6.4 Fault Detection
YASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual 349
Digital Operator Display Fault Name
<2>
UnbC
Current Unbalance
C
urrent flow has become unbalanced.
Cause Possible Solution
The internal current sensor has detected a current
unbalance si
tuation.
• Check wiring.
• Check for damaged transistors.
• Check for short circuits or grounding problems on the connected motor.
Digital Operator Display Fault Name
Uv1
DC Bus Undervoltage
One of t
he following conditions occurred while the drive was running:
• Voltage in the DC bus fell below the u
ndervoltage detection level (L2-05)
• For 200 V class: approximately 190 V
• For 400 V class: approximately 380 V (350 V when E1-01 is less th
an 400) The fault is output only if L2-01 = 0 or L2-01 = 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. Refer to Wire Gauges and
Tightening Torque on
page 76
There is a problem with the voltage from the drive input
power
.
• Check the voltage.
• Correct the voltage to be within the range lis
ted 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 m
ain circuit capacitors are worn.
• Check the maintenance time for th
e capacitors (U4-05).
• Replace either the control board or the enti
re drive if U4-05 exceeds 90%. For instructions on replacing the control board,
contact YASKAWA or your nearest sales representative.
The relay or contactor on the soft-char
ge 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 ent
ire drive. For instructions on replacing the control board,
contact YASKAWA or your nearest sales representative.
• Check monitor U4-06 for the performance l
ife 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 your nearest sales representative.
Digital Operator Display Fault Name
Uv2
Control Power Supply Voltage Fault
V
oltage is too low for the control drive input power.
Cause Possible Solution
For models CIMR-A2A000
4 through 2A0056 and
CIMR-A4A0002 through 4A0031: L2-02 was
changed from its default value without installing a
Momentary Power Loss Ride-Thru unit.
Correct the setting to L2-02 or install an optional Momentary Power Loss Ride-Thru unit.
Control power supply wiring is damaged.
• Cycle power to the drive. Check if the fault reoccurs.
• If the problem continues, replace the control board, t
he entire drive, or the control power supply.
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 your nearest sales representative.
Digital Operator Display Fault Name
Uv3
Undervoltage 3 (Soft-Charge By
pass Circuit Fault)
The soft-charge bypass circuit has failed.
Cause Possible Solution
The relay or contactor on the soft-char
ge 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 ent
ire drive. For instructions on replacing the control board,
contact YASKAWA or your nearest sales representative.
• Check monitor U4-06 for the performance l
ife 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 your nearest sales representative.
Digital Operator Display Fault Name
<2>
Uv4
Gate Drive Board Undervoltage
V
oltage drop in the gate drive board circuit.
Cause Possible Solution
Not enough power is being supplied to the gate drive
board.
• Cycle power to the drive and
see if the fault reoccurs. Refer to Diagnosing and Resetting Faults on page 366.
• If the problem continues, replace either the gate drive board or the entire drive. For instructions on replacing the gate board,
contact YASKAWA or a YASKAWA representative.
Digital Operator 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.
Re
place either the control board or the entire drive. For instructions on replacing the control board, contact YASKAWA or your
nearest sales representative.
<1> Displayed as or when occurring at drive power up. When one of the faults occurs after successfully starting the drive, the
display will show or .
<2> Occurs in models CIMR-A4A0930 and 4A1200.
<3> This function prevents continuous operation in reverse when using high frequency injection (n8-57 = 1) in the Advanced Open Loop Vector
Control mode for PM motors (A1-02 = 6) with a motor for which no motor code has been entered (it does not simply prevent reverse
operation). To quickly detect undesirable reverse operation, set L8-93, L8-94, and L8-95 to low values within range of erroneous detection.
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