What the 34400 alarm means

The drive DC link voltage exceeded its limit — regenerative energy is not being dissipated, typically during hard deceleration. This is one of the most common faults in our repair logs for the ABB IRC5 / OmniCore (RobotWare) platform, and the first inspection typically locates the cause.

Most common causes

  • Faulty or disconnected braking resistor / bleeder circuit
  • Deceleration ramps too aggressive for the payload
  • Drive hardware fault in the braking chopper
  • Supply voltage consistently high
Field note: Field experience says the first cause is the most likely — verify it before moving on to the rest.

Step-by-step field fix

  1. Check the braking resistor and its connections
  2. Review program deceleration and payload data
  3. Verify facility supply voltage
  4. Replace the drive unit if the chopper stage is faulty
Safety first: For ABB 34400, 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. On site you may not carry out the first step yourself: Check the braking resistor and its connections. Beyond that it is the DC bus and power stage work - leave it to a professional. On ABB 34400: 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

ABB 34400 belongs to the drive & power stage family. On ABB 34400 the failing stage is DSQC drive modules (DSQC 600 generation; OmniCore drive units) on the IRC5 / OmniCore - the fault sits on the energy chain: mains input, rectification, DC bus, braking resistor, inverter power devices and the drive board. We start reading ABB 34400 at the FlexPendant event log and system diagnostics, with the cabinet status LEDs.

The chain involved in ABB 34400 runs: three-phase mains -> rectifier -> DC bus (bus capacitors) -> brake chopper / braking resistor -> inverter (IGBT) -> motor.

Faulty or disconnected braking resistor / bleeder circuit is common on ABB 34400, but look at the duty cycle: Cells with high-inertia loads or frequent start-stop cycles return far more regenerative energy than a plain transfer cell, and the braking resistor lives in a hot cycle that shortens its life. When we suspect this family we ask what changed: if the takt was raised recently or a heavier fixture went on, the alarm cluster usually lines up with that process change. Replacing the resistor alone will not fix it - the chopper rating and resistor wattage have to be re-checked against the new duty.

Field notes on this page cover ABB 34400 (DC Link Voltage Too High); written by the Henghuan repair team, updated 2026-10-01.

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Related Drive & Power Stage alarms

34316 — Motor Current Error 34200 — Communication with All Drive Units Interrupted 34251 — Missing Phase of Input Power
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 Yaskawa · Universal Robots · Kawasaki and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the ABB 34400 alarm mean?

The drive DC link voltage exceeded its limit — regenerative energy is not being dissipated, typically during hard deceleration. This is one of the most common faults in our repair logs for the ABB IRC5 / OmniCore (RobotWare) platform, and the first inspection typically locates the cause. ABB 34400 sits in the drive & power stage family; on our work orders the highest-frequency trigger for this code is "Faulty or disconnected braking resistor / bleeder circuit".

QCan I clear a ABB 34400 alarm myself?

Whether ABB 34400 clears on its own depends on the outcome of "Check the braking resistor and its connections". Finish the flow with "Replace the drive unit if the chopper stage is faulty" to confirm ABB 34400 - do not skip it. If that step is clean, the second most frequent cause on ABB 34400 is "Deceleration ramps too aggressive for the payload". Two attempts and still there means stop: ABB 34400 involves the DC bus and power stage, and running ABB 34400 on can turn a repairable fault into a replacement.

QFor drive/power alarms like ABB 34400, what spares do you bring on site?

The commonest causes we see on ABB 34400 are "Faulty or disconnected braking resistor / bleeder circuit, Deceleration ramps too aggressive for the payload, Drive hardware fault in the braking chopper", so we stock the van against those. For ABB 34400 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 ABB 34400, drive alarms usually stop the whole line, so they sit at the front of our dispatch queue. Before we roll, tell us what ABB 34400 shows on the FlexPendant event log and system diagnostics, with the cabinet status LEDs and what the machine was doing - phone or video triage is free.

This page on ABB 34400 was compiled from actual repair records of the Henghuan Robotics repair team. Alarm notes are our own summary for troubleshooting reference only and may vary with controller and software version — please consult ABB documentation or contact us if in doubt. Henghuan is an independent service provider, not affiliated with or endorsed by ABB.