Control Techniques / Nidec fault record

PS.24V: 24 V Control Supply Overload / Fault

Unidrive reports PS.24V, loses option/module supply, or drops control logic when external loads are connected.

Deep supply/option route10 min read

Scope of this technical record

Routes Unidrive PS.24V through external 24 V loads, option modules, encoder/sensor supply, terminal wiring and internal supply evidence.

Safety boundary

Do not overfuse, bypass or short external 24 V protection. Secure the machine before disconnecting control wiring or option-module loads.

Unidrive PS.24V route

124V rail
2External loads
3Option modules
4Feedback supply
5Internal supply

PS.24V is a branch-isolation problem before it is an internal supply claim.

PS.24V load-isolation image

Unidrive PS 24V external load option module and internal supply route diagram
The image turns PS.24V into a branch-isolation record: external loads first, option modules second, internal supply only after evidence.

Service decision coverage

PS.24V pages should behave like an intake checklist for control wiring. The technician must prove external loads and option modules before an internal supply claim.

Observed situationDecision neededEvidence that satisfies the case
Trip at power-upHard short or internal supplyExternal branch isolation result
Trip when device actuatesSensor/actuator/cable branchBranch current and cable inspection
Trip after module fittedOption-module loadModule identity and removed-module test

PS.24V is a load-isolation route

PS.24V should be treated as a branch-isolation problem first. External sensors, option modules, feedback devices, terminal wiring and added controls can overload or short the 24 V rail before the internal supply is actually failed.

Load-isolation matrix

The best evidence shows which branch makes the fault appear.

PS.24V evidence

BranchEvidenceRepair direction
External I/O loadsFault clears when branch isolatedField wiring or sensor issue
Feedback deviceEncoder supply/current issueFeedback path
Option moduleFault follows moduleModule or configuration
Terminal wiringShort or incorrect external connectionPanel wiring
Internal supplyFault persists with external loads provenControl-board/supply evaluation

Repair boundary

Only after external loads and option modules are isolated should the internal 24 V supply be considered suspect. The support request should state which branches were removed and what changed.

Field record checklist

  • External loads
  • Option modules
  • Feedback supply
  • Branch isolation result
  • Internal rail evidence

Technical basis and reference documents

This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.

Unidrive SP trip-code referenceDrives and Automation

Public trip-code context for internal power-supply trips.

Diagnostic workflow

Evidence intake

Turn this record into a qualified service request

A repair decision is much more reliable when the request includes the exact identity of the drive, the first fault evidence and the machine condition when the symptom appeared.

  • Complete drive type code / MLFB or nameplate model
  • Fault code, fault value and first event before reset
  • When the event appears: power-up, enable, ramp, run, decel or stop
  • Motor/cable connected or isolated during the symptom
  • Visible board, option-card, module and connector identifiers
  • Previous repair history, replacement parts and repeat-failure pattern
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