5.0   TESTING

5.1      LOW VOLTAGE CIRCUIT BREAKER TEST DATA SHEET

A Low Voltage Circuit Breaker Data Sheet should be filled out on every rebuilt circuit breaker. Test Data Sheets need to be completely filled out, and in particular circuit breaker name plate data, job number, curve specs, test results, date and technician name. If a technician has a question on the Low Voltage Circuit Data Sheet or question on how to perform a test then he should consult his/her supervisor.

5.2      MEGGER INSULATION TESTING

Megger Insulation Test – This test is required on all Low Voltage Circuit Breakers. This test is designed to insure that the breaker has adequate insulation. Test results can vary depending on weather conditions, but in most cases a test result of 100 mega ohms or higher is satisfactory for a rebuilt 480V circuit breaker. Test should be conducted from each phase to phase, phase to ground, and line to load. These test results should be recorded on the Low Voltage Circuit Breaker Data Sheet and attached to the job sheet.

5.3      CONTACT RESISTANCE TEST

Contact Resistance Test (Ductor Test) – This test is required on all low voltage circuit breakers and designed to insure that the circuit breaker has solid and equal contact surfaces on each phase. Compare resistance to adjacent poles and similar breakers. Investigate any deviations of more than twenty percent (20%).

5.4      ELECTRICALLY OPERATED BREAKERS

Electrically operated circuit breakers should be tested by means of applying voltage at the secondary disconnects and charging the circuit breaker charging motor (if stored energy mechanism), closing the circuit breaker from the secondary disconnects, and tripping the circuit breaker from the secondary disconnects. Verify operation of the Y relay. Also test any auxiliary contact circuits, under voltage devices, and bell alarms from the secondary disconnects. Test the blown fuse device on fused breakers.

5.5      HIGH CURRENT INJECTION TESTING

High Current Injection Test – This test is required on all Low Voltage Circuit Breakers. This test insures the reliability of the circuit breakers trip units. Each circuit breaker’s trip units should function within a specified time frame at a specific overload. It is customary to test a circuit breaker’s long time function at 300% of the breakers normal load rating and short time function at 150% of its overload rating. Instantaneous is determined by increasing the current level on the test set, using the run-up or pulse method, and injecting momentary current until the breaker trips. Clearing time should be within 20% of determined instantaneous setting. Determine ground fault time delay by primary current injection at 150% if applicable. Each manufacturer provides time current characteristic curves so as to determine if a circuit breaker’s trip units are operating as designed. Check the manufacturer’s curves for the specific circuit breaker being tested and record this information on the Low Voltage Circuit Breaker Data Sheet. Each circuit breaker should be tested on all functions and on all three phases.

5.6      CELL RACK-IN TEST

Rack-in Test – This test is required on all Low Voltage Circuit Breakers. This test insures the ability of the circuit breakers to be installed into the switchgear they were designed for. This test also insures the operability of all safety interlocks. The circuit breaker will be racked into the cubicle and various tests performed at each step in the racking process. Various factory tools and rails are also tested for compatibility.

 

5.7      QC INSPECTION

Initial and date the Process Control Form. Get inspector to initial and date the Process Control Form for testing.

1.0   INITIAL TEST AND INSPECTIONS

1.1      REQUIRED PROJECT PROCEDURES

The tech should start the job by reviewing the Work Order and then completing the Planning Work Sheet with the work leader or supervisor. The tech should post the Work Order with supporting technical information, a Process Control Form, and a Material Transfer Form at his/her workstation.

 

1.2      LOW VOLTAGE BREAKER DOCUMENTATION

A Low Voltage Circuit Breaker Data Sheet should be completed prior to disassembly. High current testing is not required unless the trip units are to be reused. Megger testing is required on all breakers to determine the initial condition of the pole pieces and insulators.

 

1.3      VISUAL INSPECTION OF EQUIPMENT

Remove the circuit breaker arc chutes and phase barriers to perform a complete visual inspection of moving main and arcing contacts, and stationary main and arcing contacts. Make any comments on the Low Voltage Circuit Breaker Data Sheet as to the general condition.

 

1.4      MECHANISM INSPECTION

Operate breaker manually, closing and tripping, inspecting and operate for proper contact wipe, worn or broken mechanism parts. Make any comments on worn or broken parts on the Low Voltage Circuit Breaker Data Sheet.

 

1.5      ELECTRICAL CONTROL INSPECTION

Verify that the proper schematic or wiring diagram is available for the breaker. Operate the circuit breaker electrically if possible, inspecting for proper operation of all auxiliary electrical devices, such as secondary disconnects, auxiliary switches, closing motors or solenoids, closing relays and tripping coils for defects. If unable to operate circuit breaker electrically, inspect all electrical components separately for proper operation recording any deficiencies on the Low Voltage Circuit Breaker Data Sheet and report to supervisor.

 

1.6      ELECTRICAL PARTS REPLACEMENT

Any parts needed, should be highlighted on the IT&I Parts Required Form and given to Inventory Control requesting these parts. When the parts are provided, the tech should log the parts on the Material Transfer Form.

 

1.7      QUALITY CONTROL C INSPECTION

Initial and date the Process Control Form. Get inspector to initial and date the Process Control Form for initial inspection.