Err06 - PwnCNC

Err06

Over-voltage at deceleration

When the frequency inverter runs at constant speed, DC voltage of the main circuit exceeds this set value. The detected over-voltage value is the same as above

Check whether the input voltage is too high;
Check whether the bus voltage display is normal;
Delay the deceleration time;
Check whether the motor is dragged to run by external force in the process of deceleration;
Install additional brake unit and brake resistance;

ERR06 – Over-Voltage During Deceleration

What this means

ERR06 occurs when the VFD detects that the DC bus voltage rises above a safe limit while the spindle is slowing down.

When a spindle decelerates, it naturally generates energy. If that energy cannot be absorbed or dissipated quickly enough, voltage builds up on the DC bus. ERR06 is triggered to protect the VFD from damage.

This error happens while the spindle is stopping, not during cutting or steady operation.

Detected Over-Voltage Thresholds

The over-voltage limits are the same as other over-voltage errors:

Level S1 (110 V systems): ~240 V
Level S2 / T2 (220 V systems): ~400 V
Level T4 (380–480 V systems): ~800 V

Most Common Causes (Real-World)

1. Deceleration time is too aggressive

This is the most common cause of ERR06.

If the spindle is commanded to stop too quickly, the regenerative energy produced during braking overwhelms the VFD’s ability to absorb it, causing the DC bus voltage to spike.

This is especially common with:

Higher spindle RPMs
Larger or heavier spindles
Frequent stop/start cycles

2. Abrupt stop commands

Examples:

Emergency stops
Feed hold or program stop at high RPM
Tool changes that command rapid spindle stops

These force aggressive deceleration and can trigger ERR06.

3. External forces driving the spindle

If the spindle is still being mechanically driven while decelerating, voltage can rise rapidly.

Examples:

Tool still engaged in material during stop
Axis motion continuing briefly while spindle slows
Cutting forces “pushing” the spindle

4. High input voltage

If incoming line voltage is already high, the margin before hitting the over-voltage threshold is smaller, making ERR06 more likely during deceleration events.

What to Do First (Recommended Order)

Step 1: Increase deceleration time

This resolves most ERR06 cases.

Increase the VFD deceleration time
Avoid commanding the spindle to stop abruptly

⚠️ For Masso users:
Ensure the spindle deceleration time in Masso matches the VFD deceleration setting.

Step 2: Adjust workflow to avoid abrupt stops

Let the spindle coast down naturally when possible
Avoid stopping the spindle while fully engaged in material
Reduce reliance on emergency stops unless necessary

Step 3: Review cutting strategy

Ensure toolpaths don’t force the spindle while stopping
Avoid conditions where axis motion continues aggressively as the spindle slows

Step 4: Verify electrical conditions

Measure incoming voltage if possible
Confirm proper grounding and solid power connections

Step 5: Consider a braking resistor (advanced)

If ERR06 persists in high-speed or high-inertia applications:

A braking resistor gives the VFD a safe path to dissipate excess energy
Usually only required in more aggressive or production environments

Most hobby setups do not need a brake resistor.

Important Notes

ERR06 is a protective fault, not a hardware failure
It does not indicate a damaged spindle or VFD
Repeated ERR06 events mean the spindle is being stopped too aggressively

Summary

ERR06 means the VFD is seeing excessive DC bus voltage while the spindle is slowing down.

In most cases:

Increase deceleration time
Avoid abrupt stop commands
Ensure controller and VFD deceleration settings match

If ERR06 continues after increasing deceleration time, contact support with details about your spindle RPM, deceleration settings, and how the spindle is being stopped.