Eaton W-VAC Series Instructions For Installation, Operation And Maintenance

Also see for 120W-VAC16: Instructions for installation, operation and maintenance

Contents

Instruction BookPage 33IB131009EN5-3.3 UNDERVOLTAGE TRIP DEVICEThe undervoltage trip device for all circuit breakers is anelectromechanical device that operates to open thebreaker at 35% or less of the voltage rating of the tripcoil. The device does not open the breaker at valuesabove 70% of the voltage rating of its trip coil. It mayoperate, however, to open the breaker when the voltageacross the trip coil is greater than 35%, but less than70% of the voltage rating of its trip coil. The breaker canbe closed as long as the voltage to the trip coil is main-tained at 85% or above the rated level. The undervolt-age trip device is available only as an instantaneoustype with rated voltages of 48VDC, 125VDC, and250VDC.For a basic understanding of the operation of the under-voltage trip device refer to Figure 5-8, the followingoperation description and the specific items identified inthe Figure 5-8:1.) With the breaker closed and sufficient voltage on theUndervoltage Trip Device coil, the moving clapper (1) isheld to the stationary yoke (2) by the magnetic forceproduced by the coil (3) against the extension springs(4) pulling the moving clapper apart from the yoke.2.) The moving clapper is connected to the mechanismTrip D Shaft Lever (5) by a slotted link (6).3.) When the voltage to the Undervoltage Trip Coil goesdown as described earlier, the extension springs forceovercomes the reduced magnetic force and pulls themoving clapper up. The slotted link in turn upsets theTrip D Shaft and the breaker trips open.4.) As the breaker opens, the reset lever (8) connectedto the pole shaft lever (7) operates to reset the movingclapper. As long as the breaker remains open, the resetlever holds down the moving clapper to the yoke.5.) When the breaker closes, the reset lever movesaway from moving clapper. If the Undervoltage TripDevice coil has at least 85% of the rated voltageapplied, the moving clapper is held to the yoke by themagnetic force,even though the reset lever has movedup.5-4 INTERLOCKSNEVER DISABLE OR DEFEAT ANY INTERLOCKS.HAZARDOUS VOLTAGES WILL CAUSE DEATH,SEVERE PERSONAL INJURY OR PROPERTY DAM-AGE.All W-VAC and W-VACW breakers are equipped withseveral interlocks. These interlocks permit proper andsafe breaker operation.5-4.1 FLOOR TRIPPING, SPRING RELEASE ANDANTI-LATCH INTERLOCKSThese interlocks are operated by the inter- actionbetween the floor tripper rollers on the breaker bottomand the carriage or cradle assemblies. The functionsperformed are as follows:1. The breaker is held mechanically trip free duringracking. The latch check switch is also held open,thus preventing any electrical close signal from clos-ing the breaker.2. The breaker is permitted to be with drawn in thesafe mode (breaker open, springs discharged) whenbringing the breaker to the Withdrawn position or tothe Connected position.The outlined functions are accomplished by pushing upthe tripper rollers, which in turn rotates the Trip D Shaftor Spring Release Latch.5-4.2 LEVERING INTERLOCKThe purpose of this interlock is to prevent the leveringcrank from being engaged when the breaker is closed.An interference device on the cradle or carriage, whichis positioned by the breaker operating shaft, preventsthe levering crank from being inserted with the breakerin the Closed position.5-4.3 ANTI-CLOSE INTERLOCKThis interlock prevents releasing the closing springselectrically or manually, if the breaker is already closed.On a closed breaker the interlock lever moves towardthe rear. In this position the movement of the springrelease clapper does not lift the lever, thus the springrelease latch cannot be moved. This interlock applies tothe fixed W-VACR circuit breaker also.5-4.4 EARTHING DRIVE INTERLOCKThe earthing drive mechanism operates an interferencedevice to prevent insertion of the breaker when theearthing switch is closed.WARNING