The activation of the
BLOCK
input signal resets the thermal stress calculator and
deactivates the
OPR_IIT
output.
Stall protection
This module is activated only when the selected
Operation mode
setting value is "IIt &
stall" or "IIt & stall, CB".
The start-up current is specific to each motor and depends on the start-up method used,
such as direct online, autotransformer and rotor resistance insertion. The start-up time is
dependent on the load connected to the motor.
Based on the motor characteristics supplied by the manufacturer, this module is required
if the stalling time is shorter than or too close to the starting time. In such cases, a speed
switch must be used to indicate whether a motor is accelerating during start-up or not.
At motor standstill, the
STALL_IND
input is active. It indicates that the rotor is not
rotating. When the motor is started, at certain revolution the deactivation of the
STALL_IND
by the speed switch indicates that the rotor is rotating. If the input is not
deactivated within
Lock rotor time
, the
OPR_STALL
output is activated.
The module calculates the duration of the motor in stalling condition, the
STALL_RL
output indicating the percent ratio of the start situation and the set value of
Lock rotor
time
. The value is available in the Monitored data view.
The activation of the
BLOCK
input signal resets the operation time and deactivates the
OPR_STALL
output.
Cumulative start-up protection
This module protects the motor from an excessive number of start-ups.
Whenever the motor is started, the latest value of
START_TIME
is added to the existing
value of
T_ST_CNT
and the updated cumulative start-up time is available at
T_ST_CNT
.
If the value of
T_ST_CNT
is greater than the value of
Cumulative time Lim
, the
LOCK_START
output is activated and lockout condition for the restart of motor is enabled
during the time the output is active. The
LOCK_START
output remains high until the
T_ST_CNT
value reduces to a value less than the value of
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
.
1MAC059074-MB A
Section 4
Protection functions
615 series ANSI
755
Technical Manual
Summary of Contents for Relion 615 series
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