Eaton Ampgard 400 Instruction Manual

3Instructional Leaflet IB48041Effective December 2009Instructions for AMPGARD 400Amedium voltage startereaton corporatIon www.eaton.comDescriptionControllerThe AMPGARD 400A, 7.2 kV controller consists of a non-loadbreakisolation switch, medium voltage current-limiting fuses, one ormore Type SL vacuum-break contactors, a set of current transform-ers, plus control and protection devices. The isolating switch has alimited make and break rating, suitable only for closing and openinglimited transformer magnetizing currents. The controller is designedto start, stop, and protect a three-phase medium voltage motorwithin the ratings shown in Table 1. The controller may also be usedto switch transformer windings or capacitor loads as shown. Forapplications other than those indicated, consult the factory. EachAMPGARD controller occupies all or a portion of a steel structurethat may also enclose a horizontal bus system to distribute power totwo or more sections and a vertical bus system to connect individualstarters to the horizontal bus. The controllers are configured for full-voltage or reduced-voltage starting, reversing or non-reversing, insingle-speed or two-speed applications.Starters are available with bolt-in or clip-in main fuses. Contactorsmay have bolted connections or stab-in connections to thestarter cell.The flow of current through a starter with bolted fuses and astab-in contactor can be described as follows: The line fingerassembly mounted at the back of the enclosure serves to connectthe isolation switch moving stabs to the controller line terminalswhen the switch is closed. Power flows from the switch movingstabs through a flexible shunt to the upper fuse mountings. Thefuses are connected to the lower fuse mountings that contain theline-side stab connections to the line finger assemblies for the maincontactor. With the main contactor energized, power flows throughthe contactor’s vacuum interrupters to the contactor load fingers,which are engaged on to the contactor load-side stabs. Mediumvoltage cables connect the load-side stabs to the motor loadconnections. The contactor is held in place by a set of railsmounted in the lower part of the cell. Current transformers aretypically mounted immediately behind the main contactor, under theload-side stabs. The motor load connections are mounted to the leftof the main fuses in the rear of the compartment, facing forward.Figure 2. Medium Voltage CompartmentLow voltage componentsThe low voltage components consisting of a protective relay,interposing relay, test power circuit, terminal blocks, and optionalequipment are mounted in the low voltage control compartmentlocated on the front of the controller medium voltage door. The lowvoltage compartment is fabricated from steel sheets to provide iso-lation from the medium voltage components mounted behind thelow voltage compartment. A window is provided in the low voltagecompartment to allow the user to view the position of the isolationswitch before entering the medium voltage compartment. See the“Isolation Switch” section for further details.Figure 3. Low Voltage CompartmentIsolation switchThe controller isolation switch is a non-loadbreak device.Mechanical and electrical interlocks are provided to ensure thatthe main contactor is de-energized before the switch can beoperated. In the open position, the switch isolates medium voltagefrom the main controller compartment, allowing access to thecontroller for inspection and maintenance. For standard applications,the isolation switch includes ground fingers that ground the line sideof the power fuses when the switch is in the open position. Theisolation switch has a mechanical endurance rating of 10,000operations. Isolation switches in starters with double-barrel fusesare supplied with additional phase barriers that must be installed tomaintain the proper dielectric rating of the starter. DangerampgarD controllers are sometimes energizeD by a back-feDconDition that allows the meDium voltage compartment to beenergizeD with the isolation switch in the open position. stuDythe plant single line Diagrams to make certain that no back-feeD situation exists before entering the meDium voltagecompartment.All power sources must be isolated and locked out beforeservicing the equipment.For applications where the controller is back fed, the groundingfingers should be removed from the isolation switch.The switch consists of a fixed rear portion and a removable frontportion. Refer to Figures 5 and 6. The fixed portion includes thecontroller line fingers and a moveable shutter that isolates the linefingers when the switch is in the open position. The removableportion is operated by a handle mechanism that extends through thecontroller medium voltage door. With the handle in the up position,the switch is closed and medium voltage is available for connectionto the controller load. With the handle in the down position, theswitch is open and medium voltage is isolated from the controllerand the controller load.An isolation switch viewing window is provided in the upper rearcorner of the low voltage control compartment. After opening theisolation switch and before opening the medium voltage door, theswitch should be visually examined through the viewing window toverify that it is in the open position. Three green and white “barberpoles” will be visible when the switch is in the open position andthe shutter assembly is in the isolating position. See Figure 4 forlocation of barber poles. The use of a flashlight will help in verifyingthe position of the barber poles.Isolation SwitchPosition ViewWindow