YASKAWA Z1000 User Manual page 211

Digital Operator Display
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
Drive fails to operate properly due to noise
interference
Load inertia is set incorrectly
Motor hunting occurs
HOA Keypad Display
ov2
Cause
The wiring is too long
YASKAWA TOEP YAIZ1U 03B YASKAWA AC Drive – Z1000 User Manual
Overvoltage
ov
Voltage in the DC bus has exceeded the overvoltage detection level.
• For 600 V class drives: approximately 1040 V
• Increase the deceleration time (C1-02 and C1-04).
• 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 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.
• Review the list of possible solutions provided for controlling noise.
• Review the section on handling noise interference on page
circuit lines, and ground wiring.
• Review the section on handling noise 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.
• Adjust the parameters that control hunting.
• Set the gain for Hunting Prevention (n1-02).
• Adjust the AFR time constant (n2-02 and n2-03).
Overvoltage 2
Bus voltage is boosted because the motor cable is too long.
• Shorten the shielded motor cable
• Lower the carrier frequency
• Switch on the internal EMC filter if the power supply has a neutral ground
Fault Name
Possible Solution
240 and check the control circuit lines, main
Fault Name
Possible Solution
5.4 Fault Detection
5
211