And Why Errors Are Not “Failures”
If you’re new to using a VFD-driven spindle, seeing an error code can feel alarming. It’s easy to assume something is broken or that you did something wrong.
In reality, most VFD errors are not failures at all. They are intentional safety features designed to protect your spindle, your electronics, and your investment.
This article explains what those errors actually mean, why they exist, and how understanding them can save you time, money, and frustration.
A VFD Is Not a Dumb Power Supply
Unlike a trim router or simple motor controller, a VFD is an active control system. It constantly monitors:
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Motor current
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Voltage levels
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Acceleration and deceleration behavior
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Internal temperatures
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Electrical faults
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Load conditions
It makes thousands of decisions per second to ensure the spindle is operating within safe limits.
When something moves outside those limits, the VFD does exactly what it was designed to do:
it stops before damage occurs.
What an Error Really Means
When a VFD throws an error, it is saying:
“I detected a condition that could damage the motor or myself, so I stopped.”
That’s it.
It does not mean:
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The spindle is ruined
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The VFD is defective
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Your setup is unusable
It means the protection system worked.
Common Examples of Protective Errors
Here are a few common scenarios where the VFD protects your equipment:
Over-Current Errors (ERR01–ERR03, ERR34)
These occur when:
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The cut is too aggressive
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The tool is too large
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The feed rate is too high
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Acceleration is too fast
The VFD sees current rising beyond safe limits and shuts down before overheating or transistor failure can occur.
Without this protection, the motor or VFD could be permanently damaged.
Over-Voltage / Under-Voltage Errors (ERR04–ERR06, ERR08)
These occur when:
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Incoming power fluctuates
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The circuit is weak or shared
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Large loads start on the same electrical line
Again, the VFD stops because operating under unstable voltage can destroy internal components.
Acceleration-Related Errors
If the spindle is commanded to accelerate too quickly, especially into a cutting load, current can spike before the motor reaches stable speed.
The VFD stops because:
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Torque demand exceeds safe limits
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The motor cannot physically respond fast enough
This protects both the motor windings and the drive electronics.
Why Repeated Resets Cause Damage
One of the most common and dangerous reactions to an error is repeatedly resetting the VFD and trying again without changing anything.
This can lead to:
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Overheating
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Driver board damage
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Current sensor failure
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Permanent VFD failure
The VFD is telling you something important. Ignoring it and forcing operation defeats the entire protection system.
The safest response to any error is to stop and understand the cause before retrying.
Why Routers “Just Keep Spinning” (And Why That’s Worse)
Trim routers don’t have protection systems like a VFD.
If overloaded, they:
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Overheat
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Lose torque
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Burn windings
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Fail silently over time
VFDs don’t allow that kind of slow, hidden damage. They stop early, loudly, and visibly so you can fix the cause instead of replacing hardware later.
Errors Are Feedback, Not Judgment
It’s important to reframe how you view VFD errors.
They are:
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Feedback from a very sensitive system
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Early warnings
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Protection events
They are not:
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Accusations
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Defects
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Signs you “did something wrong”
Every industrial CNC machine on the planet behaves this way.
The Big Takeaway
If you remember nothing else from this article, remember this:
A VFD error means your equipment was protected.
Ignoring errors is what causes real damage.
Understanding and responding correctly to VFD errors will:
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Extend spindle life
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Reduce downtime
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Prevent costly repairs
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Make your machine more reliable long-term
What to Do When an Error Appears
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Stop and note the error code
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Power down safely if needed
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Look up the specific error in our Knowledge Base
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Address the cause before restarting
Each error code article explains:
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What triggered it
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What to check first
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Whether it’s load-related, power-related, or hardware-related
Final Thought
VFDs like the Delixi EM61 are used in real industrial environments because they protect expensive equipment. Learning how and why they do that turns frustration into confidence.
Once you understand the language they speak, they become one of the most reliable parts of your CNC system.
