What is a servo press?

A servo press uses servo motors for precise force and position control during forming operations.

How do I calculate servo press tonnage?

Use our free tonnage calculator at servopress.club/tonnage-calculator.html

ABB ACS880 Fault 7010: DC Bus Overvoltage on Servo Press

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.

anna_controls

Fault 7010 on ACS880 during the return stroke is classic regenerative overvoltage. The motor acts as a generator during deceleration and pumps energy back into the DC bus. If the braking resistor cannot absorb it fast enough, the bus voltage spikes. Check the braking resistor with an ohmmeter. If it reads open circuit, it has burned out and all regen energy goes straight to the bus capacitors.

dave_toolmaker

7010 during the return stroke means the regenerated energy is exceeding the DC bus voltage limit. Three fixes in order of preference: 1) Add or upgrade the braking resistor to absorb more energy. 2) Slow down the return stroke speed. 3) Add DC bus capacitors to buffer the energy. Option 1 is usually the cheapest and most effective.