Yaskawa Z1000 AC Drive HVAC - Manual (Page 207)

Excessive braking load
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.
Surge voltage entering from the drive input
power
Install a DC link choke.
Note: Voltage surge can result from a thyristor convertor and phase advancing capacitor using
the same input power supply.
Ground fault in the output circuit causes the
DC bus capacitor to overcharge
• Check the motor wiring for ground faults.
• Correct grounding shorts and reapply power.
Improper parameters related to Speed Search
(including Speed Search after a momentary
power loss and after a fault restart)
• 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.
Drive input power voltage is too high
• Check the voltage.
• Lower drive input power voltage within the limits listed in the specifications.
The braking transistor or braking resistor are
wired incorrectly
• Check braking transistor and braking resistor wiring for errors.
• Properly rewire the braking resistor device.
Drive fails to operate properly due to noise
interference
• Review the list of possible solutions provided for controlling noise.
• Review the section on handling noise interference on page
233 and check the control circuit lines, main
circuit lines, and ground wiring.
• Review the section on handling noise interference and check the control circuit lines, main circuit lines,
and ground wiring.
Load inertia is set incorrectly
• 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.
Motor hunting occurs
• Adjust the parameters that control hunting.
• Set the gain for Hunting Prevention (n1-02).
• Adjust the AFR time constant (n2-02 and n2-03).
HOA Keypad Display Fault Name
ov2
Overvoltage 2
Bus voltage is boosted because the motor cable is too long.
Cause Possible Solution
The wiring 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
Digital Operator Display Fault Name
PF
Input Phase Loss
Drive input power has an open phase or has a large imbalance of voltage between phases. Detected when
L8-05 is set 1 (enabled).
Cause Possible Solution
There is phase loss in the drive input power
• Check for wiring errors in the main circuit drive input power.
• Correct the wiring.
There is loose wiring in the drive input power
terminals
• Ensure the terminals are tightened properly.
• Apply the tightening torque as specified in this manual.
Refer to Main Circuit Wire Gauges and
Tightening Torque on page 81 for details.
There is excessive fluctuation in the drive
input power voltage
• Check the voltage from the drive input power.
• Review the possible solutions for stabilizing the drive input power.
There is poor balance between voltage phases Stabilize drive input power or disable phase loss detection.
The main circuit capacitors are worn
• Check the maintenance time for the capacitors (U4-05).
• Replace the main capacitor(s) if U4-05 is greater than 90%. For instructions on replacing the
capacitor(s), contact Yaskawa or a Yaskawa representative.
Check for problems with the drive input power. If drive input power appears normal but the alarm
continues to occur, replace either the control board or the entire drive. For instructions on replacing the
control board, contact Yaskawa or a Yaskawa representative.
5.4 Fault Detection
YASKAWA ELECTRIC TOEP YAIZ1U 03A YASKAWA AC Drive – Z1000 User Manual 207
5
Troubleshooting