Cumulative time Lim. The start time counter reduces at the rate of the value of
Counter Red rate.
The
LOCK_START
output becomes activated at the start of
MOT_START
. The output
remains active for a period of
Restart inhibit time.
Figure 617: 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.
4.10.6
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
1MRS759142 F
Protection functions
REX640
Technical Manual
1099