| Motor Identification Error | When conduction the parameter identification, the fault occurs in motor |
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ERR18 – Motor Identification Error
What this means
ERR18 indicates that the VFD encountered an error while performing motor parameter identification.
Motor identification is a process where the VFD attempts to electrically characterize the motor so it can optimize control, torque delivery, and protection behavior.
If this process fails, the VFD will report ERR18.
Why This Happens
During motor identification, the VFD expects the motor to:
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Be correctly wired
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Match the configured motor parameters
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Be electrically stable and unloaded
If the VFD cannot reliably measure motor characteristics, it aborts the process.
Most Common Causes We See
1. Motor parameters do not match the motor (most common)
The VFD relies on correct motor data such as:
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Rated voltage
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Rated current
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Rated frequency
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Rated power
If these do not match the motor’s nameplate, identification may fail.
2. Motor or cable not connected properly
Examples:
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Loose motor connector
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Incorrect phase wiring
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Poor electrical contact
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Damaged or partially broken motor cable
The VFD must see all three phases cleanly during identification.
3. Motor not in a suitable state for identification
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Tool installed and contacting material
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Spindle mechanically loaded
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Spindle unable to rotate freely
Motor identification should always be done with no cutting load.
4. Identification attempted in an unsupported mode
Some VFDs:
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Do not require motor identification
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Are pre-configured and do not benefit from re-identification
Running identification unnecessarily can introduce issues.
What to Check First
Step 1: Verify motor parameters
Confirm all motor-related parameters match the spindle’s nameplate:
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Voltage
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Current
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Frequency
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Power rating
Do not guess or approximate these values.
Step 2: Inspect motor wiring
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Power down and unplug the VFD
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Verify motor connector is fully seated
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Check for loose terminals or damaged insulation
Step 3: Ensure the spindle is unloaded
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Remove any tool from the spindle
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Make sure the spindle can rotate freely
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Do not perform identification while mounted in material
Step 4: Determine whether identification is required
Many spindle systems:
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Are already configured correctly
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Do not require motor identification to operate safely
If the spindle runs normally without identification, repeating the process may be unnecessary.
What ERR18 Is Not
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Not a cutting load issue
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Not a feed rate or RPM problem
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Not EMI related
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Not a controller or software fault
ERR18 only relates to motor identification, not normal operation.
When to Contact Support
If:
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Motor parameters are confirmed correct
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Wiring is verified
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Identification still fails
Then technical support can help determine whether:
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Identification is required for your setup
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Default parameters should be used instead
Photos of the motor nameplate and parameter screens are helpful.
Summary
ERR18 means the VFD was unable to complete motor identification.
Most common causes:
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Incorrect motor parameters
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Wiring issues
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Mechanical load during identification
In many cases, motor identification is optional and not required for normal spindle operation.
