ABB EK550 AC Contactor Product Description

Overview

ABB EK550 is a heavy‑duty AC contactor of the ABB EK series, rated 550 A main current for switching AC and DC loads. This ABB contactor is widely used for transformer feeder, large motor, capacitor bank and low‑voltage distribution circuit switching. EK550 has multiple pole variants (3‑pole / 4‑pole, such as EK550‑40‑11 4P version) and various coil voltage options; it is a common spare for industrial and marine switchgear retrofitting and replacement of legacy EK contactor systems.

Features

ABB EK550 contactor adopts large‑capacity silver alloy main contacts and optimized arc extinguishing chamber for reliable breaking under heavy load. This ABB contactor supports AC‑3 motor duty and AC‑1 resistive continuous duty, and can also be used for DC switching with derating. EK550 can be fitted with auxiliary contact blocks, thermal overload relays and mechanical interlock accessories for motor protection and interlock logic. The coil has wide voltage options (AC 24~690 V, DC 24~220 V). This contactor complies with IEC 60947‑4‑1 and obtains marine certifications for shipboard switchboard application.

Specs

ABB EK550 heavy duty contactor

• Brand: ABB

• Series: EK

• Model: EK550

• Rated thermal current Ith: 550 A

• Rated operational voltage Ue: Up to 690 V AC

• Pole configuration: 3P / 4P (EK550‑40‑11 is 4‑pole)

• Coil voltage: Multiple options (AC / DC)

• Standard: IEC 60947‑4‑1

• Mounting: Screw mounting on backplate

• Accessories: Auxiliary contacts, overload relay, mechanical interlock

Principle

ABB EK550 contactor closes the main contacts when the coil receives the rated control voltage. The electromagnetic coil generates magnetic force to pull in the armature and drive the contact mechanism, turning on the main power circuit. When coil power is removed, the return spring opens the main contacts to cut off the load circuit. Auxiliary contacts synchronously switch state to feed back run/standby signal to PLC or protection circuit. The arc chamber quenches the arc generated during contact opening to prevent contact ablation.

Applications

ABB EK550 contactor is deployed in factory auxiliary power rooms, marine low‑voltage switchboards, water treatment plants, large pump and fan control cabinets and capacitor compensation cabinets. This ABB contactor is used for switching large induction motors, transformer secondary loads and bus sections. EK550 fits power cabinet overhaul and spare replacement of legacy ABB EK series heavy contactors.

Installation & Maintenance Notes

Follow official ABB EK series contactor hardware manuals during installation of EK550. Apply specified torque for main cable terminals to avoid overheating. Confirm coil voltage before powering on; mismatched coil voltage will burn the coil. Check contact surface condition, coil temperature and auxiliary wiring regularly, especially in high‑humidity marine environments. Confirm exact model EK550, pole number and coil voltage code before spare‑part swap‑out.