YASKAWA A1000 Series Quick Start Manual page 191

Cause
Deceleration time is too short and regenerative
energy is flowing from the motor into the drive
Fast acceleration time causes the motor to
overshoot the speed reference
Excessive braking load
Surge voltage entering from the drive input
power
Ground fault in the output circuit causes the
DC bus capacitor to overcharge
Improper parameters related to Speed Search
(including Speed Search after a momentary
power loss and after a fault restart)
Drive input power voltage is too high
The braking transistor or braking resistor are
wired incorrectly
PG cable is disconnected
PG cable wiring is wrong
Electrical signal interference along the PG
encoder wiring
Drive fails to operate properly due to electrical
signal interference
Load inertia is set incorrectly
Braking function is being used in OLV/PM
Motor hunting occurs
YASKAWA ELECTRIC TOEP C710616 41G YASKAWA AC Drive - A1000 Quick Start Guide
Overvoltage
Voltage in the DC bus has exceeded the overvoltage detection level.
ov
• For 200 V class drives: approximately 410 V
• For 400 V class drives: approximately 820 V (740 V when E1-01 is less than 400)
• For 600 V class drives: approximately 1040 V
• Increase the deceleration time (C1-02, C1-04, C1-06, C1-08).
• Install a dynamic braking resistor or a dynamic braking resistor unit.
• Set L3-04 to 1 to enable stall prevention during deceleration. Stall Prevention is enabled as the default
setting.
• Check if sudden drive acceleration triggers an overvoltage alarm.
• Increase the acceleration time.
• Use longer S-curve acceleration and deceleration times.
• Enable the Overvoltage Suppression function (L3-11 = 1).
• Lengthen the S-curve at acceleration end.
The braking torque was too high, causing regenerative energy to charge the DC bus. Reduce the braking
torque, use a dynamic braking option, or lengthen decel time.
Install a DC link choke.
Note: Voltage surge can result from a thyristor convertor and phase advancing capacitor using
the same input power supply.
• Check the motor wiring for ground faults.
• Correct grounding shorts and reapply power.
• Check the settings for Speed Search-related parameters.
• Enable Speed Search restart function (b3-19 greater than or equal to 1, up to 10).
• Adjust the current level during Speed Search and the deceleration time (b3-02 and b3-03 respectively).
• Perform Stationary Auto-Tuning for line-to-line resistance and then set b3-14 to 1 to enable Speed
Estimation Speed Search.
• Check the voltage.
• Lower drive input power voltage within the limits listed in the specifications.
• Check braking transistor and braking resistor wiring for errors.
• Properly rewire the braking resistor device.
Reconnect the cable.
Correct the wiring.
Separate the wiring from the source of the electrical signal interference. Often, the source is the output
lines from the drive.
• Review the list of possible solutions provided for controlling electrical signal interference.
• Review the section on handling electrical signal interference and check the control circuit lines, main
circuit lines, and ground wiring.
• Check the load inertia settings when using KEB, overvoltage suppression, or Stall Prevention during
deceleration.
• Adjust the load inertia ratio in L3-25 to better match the load.
Connect a braking resistor.
• Adjust the parameters that control hunting.
• Set the gain for Hunting Prevention (n1-02).
• Adjust the AFR time constant (n2-02 and n2-03).
• Adjust the speed feedback detection suppression gain for PM motors (n8-45) and the time constant for
pull-in current (n8-47).
Possible Solution
5.2 Fault Detection
5
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