The fixes engineers usually try are changing the minimum-frequency limit, reducing acceleration time, or accepting a short active portion of the potentiometer travel. None corrects the command slope. The number that matters is the relationship between analog input voltage and commanded frequency: map 0 V to 40 Hz and 10 V to 50 Hz.
Wrong fixes and their effects
Setting F01.13 to 40 Hz limits the resulting frequency, but it does not rescale the analog input. The drive reaches the limit before the potentiometer reaches its endpoint, so the remaining rotation produces no frequency change. This dead travel is input-command saturation, not a potentiometer-resolution problem.
| Attempt | Observed effect | Why it fails |
|---|---|---|
Set F01.13 to 40 Hz
|
The command stops decreasing at 40 Hz
|
The drive clamps the frequency after applying the original analog scaling. |
| Change acceleration or deceleration behavior | The motor may reach a command faster or slower | Ramp timing does not change which voltage represents 40 Hz or 50 Hz. |
| Use only the active part of the potentiometer | The required frequency range remains available | A small angular movement still represents the entire 40-50 Hz adjustment, reducing usable resolution. |
| Replace the potentiometer without testing its output | The same dead region may remain | A correctly operating potentiometer cannot correct a drive-side scaling error. |
Voltage-to-frequency relationship
A potentiometer produces a continuously variable voltage, while the analog-input scaling converts that voltage into a frequency reference. With a maximum frequency of 50 Hz, the requested lower endpoint of 40 Hz is 80% of maximum:
40 Hz / 50 Hz × 100% = 80%
The upper endpoint is:
50 Hz / 50 Hz × 100% = 100%
Therefore, assign the input endpoints as 0 V = 80% and 10 V = 100%. Between those points, the intended linear command is:
f = 40 Hz + (10 Hz × Vin / 10 V)
This gives a slope of 1 Hz/V. At the two endpoints, 0 V commands 40 Hz and 10 V commands 50 Hz. At the midpoint, 5 V should command approximately 45 Hz. The full electrical span and the full mechanical rotation now cover only the required 10 Hz band.
No current rating, analog-input impedance, potentiometer resistance, filter time, or input-conversion resolution is specified here. Read those quantities from the drive documentation and potentiometer datasheet before selecting or replacing hardware. This setup changes reference scaling; it does not establish the permissible current through the potentiometer.
Parameter map
| Parameter | Value | Role in this configuration | Quantity to check |
|---|---|---|---|
F01.12 |
50 |
Sets the upper frequency basis used for the requested range | Drive display or parameter screen |
F01.13 |
0 |
Removes the separate 40 Hz clamp that created dead potentiometer travel |
Drive parameter screen |
F05.50 |
0% |
Defines the low analog-signal point, corresponding to 0 V
|
Analog-input setup screen |
F05.51 |
80% |
Assigns 40 Hz to the low signal point |
Calculated from 40/50
|
F05.52 |
100% |
Defines the high analog-signal point, corresponding to 10 V
|
Analog-input setup screen |
F05.53 |
100% |
Assigns 50 Hz to the high signal point |
Calculated from 50/50
|
The paired values describe two coordinates on the analog transfer function: low input/low output and high input/high output. Treat each pair as a point rather than interpreting every percentage as a frequency by itself.
Configuration procedure
- Record the existing values of
F01.12,F01.13, andF05.50throughF05.53so the previous configuration can be restored. - Confirm that the connected analog input is the active frequency-command source. If the drive follows another source, changing analog scaling will have no effect on the running reference.
- Set
F01.12 = 50andF01.13 = 0. - Set the low input coordinate to
F05.50 = 0%and its output coordinate toF05.51 = 80%. - Set the high input coordinate to
F05.52 = 100%and its output coordinate toF05.53 = 100%. - Save the parameters using the drive's normal parameter-entry process.
- Rotate the potentiometer slowly from minimum to maximum while observing the frequency reference. The displayed command should increase continuously from
40 Hzto50 Hz.
Make parameter changes under the operating conditions required by the drive documentation. A displayed reference and actual motor speed are different quantities: slip, load, control mode, and mechanical transmission can separate shaft speed from the frequency command.
Endpoint and linearity verification
Test three positions before returning the machine to service. The midpoint check catches reversed wiring, incorrect endpoint pairs, and nonlinear response that an endpoint-only test can miss.
| Potentiometer position | Expected input | Expected command | Diagnostic meaning |
|---|---|---|---|
| Minimum | 0 V |
40 Hz |
A higher command indicates offset or incorrect low-point scaling; a lower command indicates that another limit or scaling stage is active. |
| Midpoint | Approximately 5 V
|
Approximately 45 Hz
|
A large deviation points to wiring, potentiometer taper, analog calibration, or non-linear scaling. |
| Maximum | 10 V |
50 Hz |
A lower result points to insufficient input voltage or an additional upper restriction. |
If the displayed command pauses during part of the rotation, measure the analog voltage at the drive input while moving the control slowly. A smoothly changing voltage with a stationary frequency display places the fault in source selection, scaling, filtering, or another drive limit. A voltage that pauses or jumps places it in the potentiometer, supply, wiring, or terminal connection.
Recurring scaling pitfalls
Reversed potentiometer end connections make frequency decrease as the knob turns toward maximum. Swapping the two end connections corrects direction; keep the wiper on the analog-input terminal. Verify terminal identity from the drive wiring information before moving conductors.
A measured endpoint below 10 V prevents the reference from reaching the configured high coordinate. Check the reference supply, common conductor, wiper voltage, and terminal voltage under connected conditions. Electrical noise usually appears as an unstable command rather than a fixed dead band; inspect routing and grounding when voltage or frequency fluctuates at a stationary knob position.
An additional frequency limit can override correct analog scaling. If measured input voltage and the configured transfer function agree but the displayed command does not, inspect the active command source, limit functions, and analog-input diagnostic value rather than changing the endpoint percentages repeatedly.
FAQ
Why does the ПЧВ-1 potentiometer stop changing frequency at 40 Hz?
F01.13 = 40 Hz clamps the output while the analog input continues through the unused portion of its range. Set F01.13 = 0 and map 0 V to 80% instead.
Why does 0 V need to equal 80%?
The maximum is 50 Hz, and 40/50 = 0.8. Assigning 80% to the low analog point makes minimum potentiometer voltage command 40 Hz.
Why does the midpoint need to read about 45 Hz?
The configured relationship is linear from 0 V = 40 Hz to 10 V = 50 Hz. Half-scale input, approximately 5 V, therefore commands approximately 45 Hz.
Why does the drive still fail to reach 50 Hz after scaling?
Measure the input at maximum rotation and confirm that it reaches 10 V. If it does, inspect the active frequency source and any additional upper limit; if it does not, troubleshoot the potentiometer supply, wiring, and terminals.
When should I stop troubleshooting and contact official support?
Stop and escalate to the manufacturer's official support channel when the drive's analog diagnostic disagrees with a verified terminal measurement, the listed parameters are unavailable, or saved values do not remain active. Provide the complete parameter record, measured voltages at minimum, midpoint, and maximum, and the displayed frequency command at each point.