6
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Lowering
In the same way as for lifting, when the torque decreases, the analog signals corresponding to the load size are
input as torque compensation signals from before the Inverter starts until operation stops. (Factory setting: 10
V/100% torque)
Negative polarity is input for motor loads and positive polarity is input for regenerative loads.
The following diagram shows the time chart for lowering.
Fig 6.86 Torque Compensation Time Chart (Lowering)
Analog Input Filter Time Constant
If noise enters the analog frequency reference during operation using analog frequency reference (b1-01 = 1),
and operation becomes rough, implement noise countermeasures and also set H3-12 (Analog input filter time
constant) to between 0.01 and 0.10 s.
Confirming Startup Current and Reducing Carrier Frequency
When performing trial operation, check the motor current using the Digital Operator or a clamp ammeter with
and without a mechanical load. An extremely large current will flow if the motor torque at start is insufficient,
or if timing is not correct and the motor locks with the holding brake.
For applications with repetitive loads (cranes, elevators, presses, washing machines, etc.), if a current exceed-
ing 125% of the Inverter rated current or more flows repeatedly, the IGBT in the Inverter will be subject to
heat stress, resulting in a shortened life span. In this case, select CT instead of VT and reduce the load,
lengthen the acceleration/deceleration time, or increase the frame size of the Inverter so that the peak current
for repetitive operation will drop to less than 125% of the Inverter rated current. If performing a trial operation
with repetitive loads, make sure that the peak current for repetitive operation is less than 125% of the Inverter
rated current. If particularly low noise is not required, do not increase the Inverter’s carrier frequency to
reduce the influence of heat stress.
IMPORTANT
1. For either increasing or decreasing torque, externally maintain the torque compensation signals during
operation to prevent them from fluctuating. Fluctuation in compensation signals during operation may result
in vibration.
2. If reverse run is used for lifting and forward run is used for lowering, the torque compensation signal polar-
ity must be reversed.
OFF
OFF
ON
DOWN (Forward)
ON
HIGH/LOW
Output frequency
0
Motor torque
0
OFF
ON
During run 2
OPEN
Holding brake operation
CLOSE
(Regenerative load: Inputs positive polarity.)
(Motor load: Inputs negative polarity.)
t
(Regenerative load)
(Motor load)
Analog signals corresponding to load size
Same as above
Torque compensation
signal: 0
