Bolt X / Yaskawa YRC1000 — Generator Too Small Causes Permanent Damage¶
Summary¶
The Bolt X uses a Yaskawa YRC1000 controller with a regenerative braking circuit. During hard decelerations — particularly on track — the robot generates power back into the supply. If a generator cannot absorb this regenerated energy, it will damage components inside the YRC1000. This damage is permanent and not covered by Yaskawa or MRMC warranty. A real incident occurred on a 22kVA generator being used alone (without other loads). Minimum recommended generator: 50kW, with other high-power equipment (lights, etc.) running from the same supply.
DANGEROUS — Can permanently destroy the YRC1000 controller
Running a Bolt X on track from a small or solo generator risks catastrophic, non-warranty-covered damage to the Yaskawa YRC1000 controller. Read this page carefully before any location shoot.
Symptoms / Incident¶
- Robot arm fails during a fast deceleration on track
- YRC1000 controller shows faults after aggressive track deceleration
- System was working from the generator previously but fails under hard stops
Systems Affected¶
- Bolt X on Track (Yaskawa YRC1000 controller)
- Bolt X on Pedestal may have lower risk but the same regenerative circuit applies
Why This Happens¶
The Yaskawa YRC1000 contains a regenerative braking circuit. When the Bolt X decelerates rapidly (especially at the end of a fast track run), the arm motors act as generators and feed power back toward the supply. In a mains/grid power environment or with a large generator that has other loads connected, this energy is simply absorbed by the grid or consumed by other equipment.
With a small or solo generator:
- The generator cannot absorb the regenerated power
- Voltage spikes back into the YRC1000
- Internal components are damaged
- Yaskawa does not cover this under warranty — they discourage generator use specifically because of this
"If the generator is not capable to absorb the excess energy produced by robot hard decelerations, especially on track, some component in the controller may be damaged and would need to be replaced. This kind of damage is not covered by either Yaskawa or MRMC warranty." — Gordon (MRMC), 2022-07-04
The Incident¶
In July 2022, a Bolt X on track was being used on a location shoot in Europe. The generator was 22kVA, and it was powering only the Bolt X — no other significant loads were running from it. The rig had previously worked from that generator on other occasions without incident. During one hard deceleration on track, the rig failed mid-pass. Yaskawa's assessment was that regenerated power from the deceleration could not be absorbed by the generator.
"The generator being used was 22KVA... the rig failed during deceleration when the robot is generating power. Yaskawa's assumption based on the data provided so far is that the problem is the regeneration of power of the deceleration." — Gordon (MRMC), 2022-07-06
Solution / Requirements for Location Use¶
Minimum generator size¶
50kW minimum for Bolt X on track at location.
This is a minimum — larger is better. Most US on-set generators are 100–150kW, which is why incidents have been rare in US productions.
Other equipment must share the generator¶
Running the Bolt X alone on a generator is high risk. Connect lights and other high-power equipment to the same generator so that any regenerated power is absorbed by those loads.
"In scenarios where a larger generator is used together with lights and other equipment running from the same generator, this actually would help to dissipate any excess regenerated power as it simply will be used up by the other load and the generator has to just produce less rather than absorb it." — Gordon (MRMC), 2022-07-06
Avoid hard decelerations on small generators¶
If you must use a smaller generator, reduce deceleration rates significantly to minimise regenerated power spikes. This is a last resort, not a solution.
Mains power is preferred¶
Where possible, use mains/grid power for the Bolt X on track. Grid power can absorb regenerated energy without issues.
Warranty Note¶
Not covered by warranty
Damage caused by regenerative power from an undersized or solo generator is not covered by Yaskawa or MRMC warranty. Yaskawa explicitly discourages use of engine-driven generators for this reason. Repair costs for YRC1000 internal component damage are significant.
Source: talk.mrmoco.com — Bolt X on Track – location power requirements – Warning — Posts by Gordon (MRMC), 2022-07-04 to 2022-07-07
Official Documentation¶
Related Issues¶
- See also: Medium Turntable 48V PSU Trips on Hard Deceleration — similar regenerative deceleration issue with smaller motor equipment
Revision History¶
| Date | Change | Editor |
|---|---|---|
| 2026-05-29 | Initial extraction from forum topic 996 | Tom D / Claude Code |