What is the difference between Pre-Ramp Frequency Reference (FrH) and Reference Frequency (LFr) on ATV630 and ATV930 drives?
Resolution:
The Pre-Ramp Frequency Reference (FrH) and Reference Frequency (LFr) serve different purposes in ATV630 and ATV930 drives:
Pre-Ramp Frequency Reference (FrH)
- Represents the frequency reference before ramping is applied.
- Reflects the actual commanded frequency sent to the drive, regardless of the selected reference source.
- Includes a signed value (can indicate direction).
- Read-only parameter — it cannot be modified by the user.
- Useful for monitoring the incoming speed reference signal.
Reference Frequency (LFr)
- Represents the active speed reference used by the drive.
- Can be manually adjusted (if the function is enabled).
- Typically used for remote or local speed control.
- Changes take effect immediately without pressing OK.
- Appears only when the reference adjustment function is activated.
Key Difference
- FrH = Monitoring value (input reference before ramping, read-only)
- LFr = Control value (adjustable speed reference used to operate the drive)
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Frequently Asked Questions - Schneider Electric (se.com)
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