Normal fan supply voltage

The check usually follows an external fan alarm (ExtFanErr), which the inverter raises when it detects that a cooling fan has failed. Listed causes of that alarm include a blocked fan, a fan past the end of its service life, and poor contact at the fan socket connector. Suggested first steps are to watch for about 5 minutes to see if the alarm clears by itself, check the fan blades for foreign objects, and then switch off the 3-phase supply and reboot. A failed fan is one of the known reasons an inverter overheats and reduces its output because of temperature. To reach the fan, its connector and the power supply connector are unplugged inside the inverter tray.

<!-- review notes

• sentence 1: support check: partial - ExtFanErr is defined as cooling fan failure, but passages don't say a check usually follows it or that the inverter 'detects' it (the definition says 'by visual check').
• sentence 3: support check: partial - Observe 5 minutes, check foreign objects on fan blades, and switch off 3-phase supply and reboot appear, but the ordering is muddled and the fan blade check appears attached to a fragment of text, so the sequence is only loosely supported.
• sentence 5: support check: partial - Passages say to disconnect the internal fan and power supply connectors at the PCBA tray, but not that this is done to reach the fan; it is part of tray removal. -->