4-164
07- 13
Low Voltage Detection Level
Range
【
200V】: 150~300V
【
400V】: 300~600V
07- 25
Low voltage Detection Time
Range 【0.00~1.00】Sec
Adjust the 07-13 voltage level from 150 to 300 Vdc (200V class) or from 300 to 600 Vdc (400V class).
When the AC input voltage is lower than the 07-13 value (07-13/ 1.414 = AC voltage detection level) for
the time specified in 07-25 the low-voltage error "UV" will displayed. If 07-25 = 0.00 sec., the UV error will
be displayed immediately.
Set preventive measures:
- The inverter input voltage will limit the output voltage. If the input voltage drops excessively, or if the
load is too big, the motor may stall.
- If the input voltage drops below the value set in 07-13 then the output is turned off momentarily. The
inverter will not automatically start when power is restored.
07- 14
Pre-excitation Time
Range
【
0.00~10.00】Sec
07- 15
Pre-excitation Level
Range
【
50~200】%
If a high starting torque is required for the application, especially for a large horsepower motors, the
pre-excitation operation can be used to pre-flux (magnetize) the motor.
07-14: Pre-excitation time
When an operation command (forward or reverse) is activated, the inverter will automatically start
pre-excitation based on the time set in parameter 07-14.
The time for the flux to reach 100% is a function value of motor’s electrical time constant (See figure
4.4.52).
Electrical time constant (quadratic by-pass circuit time constant) is suggested to set 2.00~4.00 Sec.
07-15: Pre-excitation initial level
Use the pre-excitation initial level (07-15) to provide a higher excitation current during the pre-excitation
time (07-14), which will increase the speed and stability for motors.
In order to quickly magnetize the motor, reduce the pre-excitation time (07-14) and set the pre-excitation
level (07-15) to a high level.
If 07-15 is set greater than 100%, providing a high excitation current during the pre-excitation time (07-14),
motor’s magnetization time is shorted. When the setting reaches 200%, magnetization is reduced by
roughly half.
A high pre-excitation level (07-15) might result in excessive motor sound during pre-excitation.
When the flux reaches 100%, pre-excitation current reverts back to 100% and pre-excitation is completed.
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