VFD Terminal Functions: Power, Motor, Control and STO
Identify drive power, motor, analog, digital and safety terminal groups using the ATV320 manual as a scoped example, then record the actual drive configuration.
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Separate the terminal groups
Group drive terminals by function before reading individual labels. A terminal label is meaningful only within the exact drive model, frame and manual revision. Schneider Electric ATV320 documentation is the named example here; the group labels are not a universal drive pinout.
| Group | ATV320 example labels / role | What must be checked |
|---|---|---|
| AC supply | R/L1, S/L2, T/L3 on applicable versions. | Single/three-phase variant, rated supply and actual terminal diagram. |
| Motor output | U/T1, V/T2, W/T3. | Drive-to-motor output; never infer these are supply-input terminals. |
| Analog control | AI inputs and associated reference/common terminals. | Configured current/voltage mode, range, polarity and common relationship. |
| Digital control | Logic inputs and control supply terminals. | Source/sink configuration, assigned functions and external supply arrangement. |
| Safety function | STO and its associated circuit. | Exact safety manual, validated circuit and required performance. |
| DC link / braking | Dedicated bus or braking terminals where provided. | Model-specific resistor/bus instructions and stored-energy restrictions. |
Trace a command without inventing a pinout
Start with the actual frame and voltage variant in the ATV320 installation manual. Then use the programming documentation to identify the assigned run command, speed reference and control mode. Hardware names alone cannot reveal whether a digital input is configured for forward run, a preset speed or another function.
- Record complete model number and manual revision.
- Mark supply, motor, control and safety areas on the manufacturer drawing.
- Record the configuration assigned to each used input or output.
- Retain the control-supply and common-reference arrangement.
Keep safety and isolation distinct
Safe Torque Off inhibits torque production within its documented function. It is not electrical isolation and does not establish that the motor terminals or DC link are safe to touch. Use the actual equipment energy-control procedure and the manufacturer discharge/verification instructions.
This reference supplies no generic terminal bridging or commissioning sequence. Read motor identification in motor nameplates, control signal roles in current-loop wiring, and retain document references in the job card.
For the separate numerical task, use VFD and motor worksheet. Use the equipment data identified above as inputs within each tool’s stated scope.