Cause : Maintenance signal output comes when the inverter's cumulative energization time reaches or exceeds the parameter set value. Set the time until the MT is displayed using Pr.504 Maintenance timer warning output set time (MT). "MT" does not appear when the setting of Pr.504 is the initial value ("9999").

1. The set time of maintenance timer has been exceeded.
2. Take appropriate countermeasures according to the purpose of the maintenance timer setting. Setting "0" in Pr.503 Maintenance timer clears the indication.
3. FR-E800 Instruction Manual (Function).