LED Operator Display
Fault Name
STO
Motor Pull Out or Step Out Detection
Motor pull out or step out has occurred. Motor has exceeded its pull out torque.
Cause
Possible Solution
The wrong motor code has been set (Yaskawa
motors only).
• Enter the correct motor code for the PM being used into E5-01.
• For special-purpose motors, enter the correct data to all E5 parameters according to the Test Report
provided for the motor.
Load is too heavy.
• Increase the value set to n8-55 (Load Inertia for PM).
• Increase the value set to n8-51 (Pull-In Current during Accel/Decel for PM).
• Reduce the load.
• Increase the motor or drive capacity.
Load inertia is too heavy.
Increase n8-55 (Load Inertia for PM).
Acceleration and deceleration times are too
short.
• Increase the acceleration and deceleration times (C1-01 through C1-08).
• Increase the S-curve acceleration and deceleration times (C2-01).
LED Operator Display
Fault Name
UL3
Undertorque Detection 1
The current has fallen below the minimum value set for torque detection (L6-02) for longer than the
allowable time (L6-03).
Cause
Possible Solution
Parameter settings are not appropriate for the
type of load.
Check the settings of parameters L6-02 and L6-03.
There is a fault on the machine side.
Check the load for any problems.
LED Operator Display
Fault Name
UL4
Undertorque Detection 2
The current has fallen below the minimum value set for torque detection (L6-05) for longer than the
allowable time (L6-06).
Cause
Possible Solution
Parameter settings are not appropriate for the
type of load.
Check the settings of parameters L6-05 and L6-06.
There is a fault on the machine side.
Check the load for any problems.
LED Operator Display
Fault Name
UL5
Mechanical Weakening Detection 2
The operation conditions matched the conditions set to L6-08.
Cause
Possible Solution
Undertorque was detected and matched the
condition of mechanical loss detection
operation selection (L6-08).
Check the load side for any problems.
LED Operator Display
Fault Name
Uv1
DC Bus Undervoltage
One of the following conditions occurred while the drive was stopped:
• Voltage in the DC bus fell below the undervoltage detection level (L2-05).
• For 200 V class: approximately 190 V (160 V for single phase drives)
• For 400 V class: approximately 380 V (350 V when E1-01 is less than 400) The fault is output only
if L2-01 = 0 or L2-01 = 1 and the DC bus voltage is under L2-05 for longer than 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 46
There is a problem with the voltage from the
drive input power.
• Check the voltage.
• Correct the voltage to within range listed in drive input power specifications.
The power has been interrupted.
Correct the drive input power.
Drive internal circuitry has become worn.
• Check the maintenance time for the capacitors (U4-05).
• Replace the drive if U4-05 exceeds 90%.
The drive input power transformer is not large
enough and voltage drops after switching on
power.
Check the capacity of the drive input power transformer.
Air inside the drive is too hot.
Check the drive internal temperature.
Problem with the CHARGE indicator.
Replace the drive.
LED Operator Display
Fault Name
Uv2
Control Power Supply Voltage Fault
Voltage is too low for the control drive input power.
Cause
Possible Solution
L2-02 changed from its default value in drive
that is 7.5 kW or smaller without installing a
Momentary Power Loss Ride-Thru.
Correct parameter L2-02 setting or install optional Momentary Power Loss Ride-Thru unit.
The wiring for the control power supply is
damaged.
• Cycle power to the drive. Check if the fault reoccurs.
• Replace the drive if the fault continues to occur.
Internal circuitry is damaged.
• Cycle power to the drive. Check if the fault reoccurs.
• Replace the drive if the fault continues to occur.
6.4 Fault Detection
SIEP C710606 20 OYMC AC Drive - V1000 User Manual
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Troubleshooting
7/16/2008-13:23