AirCompDX

VFD hand/auto: run permissive, remote start, speed reference

24 VDC drive control, 4–20 mA analog reference

All wiring guides

VFD hand/auto: run permissive, remote start, speed reference

Terminal-by-terminal wiring for a drive that runs from a keypad in HAND and from a controller's dry contact plus 4–20 mA reference in AUTO, with fault and run feedback returned to the controller.

VFD-driven rotary screwsRetrofit VFDs on existing startersBooster and vacuum packages
STO / safetyS1-S224 Vdrive supplyDI1run fwdDI2hand/autoAI1 +4–20 mA refAI COManalog commonRO1fault relayControllerdry contacts
Step 1 of 7
Step 1

Safety / STO first

From
E-stop and safety chain
To
Drive STO terminals S1-S2 (or the enable input)

Conductor: 18 AWG

Land the hard-wired safety chain on the drive's Safe Torque Off inputs. If the drive has no STO, keep a line contactor ahead of it that the safety chain drops out. Never rely on a digital run input as a safety.

Verify before moving on
  • Drive shows STO/safety fault with the chain open
  • Both STO channels open together

Aux contacts & feedback

  • Keep motor leads in their own conduit — running them with the 4–20 mA pair induces reference noise and nuisance trips.
  • If the drive replaces a starter, the old starter's aux contacts can still feed run lights: drive the coil of an interposing relay from the drive's run relay.
  • Record the parameter set after commissioning; a drive swapped in without the parameter file is a common repeat call.

Before you land a wire

  • Bus capacitors stay charged after power-off — wait for the drive's stated discharge time and verify DC bus voltage before touching terminals.
  • Never megger a motor with the drive still connected.
  • Do not switch the motor contactor while the drive is running unless the drive is rated for output switching.

Reference only. Terminal numbers vary by manufacturer — confirm against the actual device drawing and follow NEC/NFPA 79 and your site's electrical safety program.