ACB Repairs & Testing Engineer

ACB Repair & Testing Engineer

Department: Electrical Service & Repair

Location: UAE

Job Purpose

We are looking for an experienced ACB Repair & Testing Engineer responsible for inspection, troubleshooting, repair, maintenance, testing, and commissioning of low-voltage Air Circuit Breakers (ACBs).

The candidate should have strong hands-on experience with ACB mechanical mechanisms, electronic trip units, protection systems, control circuits, closing/tripping mechanisms, and primary and secondary injection testing.

Experience working with multiple brands such as ABB, Schneider Electric, Siemens, Mitsubishi, Terasaki, Eaton and LS will be preferred.

Key Responsibilities

• Inspect, troubleshoot, repair, overhaul, and test ACBs ranging approximately from 400 A to 6300 A.

• Diagnose electrical, electronic, and mechanical faults in ACBs.

• Carry out complete dismantling, cleaning, inspection, servicing, lubrication, reassembly, and functional testing.

• Inspect and assess main contacts, arcing contacts, arc chutes, operating mechanisms, springs, latches, interlocks and racking mechanisms.

• Troubleshoot electronic trip units and protection systems, including Long-Time, Short-Time, Instantaneous and Ground-Fault protection.

• Test and troubleshoot closing coils, shunt-trip coils, undervoltage releases, spring-charging motors, auxiliary contacts and indication circuits.

• Perform primary current injection testing and verify actual breaker trip performance.

• Perform secondary injection testing and protection-trip verification where applicable.

• Conduct contact resistance / micro-ohm measurements for all poles.

• Perform insulation resistance and dielectric tests according to manufacturer requirements.

• Measure and evaluate opening time, closing time and pole synchronization using breaker timing equipment.

• Carry out manual and electrical OPEN/CLOSE/TRIP functional tests.

• Test draw-out ACB service/test/disconnected positions and mechanical/electrical interlocks.

• Interpret electrical schematics, ACB wiring diagrams, manufacturer manuals and trip curves.

• Identify defective components and prepare required spare-parts lists.

• Perform pre-repair and post-repair testing and compare results.

• Prepare professional inspection, repair and final test reports with measured values and findings.

• Maintain traceable records of test equipment and ensure instruments remain within calibration.

• Attend customer sites for troubleshooting, maintenance, testing and commissioning when required.

• Follow company safety procedures, LOTO requirements and electrical safe-working practices.

Technical Knowledge Required

The candidate should be familiar with:

ACB Brands

ABB Schneider MasterPact Siemens SENTRON Mitsubishi Terasaki Eaton LS and similar industrial ACBs.

Testing Equipment

• Primary current injection test sets

• Secondary injection / trip-unit test equipment

• 100 A micro-ohm/contact resistance tester

• Insulation resistance tester

• Circuit breaker timing analyzer

• Hi-Pot tester

• Digital multimeter

• Clamp meter

• Variable AC/DC power supplies

• Thermal imaging equipment

Protection Functions

• L – Long-Time

• S – Short-Time

• I – Instantaneous

• G – Ground Fault

• Protection curves and trip-time interpretation

Qualification & Experience

Education: Diploma / ITI / Bachelor's Degree in Electrical or Electrical & Electronics Engineering.

Experience: Preferably 5+ years of hands-on experience in ACB servicing, repair and testing.

Candidates with strong practical ACB repair experience may be considered even without a bachelor's degree.

Essential Skills

The candidate must be capable of independently taking an ACB from:

Incoming Inspection → Fault Diagnosis → Dismantling → Repair → Reassembly → Adjustment → Electrical Testing → Primary/Secondary Injection → Final Functional Test → Test Report

Strong troubleshooting ability is more important than experience limited to routine preventive maintenance.

Preferred Candidate

Preference will be given to candidates who have previously worked in:

ACB manufacturer service centers, switchgear service companies, LV switchgear workshops, circuit-breaker repair facilities, power-distribution maintenance companies, or industrial electrical service organizations.

Experience repairing electronic trip units and control circuits at component/board level will be a significant advantage.

Safety Responsibilities

The engineer must follow appropriate electrical safety practices including LOTO, isolation and voltage proving, proper earthing, use of calibrated equipment and PPE, and safe operation of high-current primary injection equipment.

Important Recruitment Requirement

For this position, I recommend not hiring someone whose experience is only ACB installation or preventive maintenance.

The person should have genuine repair-shop experience and should be able to diagnose why an ACB doesn't close, doesn't trip, trips incorrectly, fails primary injection, has high contact resistance, has a charging mechanism fault, has an interlock/racking problem, or has an electronic trip-unit fault.

Work Location: In person