What the hV alarm means

The servo DC bus voltage is too high — regenerative energy is not being absorbed. This is one of the faults our repair team handles on Omron SmartController (ACE / Viper / Cobra) systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Braking/regeneration circuit fault
  • Aggressive deceleration with high payload/inertia
  • Supply voltage too high
  • Aged bus capacitors
Field note: the first item on this list is what we find most often on real machines. Check it before you go deeper.

Step-by-step field fix

  1. Check the regeneration/braking resistor circuit
  2. Reduce deceleration rates on fast moves
  3. Verify the incoming supply voltage
  4. Check payload settings
  5. Power-cycle and retest; replace the regeneration hardware if the fault persists
Safety first: never bypass safety circuits or force contactors closed. If the alarm involves E-stop chains, brakes or drive power, and you are not a trained robot technician, contact a professional — wrong moves here can cost you a robot or an injury.

Still stuck? Get an engineer on the phone — right now

Tell us the alarm code, the robot model and what was happening when the alarm came up. Our engineers run these diagnostics every day, and remote diagnosis by phone or video call is free.

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Hotline: +86-20-39029800 · WhatsApp: +86-188-1886-2860

Related Drive & Power Stage alarms

D# (-1021) — Duty Cycle Exceeded (Joint N) 24 — 24V Supply Fault A# — Amplifier Fault (Joint N) h# — High Temperature — Amplifier (Joint N)
Other brands: we also keep field-fix libraries for ESTUN · INOVANCE · EFORT and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Omron hV alarm mean?

The servo DC bus voltage is too high — regenerative energy is not being absorbed. In field practice it belongs to the drive & power stage family of faults.

QCan I clear a Omron hV alarm myself?

Sometimes. Work through the step-by-step checks on this page — the first listed cause is what we find most often in the field. If the alarm returns after two attempts, or the fault involves power, brakes or safety circuits, stop and call a qualified robot service engineer.

QHow fast can a Henghuan engineer help?

On-site response in the Pearl River Delta within 30 minutes to 3 hours, across mainland China in 1-3 business days, and worldwide within 2-5 business days. Remote diagnosis by phone/WhatsApp/video is available immediately.

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 Omron documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Omron.