GUID-200BC4CB-8B33-4616-B014-AFCC99ED9224 V2 EN
Figure 276: Time delay for cumulative start
This module also protects the motor from consecutive startups. 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 startup 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 startups occurred, START_CNT.
The value can be reset from the clear menu.
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 startup
counter module.
4.8.5 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.
The full-voltage starting or the direct-on-line starting method is used out of the
many methods used for starting the induction motor. If there is either an electrical
or mechanical constraint, this starting method is not suitable. The full-voltage
1YHT530004D05 D Section 4
Protection functions
615 series 527
Technical Manual
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