YASKAWA A1000

6.4 Fault Detection
348 YASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual
Digital Operator Display Fault Name
SC
Output Short-Circuit or IGBT Fault
Sho
rt Circuit or Ground Fault is detected
Note: Fault reset will not be received to prevent a short-circuit of the internal circuitry caused by the IGBP fault.
Cause Possible Solution
Motor has been damaged from
overheat or the motor
insulation has been weakened.
Check the motor insulation resistance and replace the motor if continuity is detected.
The cable is damaged and is coming into contact with
something causing a short-circuit.
Check the motor power cable. Repair any short-circuits.
Hardware fault.
A short-circuit or grounding fault on the drive outp
ut side has damaged the output transistors.
Make sure drive output is not shorted as follows:
B1 
U, V, W
– (negative) 
U, V, W
The above short-circuit will dam
age the output transistors.
Contact your YASKAWA representative or our sales offices for assistance.
Digital Operator Display Fault Name
SEr
Too Many Speed Search Restarts
Th
e number of Speed Search restarts exceeded the number set to b3-19.
Cause Possible Solution
Speed Search parameters are set to the wrong values.
• Reduce the detection compensation gai
n during Speed Search (b3-10).
• Increase the current level when at
tempting Speed Search (b3-17).
• Increase the detection time duri
ng Speed Search (b3-18).
• Repeat Auto-Tuning.
The motor is coasting in the opposite direction of the
Run command.
Enable Bi-Directional Speed Search (b3-14 = 1).
Digital Operator Display Fault Name
STo
Motor Pull Out or Step Out Detection
M
otor pull out or step out has occurred. Motor has exceeded its pull-out torque.
Cause Possible Solution
The wrong motor code is 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 load inertia for PM motor (n8-55
).
• Increase the pull-in current d
uring accel/decel (n8-51).
• Reduce the load.
• Increase the motor or drive capacity.
Load inertia is too heavy. Increase the
load inertia for PM motor (n8-55).
Acceleration and deceleration times are too short.
• Increase the acceleration and decelerati
on times (C1-01 through C1-08).
• Increase the S-curve acceleration and deceleration times (C2-01).
Speed response is too slow. Increase the load inertia for PM motor (n8-55).
Digital Operator Display Fault Name
SvE
Zero Servo Fault
Pos
ition deviation during zero servo.
Cause Possible Solution
Torque limit is set too low. Set the torque limit to an appropriate value using parameters L7-01 to L7-04.
Excessive load torque. Reduce the amount of load torque.
Electrical signal interference along PG encoder wiring. Check the PG signal for electrical signal interference.
Digital Operator Display Fault Name
<2>
THo
Thermistor Disconnect
The
thermistor used to detect motor temperature has become disconnected.
Cause Possible Solution
The motor thermistor is not connected properly. Check the wiring for the thermistor.
Digital Operator Display Fault Name
UL3
Undertorque Detection 1
Th
e 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 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.
Digital Operator Display Fault Name
UL4
Undertorque Detection 2
Th
e 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 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.
Digital Operator Display Fault Name
UL5
Mechanical Weakening Detection 2
Th
e operation conditions matched the conditions set to L6-08.
Cause Possible Solution
Undertorque was detected and m
atched the conditions
for mechanical loss detection set to L6-08.
Check the load side for any problems.