Description

The ABB UA50 is a surge suppressor for ABB AF09 to AF38 series contactors, designed to suppress inductive voltage transients generated when the contactor coil is de-energised in control circuits operating at 100–250 V AC/DC. The suppression of coil de-energisation spikes is essential in installations where sensitive control devices, PLC I/O modules, or electronic relays share the same control wiring, as uncontrolled voltage spikes can cause false triggering, component damage, or premature failure of the control circuit devices. The UA50 provides an effective and integrated solution for this requirement within ABB’s AF-Line contactor system.

The UA50 mounts directly onto the AF09–AF38 contactor coil terminals using a snap-on connector that requires no wiring or tools, ensuring correct and reliable connection. The varistor-based suppression element clamps the peak transient voltage to a safe level, dissipating the stored coil energy during de-energisation and preventing voltage spikes from propagating back into the control circuit. Rated for 100–250 V AC/DC control circuits, the UA50 covers the widest range of standard industrial control voltages used with these contactors.

The UA50 is used in industrial automation panels, motor control centres, building management systems, and process control installations where AF09–AF38 contactors are operated from 100–250 V control circuits. Coil surge suppression is particularly important in panels where contactors share control wiring with PLCs, temperature controllers, or other microelectronic devices that may be susceptible to inductive transients. The UA50 provides a low-cost, easily applied means of compliance with best-practice recommendations for contactor coil protection and control circuit reliability in IEC 60947-compliant motor control systems.