Eaton VR+ Series Instruction Book

Contents

13Instruction Book IB182923EN September 2018 www.eaton.comAMH-4.76-VR+VR-Series+ Replacement Circuit Breakerm DANGERFAILURE TO REPLACE THE VACUUM INTERRUPTER ASSEMBLY WHENINDICATED BY THE CONTACT EROSION INDICATOR COULD CAUSE THECIRCUIT BREAKER TO FAIL, LEADING TO DEATH, SEVERE PERSONALINJURY, EQUIPMENT DAMAGE AND/OR IMPROPER OPERATION.4.1.3 CONTACT WIPE AND STROKEThe circuit breaker mechanism provides a fixed amount of motionto the operating rods connected to the moving stem of the vacuuminterrupter. The first portion of the motion, the stroke, is used toclose the vacuum interrupter contacts; the remainder of that motion,the wipe, is used to further compress the pre-loaded wipe spring.Contact stroke and wipe are related; contact wipe is the indicationof the force holding the vacuum interrupter contacts closed as wellas the energy available to hammer the contacts open with sufficientspeed for interruption. Stroke is the gap between the stationary andmoving contact of the vacuum interrupter when the circuit breakeris open. As the stroke increases due to contact erosion inside thevacuum interrupter, the wipe decreases. Although these changesare taking place as operations accumulate on the vacuum interrupter,field adjustment of the wipe or stroke are not necessary during thelifetime of the vacuum interrupter.m WARNINGTHERE IS NO PROVISION FOR IN-SERVICE ADJUSTMENTS OF CONTACTWIPE AND STROKE. ALL SUCH ADJUSTMENTS ARE FACTORY SET ANDSHOULD NOT BE ATTEMPTED IN THE FIELD.4.2 PHASE BARRIERSPhase barriers are sheets of insulation located between theinterrupter pole assemblies and on the sides of the breaker frame.The phase barriers are designed to isolate energized conductorcomponents in each phase from the adjacent phase and ground.m WARNINGALL PHASE BARRIERS MUST BE IN PLACE BEFORE PLACING THECIRCUIT BREAKER INTO SERVICE. FAILURE TO HAVE THEM IN POSITIONCAN CAUSE DEATH, SERIOUS PERSONNEL INJURY AND/OR PROPERTYDAMAGE.4.3 BUSHINGS AND DISCONNECTING CONTACTASSEMBLIESThe line and load bushing assemblies, which are the primarycircuit terminals of the circuit breaker, consist of six silver platedconductors. Solid stab type primary disconnecting contacts atthe ends of the conductors provide means for connecting anddisconnecting the circuit breaker to the bus terminals in theswitchgear compartment.4.4 STORED ENERGY MECHANISMThe spring-type stored energy operating mechanism is mountedon the circuit breaker frame and in the front of the circuit breaker.Manual closing and opening controls are at the front cover (FigureSet 3.3). They are accessible while the circuit breaker is in any of itsbasic installation positions. (See Section 5 in this manual)The mechanism stores the closing energy by charging the closingsprings. Spring charging is automatically accomplished when controlpower is applied to the circuit breaker secondary disconnect contact.When released, the stored energy closes the circuit breaker, chargesthe wipe and resets the opening springs. The mechanism may restin any one of the four positions shown in Figure 4.6 as follows:a. Circuit breaker open, closing springs discharged.b. Circuit breaker open, closing springs charged.c. Circuit breaker closed, closing springs discharged.d. Circuit breaker closed, closing springs charged.m DANGERKEEP HANDS AND FINGERS AWAY FROM CIRCUIT BREAKER’S INTERNALPARTS WHILE THE CIRCUIT BREAKER CONTACTS ARE CLOSED OR THECLOSING SPRINGS ARE CHARGED. THE CIRCUIT BREAKER CONTACTSMAY OPEN OR THE CLOSING SPRINGS DISCHARGE CAUSING CRUSHINGINJURY. DISCHARGE THE SPRINGS AND OPEN THE CIRCUIT BREAKERBEFORE PERFORMING ANY MAINTENANCE, INSPECTION OR REPAIR ONTHE CIRCUIT BREAKER.THE DESIGN OF THIS CIRCUIT BREAKER ALLOWS MECHANICAL CLOSINGAND TRIPPING OF THE CIRCUIT BREAKER WHILE IT IS IN THE ‘CONNECT’POSITION. HOWEVER, THE CIRCUIT BREAKER SHOULD BE CLOSEDMECHANICALLY ONLY IF THERE IS POSITIVE VERIFICATION THAT LOADSIDE CONDITIONS PERMIT. IT IS RECOMMENDED THAT CLOSING THECIRCUIT BREAKER IN THE ‘CONNECT’ POSITION ALWAYS BE DONE WITHTHE CUBICLE DOOR CLOSED. FAILURE TO FOLLOW THESE DIRECTIONSMAY CAUSE DEATH, SEVERE PERSONAL INJURY, EQUIPMENT DAMAGEAND/OR IMPROPER OPERATION.ELECTRICAL TRIPPING CAN BE VERIFIED WHEN THE CIRCUIT BREAKER ISIN THE ‘DISCONNECT / TEST’ POSITION.4.4.1 CLOSING SPRING CHARGINGFigure 4.5 shows schematic section views of the spring chargingparts of the stored energy mechanism.The major component of the mechanism is a cam shaft assemblywhich consists of a shaft to which are attached two closing springcranks (one on each end), the closing cam, drive plate, and a free-wheeling ratchet wheel.The ratchet wheel (6) is actuated by an oscillating ratchet lever(12) and drive pawl (10) driven by the motor eccentric cam. As theratchet wheel rotates, it pushes the drive plates which in turn rotatethe closing spring cranks and the closing cam on the cam shaft.The motor will continue to run until the limit switch “LS” contactdisconnects the motor.The closing spring cranks have spring ends connected to them,which are in turn coupled to the closing springs. As the cranksrotate, the closing springs get charged.The closing springs are completely charged, when the spring cranksgo over dead center and the closing stop roller (9) comes against thespring release latch (1). The closing springs are now held in the fullycharged position.The closing springs may also be charged manually as follows: Insertthe end of the maintenance tool into the manual charge socketopening and charge the closing springs by moving the handle upand down the full range of motion. When charging is complete theratchet will no longer advance and the spring charged / dischargedindicator displays ‘Charged’. (Figure Set 3.3). Any further motion ofthe maintenance tool will not result into advance of charging.4.4.2 CLOSING OPERATIONFigure 4.6 shows the positions of the closing cam and trippinglinkage for four different operational states. In Figure 4.6.a thecircuit breaker is open and the closing springs are not charged. Inthis state, the trip latch (8) is disengaged from the trip “D” shaft (9)(unlatched). After the closing springs become charged, the trip latchsnaps into the fully reset or latched position (Figure 4.6.b)The mechanism is a mechanically “trip-free” design. Trip-free isdefined in Section 4.3.4 (Trip-Free Operation).In normal operation the closing spring is charged by the springcharging motor, and the circuit breaker is closed electrically by theswitchgear control circuit signal to energize the spring release coil.Tripping is caused by energizing the trip coil through the controlcircuit.For maintenance inspection purposes the closing springs can becharged manually by using the maintenance tool and the circuitbreaker can be closed and tripped by pushing the “Push to Close”and “Push to Open” operators on the front cover.