Fagor alarm 4027: The drive has started up again
CNC 8055 SERCOS drive error (DDS) · Fagor DDS drives
What it means
A drive dropped and regained its auxiliary/control power during operation - SERCOS re-init trips the whole ring.
Likely causes
- loose 24 V auxiliary supply wiring or failing APS-24 module
- mains dips/contactors chattering feeding the PS module
- drive internal power-supply stage intermittent (repeat offender = drive)
Triage note: Identify the culprit drive from the SERCOS LOG / its 7-segment display restart, then monitor its 24 V input with a chart recorder - dips point upstream, none point to the drive.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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APS-24
Auxiliary 24 V DC supply module · Common cause
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PS-25B4 / XPS-25
Power supply module (control-power section) · Common cause
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AXD/SPD affected size module
Drive module if only one unit keeps resetting · Check if others ruled out
Need the part urgently?
Send us alarm 4027 with your machine details — typical RFQ turnaround is 24–48h.