HOA Keypad Display
Fault Name
Uv1
DC Bus Undervoltage
Voltage in the DC bus fell below the undervoltage detection level (L2-05).
• For 208 V: approximately 190 V
• For 480 V: approximately 440 V
The fault is output only if L2-01 is set to 0 or 1 and the DC bus voltage has fallen below the level set
to L2-05 for longer than the time set to L2-02
.
Cause
Possible Solution
Input power phase loss
• The main circuit drive input power is wired incorrectly.
• Correct the wiring.
One of the drive input power wiring terminals is
loose
• Ensure there are no loose terminals.
• Apply the tightening torque specified in this manual to fasten the terminals.
and Tightening Torque Specifications on page 62
There is a problem with the voltage from the drive
input power
• Check the voltage.
• Correct the voltage to be within the range listed in drive input power specifications.
• If there is no problem with the power supply to the main circuit, check for problems with the main
circuit magnetic contactor.
The power has been interrupted
Correct the drive input power.
The main circuit capacitors are worn
• Check the maintenance time for the capacitors (U4-05).
• Replace either the control board or the entire drive if U4-05 exceeds 90%. For instructions on
replacing the control board, contact Yaskawa or a Yaskawa representative.
The relay or contactor on the soft-charge bypass
circuit is damaged
• Cycle power to the drive and see if the fault reoccurs.
• If the problem continues, replace either the control board or the entire drive. For instructions on
replacing the control board, contact Yaskawa or a Yaskawa representative.
• Check monitor U4-06 for the performance life of the soft-charge bypass.
• Replace either the control board or the entire drive if U4-06 exceeds 90%. For instructions on
replacing the control board, contact Yaskawa or a Yaskawa representative.
HOA Keypad Display
Fault Name
Uv2
Control Power Supply Voltage Fault
Voltage is too low for the control drive input power.
Cause
Possible Solution
Internal circuitry is damaged
• Cycle power to the drive. Check if the fault reoccurs.
• If the problem continues, replace either the control board or the entire drive. For instructions on
replacing the control board, contact Yaskawa or a Yaskawa representative.
HOA Keypad Display
Fault Name
Uv3
Undervoltage 3 (Soft-Charge Circuit Fault)
The soft-charge bypass circuit failed.
Cause
Possible Solution
The relay or contactor on the soft-charge bypass
circuit is damaged
• Cycle power to the drive and see if the fault reoccurs.
• If the problem continues, replace either the control board or the entire drive. For instructions on
replacing the control board, contact Yaskawa or a Yaskawa representative.
• Check monitor U4-06 for the performance life of the soft-charge bypass.
• Replace either the control board or the entire drive if U4-06 exceeds 90%. For instructions on
replacing the control board, contact Yaskawa or a Yaskawa representative.
HOA Keypad Display
Fault Name
voF
Output Voltage Detection Fault
Problem detected with the voltage on the output side of the drive.
Cause
Possible Solution
Hardware is damaged
Replace the control board or the entire drive. For instructions on replacing the control board, contact
Yaskawa or a Yaskawa representative.
6.4 Fault Detection
YASKAWA ELECTRIC SIEP YAIZ1B 01E YASKAWA AC Drive – Z1000 Bypass Technical Manual
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Diagnostics & Troubleshooting