Eaton Cutler-Hammer 36W-VAC25 Instructions For Installation, Operation And Maintenance

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

I.B. 3A74499BPage 16Effective 11/97SECTION 5: DESCRIPTION ANDOPERATIONCutler-Hammer Type W-VAC breakers are horizontaldrawout vacuum circuit breakers. They are designedspecifically to IEC 56 and KEMA certified to IECStandards, including their earthing system.Type W-VAC breakers are available in three mountingconfigurations. These include single tier designs anddouble tier designs for use in medal-clad switchgear,and a basic element design for use in retrofitting. Forthe single tier design, the basic breaker element ismounted on a carriage assembly. The basic breakerelement is mounted on a cradle assembly for the dou-ble-tier design. The carriage assembly and the cradleassembly both incorporate the racking mechanism andrequired safety interlocks.The basic breaker element, the breaker element with acarriage assembly, and the breaker element with a cra-dle assembly are designed to accept a variety of face-plates or covers. This permits the breakers to be veryflexible with respect to the type of structure used to formthe final switchgear assembly.Possibility 1 : The basic breaker element, by itself, isused for retrofitting purposes (Figures 3-3 and 3-4).Possibility 2: The basic breaker element combined witha carriage assembly is used for single tier switchgear.The breaker and carriage combination, however, can beutilized in a flush mounted configuration (Figure 5-1) ora behind the door configuration. The flush mounteddesign cover forms a deadfront design with the struc-ture, once the breaker is racked into the fully connectedposition.Possibility 3 :The basic breaker element combined witha cradle assembly is used for double tier switchgear.This combination is only for use in a behind the doorconfiguration (Figure 5-2).W-VAC breakers utilize Westinghouse vacuum inter-rupters to close and open the primary circuit. The mech-anism is a front mounted, spring stored energy type,which is common to all ratings. This one front mountedmechanism is easy to inspect, accessible for servicingand requires a minimum of spare parts. Because of theinherent long life characteristics of the vacuum inter-rupters and the highly reliable spring stored energymechanism, W-VAC circuit breakers provide long trou-ble free service with a minimum of maintenance.The primary insulation used throughout the W-VACdesign is flame retardant and track resistant glass poly-ester.5-1 INTERRUPTER ASSEMBLYVacuum interrupters are mounted vertically and support-ed from the fixed stem clamped to the top conductor(Figure 5-3). The current transfer system consists of aseries of tin-plated, high-conductivity copper leaf con-ductors that are pressed onto the movable interrupterstem.This provides a multipoint contact resulting in lowelectrical and thermal resistance. Since the currenttransfer from the movable stem to the breaker main con-ductor is a non-sliding design, no maintenance isrequired.5-1.1 VACUUM INTERRUPTERType W-VAC breakers utilize vacuum interrupters forinterruption and switching functions. Vacuum interrup-tion offers the advantages of enclosed interrupters,reduced size and weight, short interrupting time, longlife, reduced maintenance, and environmental compati-bility.Figure 5-1 Flush mounted configuration.