Hitachi CONVENTION 14 Instruction Manual page 130

Miscellaneous Settings (continued)
B140: Over-current Trip Suppression – The
Over-current
monitors the motor current and actively
changes the output frequency profile to
maintain the motor current within the limits.
Although "LAD"
acceleration / deceleration", the inverter only
"STOPs" the acceleration and deceleration
ramp so that it will not cause an over-
current trip event.
The graph at right shows an inverter output
profile that starts acceleration to a constant
speed. At two different points during the
acceleration, motor current increases and
exceeds the fixed level of Over-current Trip
Suppression level.
When the Over-current Trip Suppression feature is enabled by B140 = 01, the inverter
stops the acceleration ramp in each case until the motor current level is again less than
the threshold value, which is approximately 150% of the rated current of the inverter.
When using the Over-current Trip Suppression feature, please note the following:
When the feature is enabled (B140 = 01), the actual acceleration may be longer
than the value set by parameters F002/F202 in some cases.
The Over-current Trip Suppression feature does not operate by maintaining a
constant motor current. So it is still possible to have an over-current trip event
during extreme acceleration.
B150: Carrier Mode – When the Carrier Mode is enabled (B150 = 01), the inverter
detects the motor current and automatically reduces the carrier frequency when it rises
up to a certain level.
B151: Selection of Ready function – When the Ready function is enabled (B151 = 01),
then the inverter outputs devices are ON even when the motor is stopped. Keeping all
the internal power output components energized allows the idle time between the RUN
command and actual PWM output to be shortened.
HIGH VOLTAGE: When set RDY function ON, there will be a voltage appearing at
motor output terminals U, V and W even if the motor is in stop mode. Never touch the
inverter power terminal when the inverter is powered up.
Trip Suppression function
refers to
B140 = 01 OC LADSTOP = Enabled
Motor
current
"linear
0
Output
frequency
0
Set acc time (F002)
Approx. 150% of the inverter
rated current
Stops accel
Resumes accel
Actual acc time
3 − 47
3 47
t
t