Eaton VCP-W Series Instructions For Installation/operation/maintenance/servicing

Also see for 120VCP-W25: Installation, operation and maintenance Instructions for installation, operation and maintenance

Contents

51Instruction Booklet IB131006ENEffective March 2019Instructions for installation,operation, and maintenance of typeVCP-W vacuum circuit breakersEATON www.eaton.com6.4 Vacuum interrupter integrity testVacuum interrupters used in Type VCP-W vacuum circuit breakerelements are highly reliable interrupting elements. Satisfactoryperformance of these devices is dependent upon the integrity of thevacuum in the interrupter and the internal dielectric strength. Bothof these parameters can be readily checked by a one minute AC highpotential test. Refer to Table 24 for the appropriate test voltage.During this test, the following warning must be observed.m WARNINGAPPLYING ABNORMALLY HIGH VOLTAGE ACROSS A PAIR OF CONTACTSIN VACUUM MAY PRODUCE X-RADIATION. THE RADIATION MAYINCREASE WITH THE INCREASE IN VOLTAGE AND/OR DECREASE INCONTACT SPACING. X-RADIATION PRODUCED DURING THIS TESTWITH RECOMMENDED VOLTAGE AND NORMAL CONTACT SPACINGIS EXTREMELY LOW AND WELL BELOW MAXIMUM PERMITTED BYSTANDARDS. HOWEVER, AS A PRECAUTIONARY MEASURE AGAINSTPOSSIBILITY OF APPLICATION OF HIGHER THAN RECOMMENDED VOLTAGEAND/OR BELOW NORMAL CONTACT SPACING, IT IS RECOMMENDED THATALL OPERATING PERSONNEL STAND AT LEAST 13 FEET (4 METERS) AWAYIN FRONT OF THE BREAKER ELEMENT.With the breaker element open, connect all top primary studs (bars)together and to the high potential machine lead. Connect all bottomstuds together and ground them along with the breaker frame. Startthe machine at zero potential, increase to appropriate test voltageand maintain for one minute.A successful withstand indicates that all interrupters have a satisfac-tory vacuum level. If there is a break-down, the defective interrupteror interrupters should be identified by an individual test and replacedbefore placing the breaker in service.m WARNINGAFTER THE HIGH POTENTIAL IS REMOVED, AN ELECTRICAL CHARGEMAY BE RETAINED BY THE VACUUM INTERRUPTERS. FAILURE TODISCHARGE THIS RESIDUAL ELECTROSTATIC CHARGE COULD RESULT INAN ELECTRICAL SHOCK. ALL SIX PRIMARY TERMINALS AND THE CENTERRING OF EACH VACUUM INTERRUPTER OF THE CIRCUIT BREAKER SHOULDBE GROUNDED TO REDUCE THIS ELECTRICAL CHARGE BEFORE COMING INCONTACT WITH THE PRIMARY CIRCUIT.To avoid any ambiguity in the AChigh potential test due to leakage ordisplacement (capacitive) current, the test unit should have sufficientvolt-ampere capacity. It is recommended that the equipment becapable of delivering 25 milliamperes for one minute.ONLY AC HIGH POTENTIAL TESTS ARE RECOMMENDED.EATON DOES NOT RECOMMEND DC POWER FREQUENCYWITHSTAND VOLTAGE TEST.Table 24. Test voltage (insulation and vacuum integrity).Breaker ratedmaximum voltage Vacuum interrupter integrity test voltageAC 60 HzUp to and including 5 kV 15 kV7.5 kV - 17.5 kV 27 kV24 kV and 27 kV 45 kVThe current delivery capability of 25 mA AC and 5 mA DC applywhen all three vacuum interrupters are tested in parallel. If indi-vidual vacuum interrupters are tested, current capability may be onethird of these values.m CAUTIONSOME DC HIGH POTENTIAL UNITS, OPERATING AS UNFILTERED HALF-WAVE RECTIFIERS, ARE NOT SUITABLE FOR USE TO TEST VACUUMINTERRUPTERS BECAUSE THE PEAK VOLTAGE APPEARING ACROSS THEINTERRUPTERS CAN BE SUBSTANTIALLY GREATER THAN THE VALUE READON THE METER.6.5 Contact erosion and wipeSince the contacts are contained inside the interrupter, they remainclean and require no maintenance. However, during high currentinterruptions there may be a minimum amount of erosion from thecontact surfaces. Maximum permitted erosion is about 1/8 in.(3.18 mm). To determine contact erosion, close the breaker andobserve the vacuum interrupter moving stem from the rear of thebreaker. If the mark on each stem is visible, erosion has not reachedmaximum value thus indicating satisfactory contact surface of theinterrupter. If the mark is not visible, the pole unit assembly must bereplaced (Figures 27 and 28).The adequacy of contact wipe can be determined by observing thevacuum interrupter side of the operating rod assembly on a closedcircuit breaker. Figure 29 shows the procedure for determining thecontact wipe. If the wipe is not adequate, the vacuum interrupterassembly (pole unit) must be replaced. A field adjustment is notpossible. Refer to paragraph 7.3.2 for a replacement procedure.m WARNINGFAILURE TO REPLACE A POLE UNIT ASSEMBLY, WHEN CONTACT EROSIONMARK IS NOT VISIBLE OR WIPE IS UNSATISFACTORY, WILL CAUSE THEBREAKER TO FAIL TO INTERRUPT AND THEREBY CAUSE PROPERTYDAMAGE OR PERSONAL INJURY.