A drive that runs directly to maximum speed when the increase input is activated is not producing the requested stepped-speed behavior. The first decision is whether the application needs a continuously adjustable raise/lower reference or discrete preset frequencies. These are different control modes and require different configurations.
Separate Raise/Lower Control from Preset Speeds
| Required behavior | Function to select | Input response |
|---|---|---|
| Frequency changes continuously while an input remains active and holds when released | Raise/lower speed, also described as a motorized potentiometer | Increase raises the reference; decrease lowers it |
| Each input condition selects a defined frequency step | Preset speeds | The active input combination selects SP1, SP2, or another configured preset |
Raise/lower control does not inherently advance through predefined frequency steps. If each pushbutton action must move between fixed operating points, use preset speeds or model-specific step logic instead.
Why the Drive Goes Directly to Maximum Speed
The reported configuration assigns digital inputs to increase speed and selects raise/lower control as reference 2. If the increase command remains active, the reference continues rising until it reaches the configured upper frequency limit. This can appear to be an immediate jump when the expected behavior was one fixed increment per button action.
The evidence does not establish the input timing, acceleration settings, wiring state, or complete reference-selection logic. Therefore, treat a maintained increase signal, an unintended input state, and incorrect selection between the primary and secondary references as checks rather than confirmed causes.
Choose the Required Control Sequence
- Define the intended response precisely: continuous movement while a button is held, or one discrete transition per button operation.
- For continuous adjustment, retain raise/lower control and set the required minimum and maximum frequency limits. Confirm that releasing both commands holds the current reference.
- For discrete operating points, configure preset speeds such as SP1 and SP2 and assign the digital inputs or input combinations that select them.
- Do not combine the two concepts unless the drive manual explicitly documents a model-specific arrangement for stepped raise/lower operation.
Check Commands, Limits, and Reference Selection
Monitor the drive input states while operating both levels of the pushbutton. Verify that only the intended increase or decrease command becomes active and that neither command remains asserted after release. Then confirm that reference 2 is actually selected under the tested operating condition.
For raise/lower operation, verify the configured lower and upper frequency limits because they bound the adjustable reference. For preset-speed operation, verify every required preset value and its input-selection condition. The available functions and configuration method vary by drive model, so use the programming manual for the installed unit rather than transferring settings from another drive family.
Verify the Result
| Test | Expected raise/lower result | Expected preset-speed result |
|---|---|---|
| Activate increase | Reference rises while the command remains active | Drive selects the assigned higher preset |
| Release the controls | Reference remains at its current value | Result follows the configured preset-selection state |
| Activate decrease | Reference falls while the command remains active | Drive selects the assigned lower preset |
| Reach a configured limit | Reference stops at the minimum or maximum frequency | Drive runs at the selected preset value |
Repeat the test while observing commanded frequency and digital-input status. The configuration is correct only when the displayed reference follows the selected control model and does not run to the upper limit from an unintended maintained command.
FAQ
Why does the Altivar drive go to maximum speed when I press increase?
In raise/lower mode, a maintained increase command raises the reference until it reaches the configured maximum frequency. Check the live input state, button behavior, frequency limits, and active reference selection.
Does plus/minus speed move through preset frequency steps?
Not inherently. Raise/lower control changes frequency while the corresponding input is active; use preset speeds such as SP1 and SP2 when the application requires defined operating steps.
How do I make a VFD hold speed after releasing the button?
Select raise/lower speed control, assign the increase and decrease inputs, and configure the minimum and maximum frequency limits. Verify that releasing both inputs leaves the commanded reference unchanged.