9. Troubleshooting and Maintenance
9-9
③ Connect inverter panel grounding connected with motor grounding to the building grounding.
☞ If not, incorrect motor speed may be input due to encoder input noise.
④ Is too large speed gain assigned to the inverter while motor load is light?
☞ Motor oscillates at stop when PI gain is set much larger than the actual load in CON_03 and CON_04.
Therefore, gain should be set accordingly. Responsiveness increases when P gain is set higher and I lower but
system may become unstable. Gain value varies system but generally set 30 ~ 70% for P gain and set
100 ~ 500ms for I gain.
⑤ Increase PAR_13 Enc LPF setting value.
⑥ Is there slip present at the connection of encoder and motor shaft?
☞ Poor encoder and motor connection may generate slip. Check the connection is tight.
12) Parameter change is not saved.
☞ Turn the power off and turn it on. If problem persists, contact LS representatives.
13) “Fuse Open” trip occurs constantly.
① is the input (line) voltage normal?
☞ Check the line voltage input. If phase to phase unbalance exceeds 2%(greater than 6V for 380V input),
an AC reactor should be provided. Otherwise, inverter may get damaged and A/S fee will be charged during
Warranty period.
② is the phase sequence of the output terminal U, V, W correct?
☞ Check the level of the input signal.
③ Is the motor insulation damaged?
☞ Various types of malfunction occur when the insulation is damaged. In general, operation stops at a certain
speed (and more), overload or “OC-U (V,W)” trip occurs during regenerating. Or motor overheating and
rotating speed oscillates. This condition persists for a while and then “Fuse Open” trip occurs. It marks motor
insulation is damaged. In this case, replace the motor.
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