The ABB TA75DU32-20 is a thermal overload relay rated 22-32 A with trip class 20, designed to protect motors against overload and phase failure in the main circuit. Class 20 means the relay will trip within 20 seconds at 7.2× the current setting — a standard protection curve for general-purpose induction motors driving pumps, fans, and conveyors where moderate start times are expected.
Key features and how they matter
The relay includes temperature compensation, a trip-free mechanism, and selectable automatic or manual reset — the trip-free design prevents the contacts from being held closed during a fault, which is critical for safety in unattended installations. It provides a normally closed trip contact and a normally open signal contact, so the control circuit can both interrupt the contactor coil and send a remote alarm without additional interposing relays. Built-in stop and test functions allow manual verification of the trip mechanism during commissioning or periodic inspection without needing to simulate a motor fault.