ABB ACH550 Error 4021: START ENABLE 1 VIBRATION SWITCH FIRESTAT FREEZESTAT OVERPRESSURE VIBRATION TRIP SMOKE ALARM SAFETY OPEN LOW SUCTION PRES

AC drive · taken from the manufacturer’s manual, pages cited

Alarm code4021

START ENABLE 1 alarm happens when a start command is given but the RUN Enable condition is not satisfied. The manual's first action is: “Run Enable condition is not satisfied. Bad 24v supply Bad digital input 24 V common is not tied to Digital input common on bypass when using external 24 v supply Check 24 Volts on RBCU unit Check for 24 volts on respective DI when condition is satisfied Check Parameter 0103 For status of digital input”

Model
ABB ACH550
Display shows
4021
Type
Alarm code
Source
Manual p. 74

What 4021 means

START ENABLE 1 VIBRATION SWITCH FIRESTAT FREEZESTAT OVERPRESSURE VIBRATION TRIP SMOKE ALARM SAFETY OPEN LOW SUCTION PRES p. 74

Common causes

  • Alarm will occur when start order is given and the "RUN Enable" is not present p. 74

What to do

  1. Run Enable condition is not satisfied. Bad 24v supply Bad digital input 24 V common is not tied to Digital input common on bypass when using external 24 v supply Check 24 Volts on RBCU unit Check for 24 volts on respective DI when condition is satisfied Check Parameter 0103 For status of digital input p. 74

Before you service the product, read the safety instructions in the manual p. 2.

If 4021 is still not resolved

  • contact the factory or your local Authorized Service Center for repair or replacement. p. 2
    “Never attempt to repair a malfunctioning ACH550; contact the factory or your local Authorized Service Center for repair or replacement.”
Open the manual at page 74 All ACH550 error codes Manual details & download

This page summarises what the manufacturer’s manual says about 4021; each statement links to the page it comes from, and quoted lines are copied word for word. It is not a substitute for the manual or for a qualified installer. ManualLib is not affiliated with ABB. Found a mistake? Report an error.