Load has dropped or decreased
significantly.
Check for broken parts in the transmission system.
Digital Operator Display Minor Fault Name
UL4
Undertorque Detection 2
Drive output current (or torque in OLV, CLV, AOLV/PM, CLV/PM) less than L6-05 for longer than L6-06
time.
Cause Possible Solutions
Inappropriate parameter settings. Check parameters L6-05 and L6-06.
The load has dropped or decreased
significantly.
Check for broken parts in the transmission system.
Digital Operator Display Minor Fault Name
Uv
Undervoltage
One of the following conditions was true when the drive was stopped and a Run command was entered:
• DC bus voltage dropped below the level specified in L2-05.
• Contactor to suppress inrush current in the drive was opened.
• Low voltage in the control drive input power. This alarm outputs only if L2-01 is not 0 and DC bus voltage
is under L2-05.
Cause Possible Solutions
Phase loss in the drive input power. Check for wiring errors in the main circuit drive input power. Correct the wiring.
Loose wiring in the drive input power
terminals.
• Ensure the terminals have been properly tightened.
• Apply the tightening torque to the terminals as specified. Refer to Wire Gauges and Tightening
Torque on page 58
There is a problem with the drive input
power voltage.
• Check the voltage.
• Lower the voltage of the drive input power so that it is within the limits listed in the specifications.
Drive internal circuitry is 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 your nearest sales representative.
The drive input power transformer is too
small and voltage drops when the power is
switched on.
• Check for an alarm when the magnetic contactor, line breaker, and leakage breaker are closed.
• Check the capacity of the drive input power transformer.
Air inside the drive is too hot. • Check the temperature inside the drive.
The CHARGE light is broken or
disconnected.
Replace either the control board or the entire drive. For instructions on replacing the control board, contact
Yaskawa or your nearest sales representative.
Digital Operator Display Minor Fault Name
voF
Output Voltage Detection Fault
There is a problem with the output voltage.
Cause Possible Solutions
Hardware is damaged.
Replace either the control board or the entire drive. For instructions on replacing the control board, contact
Yaskawa or your nearest sales representative.
<1> Terminals H1, H2, DM+, and DM- on 600 V class models are designed to the functionality, but are not certified to EN61800-5-1, EN954-1/ISO13849
Cat. 3, IEC/EN61508 SIL2, Insulation coordination: class 1.
6.5 Alarm Detection
YASKAWA ELECTRIC SIEP C710616 31B YASKAWA AC Drive – A1000 Technical Manual
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Troubleshooting
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