Eaton 380 VCP-Wind Instructions For The Use, Operation And Maintenance

Contents

Page 18 I.B. 70A2580H02Effective November 20125-3.3 CLOSING OPERATIONFigure 5-2 shows the position of the closing cam andtripping linkage. Note that in Figure 5-2a in which thecircuit breaker is open and the closing springs aredischarged, the trip “D” shaft and trip latch are in theunlatched position.Once charged, the closing springs can be released toclose the circuit breaker by moving the spring releaselatch out of the way. This is done electrically or manuallyby depressing the spring release lever, which turns thespring release latch out of the way of the closing stoproller. The force of the closing spring rotates the camshaft through the spring cranks. The closing cam, beingattached to the cam shaft, in turn rotates the pole shaftthrough the main link to close the circuit breaker.In Figure 5-2c the linkage is shown with the circuitbreaker in the closed position before the closing springshave been recharged. Interference of the trip “D” shaftwith the trip latch prevents the linkage from collapsing,and the circuit breaker is held closed.Figure 5-2d shows the circuit breaker in the closedposition after the closing springs have been recharged.Note that the spring charging rotates the closing cam byone half turn. Since the cam surface in contact with themain link roller is cylindrical in this region, the springcharging operation does not affect the mechanismlinkage.Since the primary contacts are completely enclosed inthe vacuum interrupter and not adjustable in any way, a“Slow Close” capability is not provided with VCP-Windcircuit breakers.5-3.4 TRIPPING OPERATIONWhen the trip “D” shaft is turned either by the trip buttonor trip coil, all links return to the original “open” conditionshown in Figure 5-2a.5-4 CONTROL SCHEMESThere are two basic control schemes for 38kV VCP-Wind circuit breakers, one for DC control and one forAC control voltages (Figures 5-4 and 5-5). There may bedifferent control voltages or more than one trippingelement, but the principal mode of operation is asfollows:As soon as the control power is applied, the springcharging motor automatically starts charging theclosing springs. When the springs are charged, themotor cut off LS1/bb switch turns the motor off. Thecircuit breaker may be closed by making the controlswitch close (CS/C) contact. Automatically uponclosing of the circuit breaker, the motor starts chargingthe closing springs. The circuit breaker may betripped any time by making the control switch trip(CS/T) contact.Note the position switch (PS 1) contact in the springrelease circuit in the scheme. This contact remainsmade while the circuit breaker is being leveredbetween the TEST and CONNECT positions.Consequently, it prevents the circuit breaker fromclosing automatically, even though the control closecontact (CS/C) may have been made while the circuitbreaker is levered to the CONNECT position.The position switch (PS2) contact is in the motorcircuit. It prevents the motor from starting until the fullyCONNECT position is reached and the secondarycontacts are firmly engaged.When the CS/C contact is made, the SR closes thecircuit breaker. If the CS/C contact is maintained afterthe circuit breaker closes, the Y relay is picked up.The Y/a contact seals in Y until CS/C is opened. TheY/b contact opens the SR circuit, so that even thoughthe circuit breaker would subsequently open, it couldnot be reclosed before CS/C was released andremade. This is the anti-pump function.5-4.1 TIMINGThe opening and closing times for the circuit breakersvary depending upon the control voltage and the powerrating. Maximum values for 38kV VCP-Wind circuitbreakers are shown in Table 5.1.5-4.2 SECONDARY DISCONNECTSThe VCP-Wind drawout circuit breaker control wiringis arranged to connect two standard 30 point maleplugs with corresponding switchgear compartmentmounted female plugs.Drawout circuit breakers utilize fixed mounted maleplugs located on the top left portion of the circuitbreaker. The two 30 point plugs are mounted in aside-by-side arrangement (Figure 5-6).