What the A.10 alarm means

Current through the drive power stage exceeded the protection threshold; the ESTUN servo cuts output to protect the IGBT module. This is the most common hardware-level alarm on ESTUN-driven robot axes. This is a fault we handle frequently on ESTUN ERC / ED3L controller + ESTUN servo systems — in most cases we can pin down the root cause on the first site visit.

Most common causes

  • Short circuit or ground fault in the motor power cable U/V/W
  • Motor winding insulation breakdown
  • Damaged IGBT power module in the drive
  • Acceleration too aggressive for the load
  • Water or oil ingress into a motor connector
Field note: The first item on this list is what we hit most often on real machines — clear that one before going deeper.

Step-by-step field fix

  1. Power off, wait for the DC bus to discharge, then megger the motor cable phases to ground
  2. Disconnect the motor and power up the drive alone — if A.10 returns, the power stage is dead
  3. Inspect connectors at both cable ends for coolant or oil contamination
  4. Reduce acceleration in the program and retry
  5. Replace the drive and re-run a low-speed test jog before production
Safety first: For ESTUN a-10, this alarm family involves the DC bus, which sits at several hundred volts and stays charged for minutes after power-off - touching terminals is a shock hazard. The self-serviceable action is Power off, wait for the DC bus to discharge, then megger the motor cable phases to ground; anything past that falls under the DC bus and power stage and needs a certified engineer. On ESTUN a-10: checking incoming voltage at the disconnect and looking at breakers and fuses is fine to do yourself; opening the cabinet to touch bus terminals or pulling power modules needs a qualified electrician.

How we diagnose drive alarms on site

ESTUN a-10 belongs to the drive & power stage family. On ESTUN a-10 the failing stage is matched servo drives (in-house / Inovance-class servos) on the ESTUN robot controllers (motion-control-platform based) - the fault sits on the energy chain: mains input, rectification, DC bus, braking resistor, inverter power devices and the drive board. We start reading ESTUN a-10 at the pendant alarm list (A.xxx / E.xxx segments) and the servo panel display code.

The chain involved in ESTUN a-10 runs: three-phase mains -> rectifier -> DC bus (bus capacitors) -> brake chopper / braking resistor -> inverter (IGBT) -> motor.

When ESTUN a-10 fires, the site usually reports Short circuit or ground fault in the motor power cable U/V/W first, but the real cause is often cooling: More than half of power-stage alarms are not a dead device but a device cooked by failed cooling. A stopped cabinet fan, a packed filter mat or a dusted air duct keeps IGBT junction temperature high: intermittent over-temperature first, hard fault days later. On these alarms we open the power module and look for cracked thermal paste and felted dust in the duct, then measure phase-to-phase output and insulation to frame. Swapping the module without cleaning the duct just buys the same failure again.

Field notes on this page cover ESTUN a-10 (Overcurrent); written by the Henghuan repair team, updated 2026-10-01.

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Related Drive & Power Stage alarms

A.02 — Parameter Setting Error A.30 — Regeneration Error / Regenerative Overload A.40 — Main Circuit Overvoltage A.41 — Main Circuit Undervoltage A.71 — Overload — Instantaneous High Load A.72 — Overload — Continuous Over-torque
Same family: this code belongs to the Drive & power stage alarms family - the page collects all Drive & power stage-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for INOVANCE · EFORT · JAKA and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the ESTUN a-10 alarm mean?

Current through the drive power stage exceeded the protection threshold; the ESTUN servo cuts output to protect the IGBT module. This is the most common hardware-level alarm on ESTUN-driven robot axes. This is a fault we handle frequently on ESTUN ERC / ED3L controller + ESTUN servo systems — in most cases we can pin down the root cause on the first site visit. ESTUN a-10 sits in the drive & power stage family; on our work orders the highest-frequency trigger for this code is "Short circuit or ground fault in the motor power cable U/V/W".

QCan I clear a ESTUN a-10 alarm myself?

Whether ESTUN a-10 clears on its own depends on the outcome of "Power off, wait for the DC bus to discharge, then megger the motor cable phases to ground". Finish the flow with "Replace the drive and re-run a low-speed test jog before production" to confirm ESTUN a-10 - do not skip it. If that step is clean, the second most frequent cause on ESTUN a-10 is "Motor winding insulation breakdown". Do not chase takt through a repeating ESTUN a-10. Left alone, drive & power stage faults tend to graduate from repairable to must-replace.

QFor drive/power alarms like ESTUN a-10, what spares do you bring on site?

The commonest causes we see on ESTUN a-10 are "Short circuit or ground fault in the motor power cable U/V/W, Motor winding insulation breakdown, Damaged IGBT power module in the drive", so we stock the van against those. For ESTUN a-10 specifically, we stock the van along the energy chain: braking resistors, bus capacitors, input fuses, drive-board supply parts and the common power modules for the brand. For ESTUN a-10, drive alarms usually stop the whole line, so they sit at the front of our dispatch queue. Before we roll, tell us what ESTUN a-10 shows on the pendant alarm list (A.xxx / E.xxx segments) and the servo panel display code and what the machine was doing - phone or video triage is free.

The notes on ESTUN a-10 were summarized by the Henghuan Robotics repair team from on-site service. The alarm interpretation is our empirical summary for troubleshooting reference and may vary by controller and software version — please check ESTUN documentation or contact us with questions. Henghuan is an independent service provider, not affiliated with or endorsed by ESTUN.