admin Fault 7010 (DC bus overvoltage) on ABB ACS880 drives is common on servo press applications because regenerative braking during the press return stroke feeds energy back into the DC bus. ## Why Servo Presses Generate Regenerative Energy During the return stroke (BDC to TDC), the servo motor decelerates the slide and flywheel. This deceleration generates electrical energy that flows back into the DC bus. If the bus cannot absorb this energy, voltage rises until fault 7010 triggers. Typical DC bus voltage: 540-680V DC (for 400V AC input) Fault threshold: typically 810V DC (ACS880 default) ## Root Causes **Braking resistor issues (most common):** - Braking resistor undersized for press duty cycle - Braking resistor connection open (check R+ and R- terminals) - IGBT chopper fault preventing resistor activation **Drive configuration:** - Parameter 95.01 (Supply voltage) set incorrectly - Overvoltage controller disabled (parameter 30.30) - Deceleration ramp too fast for load inertia **Supply issues:** - Supply voltage too high (check incoming voltage) - Power factor correction capacitors on same supply causing voltage spikes ## Diagnostic Steps 1. Check parameter 01.11 (DC bus voltage) during fault ??record peak value 2. Verify braking resistor is connected: measure resistance between R+ and R- (should match nameplate) 3. Check parameter 43.06 (braking resistor power) ??must be set to actual resistor rating 4. Monitor parameter 01.11 during slow test stroke ??watch for voltage rise during return ## Sizing the Braking Resistor For a servo press, calculate peak regenerative power: ``` P_regen = 0.5 ? J ? (?_max? - ?_min?) ? SPM/60 ``` Where J = total inertia (kg?m?), ? = angular velocity (rad/s) Braking resistor should be rated for at least 150% of calculated peak regenerative power.
admin Related: see also the discussion on [ABB ACS880 fault 7121 motor stall](https://servopress.club/d/132-132-abb-acs880-fault-7121-motor-stall-on-servo-press-causes-and-parameter-fix) for complementary technical detail.