What the 26107 alarm means

The intermediate-circuit voltage of the KSP exceeded its limit, typically during deceleration when regenerative energy cannot be dissipated. This is a high-frequency ticket for our KUKA repair team, and on KRC2 / KRC4 / KRC5 (KSS) systems one inspection usually identifies the fault.

Most common causes

  • Faulty or disconnected braking (ballast) resistor
  • Defective braking chopper inside the KSP
  • Deceleration ramps too aggressive for the load
  • Aged DC link capacitors
Field note: The top-listed cause has the highest hit rate, so checking it first narrows things down fast.

Step-by-step field fix

  1. Check the ballast resistor and its wiring (see also 12005 and 26122)
  2. Verify the braking chopper function in the KSP
  3. Soften deceleration ramps or reduce payload in the program
  4. Replace the KSP if overvoltage recurs with a healthy resistor
Safety first: For KUKA 26107, 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. What you can check yourself first is Check the ballast resistor and its wiring (see also 12005 and 26122); the DC bus and power stage handling is not a DIY job. On KUKA 26107: 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

KUKA 26107 belongs to the drive & power stage family. On KUKA 26107 the failing stage is KPP power packs and KSP servo packs (next-generation drive modules on KRC5) on the KRC2 / KRC4 / KRC5 - the fault sits on the energy chain: mains input, rectification, DC bus, braking resistor, inverter power devices and the drive board. We start reading KUKA 26107 at the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs.

The chain involved in KUKA 26107 runs: three-phase mains -> rectifier -> DC bus (bus capacitors) -> brake chopper / braking resistor -> inverter (IGBT) -> motor.

Bottom line up front: Faulty or disconnected braking (ballast) resistor is the first suspect for KUKA 26107, but read it along the energy chain: Any link on this chain dropping voltage shows up at the end as a drive alarm, so order matters. We measure the mains first: more than 3% phase imbalance is enough to sag the bus under load, and plenty of bus over/under-voltage alarms are actually a grid problem wearing a robot costume. Mains fine, then the bus capacitors - bulged cases, weeping electrolyte or a lifted vent mean replacement; capacitance down 20% or more cannot hold the bus during braking. Last, the braking resistor: healthy values sit in the tens of ohms depending on rating, and an open or drifted resistor trips regenerative overvoltage directly.

Field notes on this page cover KUKA 26107 (KSP DC Link Overvoltage (Axis N)); written by the Henghuan repair team, updated 2026-10-01.

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Related Drive & Power Stage alarms

12005 — Ballast Resistor Temperature Sensor — Wire Disconnection 26012 — General Servo Error (Drive N) 26013 — General Inverter Failure (Drive N) 26108 — KSP DC Link Undervoltage (Axis N) 26111 — KSP Device Overtemperature (Axis N) 26122 — KSP Braking Resistor Fault (Axis N)
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 ABB · Yaskawa · Universal Robots and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the KUKA 26107 alarm mean?

The intermediate-circuit voltage of the KSP exceeded its limit, typically during deceleration when regenerative energy cannot be dissipated. This is a high-frequency ticket for our KUKA repair team, and on KRC2 / KRC4 / KRC5 (KSS) systems one inspection usually identifies the fault. KUKA 26107 sits in the drive & power stage family; on our work orders the highest-frequency trigger for this code is "Faulty or disconnected braking (ballast) resistor".

QCan I clear a KUKA 26107 alarm myself?

Whether KUKA 26107 clears on its own depends on the outcome of "Check the ballast resistor and its wiring (see also 12005 and 26122)". Finish the flow with "Replace the KSP if overvoltage recurs with a healthy resistor" to confirm KUKA 26107 - do not skip it. If that step is clean, the second most frequent cause on KUKA 26107 is "Defective braking chopper inside the KSP". If KUKA 26107 returns after two clears, or the checks point at Faulty or disconnected braking (ballast) resistor, stop the cell and call a professional robot repair engineer.

QFor drive/power alarms like KUKA 26107, what spares do you bring on site?

The commonest causes we see on KUKA 26107 are "Faulty or disconnected braking (ballast) resistor, Defective braking chopper inside the KSP, Deceleration ramps too aggressive for the load", so we stock the van against those. For KUKA 26107 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 KUKA 26107, drive alarms usually stop the whole line, so they sit at the front of our dispatch queue. Before we roll, tell us what KUKA 26107 shows on the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs and what the machine was doing - phone or video triage is free.

This page on KUKA 26107 was written by the Henghuan Robotics repair team from field service experience. Alarm descriptions are our own summary for troubleshooting reference and may vary by controller and software version — when in doubt, check your KUKA documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by KUKA.