Description

The ABB UA75 is a surge suppressor accessory for ABB AF40 to AF96 series contactors, providing protection of the coil circuit against inductive voltage transients at 24–48 V AC/DC control voltage. Larger contactors in the AF40–AF96 range have proportionally larger coils with greater stored magnetic energy, and the voltage spikes generated on de-energisation can be more significant than those from smaller contactors. The UA75 is specifically rated and dimensioned for the higher energy suppression requirements of these larger AF-Line contactors, ensuring effective protection of both the contactor coil and the control circuit devices at 24–48 V.

The UA75 mounts directly onto the AF40–AF96 contactor coil terminals using the snap-on interface provided by ABB’s coil accessory mounting system, ensuring correct and secure connection without additional wiring. The varistor suppression element absorbs the inductive energy from the de-energising coil and clamps the peak voltage to a level safe for the coil insulation and control circuit components. This integrated mounting approach ensures the suppressor is always correctly installed and eliminates the potential for wiring errors associated with separate RC or varistor suppressor units.

The UA75 is an important accessory for control panels using ABB AF40–AF96 contactors in automated industrial systems, motor control centres, building services controls, and process automation applications at 24–48 V control voltage. It is recommended by ABB as a standard accessory wherever ABB AF-Line contactors are controlled by PLC outputs, solid-state relays, or other electronic devices that may be affected by inductive transients. Specifying the UA75 as a standard component in AF40–AF96 contactor applications is an effective and low-cost way to improve control circuit reliability and protect electronic control equipment investment.