acceleration period.
1MRS757644 F
620 series
Technical Manual