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ErrorLib — Industrial Fault Code Library

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Maintenance signal output

Maintenance Signal Output

Mitsubishi Electric · FR-D700 Inverter

What does Maintenance signal output mean?

The cumulative energization time has exceeded the value set in the maintenance output timer (Pr. 503 Maintenance timer). This is a warning indicating that routine scheduled maintenance is due based on operating hours. While not a fault that stops operation, ignoring it can lead to component degradation and potential future failures.

Common Causes

  • The cumulative run time (or energization time) of the inverter has exceeded the threshold set in Pr. 503 (Maintenance timer).
  • The maintenance timer was set to a low value (e.g., for initial break-in period) and has now been reached.
  • Routine maintenance has been overlooked or postponed, leading to the timer expiring.
  • The inverter has been powered ON for a long duration without the timer being reset after maintenance.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Record the current cumulative run time (e.g., using Pr. 502 Cumulative operation time) to track usage.

  2. 2

    Perform scheduled maintenance activities on the inverter and motor, such as cleaning cooling fins, checking terminal connections, and inspecting fan operation.

  3. 3

    After completing maintenance, reset the maintenance timer by writing '0' to Pr. 503 (Maintenance timer) to clear the warning.

  4. 4

    Adjust Pr. 503 (Maintenance timer) to a new interval (e.g., 8760 hours for annual maintenance) according to the preventive maintenance schedule.

  5. 5

    Log the maintenance date and time in the equipment's service history.

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Verified technical data. Last updated: April 2026

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Source: Mitsubishi Electric FR-D700 Inverter
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