# ACOPOS UDC\_ACT breakdown after about 2min with constant torque and velocity **URL:** \ **Category:** Mechatronics & Motion\ **Tags:** acopos-p3\ **Created:** [April 25, 2025, 6:50am UTC](https://community.br-automation.com/t/acopos-udc-act-breakdown-after-about-2min-with-constant-torque-and-velocity/6737 "2025-04-25T06:50:00Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![BES-RSB](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/bes-rsb/32/409_2.png) [@BES-RSB](https://community.br-automation.com/u/BES-RSB)\ **Post date:** [April 25, 2025, 6:50am UTC](https://community.br-automation.com/t/acopos-udc-act-breakdown-after-about-2min-with-constant-torque-and-velocity/6737/1 "2025-04-25T06:50:00Z")
Hi there, We are confronted with a phenomenon where after a while (about 2min) on constant speed and torque the ACOPOS-P3 UDC\_ACT (= the DC-BUS Voltage) breaks down. ![image](https://europe1.discourse-cdn.com/brcommunity/original/2X/2/27ed6b003f1bd0bb833f1a94651f4733388223df.png) If we run the motor with 1000rpm all parameters remain OK. If we run the motor with about 1200rpm the UDC breaks down after a while. The main power-supply 3x400V 64A is also OK and stable what we know now. Question: Does anyone have a idea what might be the root cause of this breaking down UDC? We stuck right now… Thanks a lot! ---
**Author:** ![Peter\_Brix](https://avatars.discourse-cdn.com/v4/letter/p/FF8800/32.png) [@Peter\_Brix](https://community.br-automation.com/u/Peter_Brix)\ **Post date:** [April 25, 2025, 10:22am UTC](https://community.br-automation.com/t/acopos-udc-act-breakdown-after-about-2min-with-constant-torque-and-velocity/6737/2 "2025-04-25T10:22:35Z")
I would expect that the supply on the Acopos terminals goes directly to the rectifiers to create the DC Bus Voltage. So either you’re drawing more current than can be rectified and smoothed (unlikely) or the supply to the Acopos is throttled or isn’t stable. Check the supply cabling for correct size and tight connection. I’d suggest clamping an Amperemeter to each one of the phases in turn (one by one). ---
**Author:** ![system](https://europe1.discourse-cdn.com/brcommunity/original/1X/a202d64f0f03e22a662ed33fbbca6879f1efb794.jpeg) [@system](https://community.br-automation.com/u/system)\ **Post date:** [July 10, 2025, 8:53pm UTC](https://community.br-automation.com/t/acopos-udc-act-breakdown-after-about-2min-with-constant-torque-and-velocity/6737/3 "2025-07-10T20:53:31Z")
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**Author:** ![michael.bertsch](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/michael.bertsch/32/239_2.png) [@michael.bertsch](https://community.br-automation.com/u/michael.bertsch)\ **Post date:** [July 11, 2025, 8:10am UTC](https://community.br-automation.com/t/acopos-udc-act-breakdown-after-about-2min-with-constant-torque-and-velocity/6737/4 "2025-07-11T08:10:12Z")
Any Updates on this Thread, was the issue solved, can you give us Feedback? ---
**Author:** ![kovarj](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/kovarj/32/537_2.png) [@kovarj](https://community.br-automation.com/u/kovarj)\ **Post date:** [September 18, 2025, 1:32pm UTC](https://community.br-automation.com/t/acopos-udc-act-breakdown-after-about-2min-with-constant-torque-and-velocity/6737/5 "2025-09-18T13:32:58Z")
closed due to inactivity of author. ---
**Author:** ![BES-RSB](https://dub1.discourse-cdn.com/brcommunity/user_avatar/community.br-automation.com/bes-rsb/32/409_2.png) [@BES-RSB](https://community.br-automation.com/u/BES-RSB)\ **Post date:** [September 19, 2025, 6:03am UTC](https://community.br-automation.com/t/acopos-udc-act-breakdown-after-about-2min-with-constant-torque-and-velocity/6737/6 "2025-09-19T06:03:42Z")
Why there is no new status: the phenomenon was highly reproducible at the customer’s site. But then: suddenly gone. No further reports since then. Meaning: no conclusion possible. Unfortunately. Closed: fits. Thanks, Jaroslav.