Eaton ATC-900 Operation And Maintenance Manual

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IB140012EN For more information visit: www.eaton.comInstructional BookletEffective: March 2021 Page 15Operation and Maintenance Manual,Automatic Transfer Switch Controller, ATC-900Section 4: Operation4.1 GeneralThis section specifically describes the operation and functionaluse of the ATC-900. It is divided into three main categories:• Automatic Mode;• Test Mode; and• Programming Mode.The practical use and operation within each specific category willbe discussed in this section. It is assumed that prior sections werereviewed and that the operator has a basic understanding of thehardware. It is important that the operator have a good grasp ofthe functional use of the operator panel as covered in Section 3.This will make movement within each category and between cate-gories a simple task. This familiarity will quickly put the unsur-passed capabilities of ATC-900 at the operator’s fingertips.4.2 Automatic ModeThe Automatic Mode of ATC-900 provides for automatic transferand re-transfer from source to source as dictated by the featuressupplied and their programmed setpoint values. It provides a sum-mary of ATC-900’s intelligence and supervisory circuits whichconstantly monitor the condition of both Normal and Emergencypower sources thus providing the required intelligence for transferoperations. These circuits, for example, automatically initiate animmediate transfer of power when power fails or voltage levelsdrop outside a preset value. Exactly what the ATC-900 will initi-ate in response to a given system condition depends upon thecombination of standard and selected optional features.The usermay program several features and Input/Output functions.Optional features are: Closed Transition, Current Metering, andEthernet. Refer to Section 1.4.2When the preferred source is connected and the automatic trans-fer switch is operating normally, the status appears in the displaywindow. In the event of a power failure, the display automaticallybecomes active, showing the status of timers relative to an alter-nate source transfer. Once the alternate source becomes avail-able, the transfer is made consistent with pre-programmedfeatures. In a similar manner, transfer back to the preferred sourceis made once the preferred source is again available. System con-ditions relative to the sources and the load are clearly indicated bythe LED type mimic bus.4.2.1 I/O Functions & Contact RatingsAs described in Section 2, the rear access area provides foraccess to all input connections. The output relay contacts arerated for 10 A, 1/3 HP @ 250 Vac. The DC rating is 10 A @24Vdc. Each contact input (same for I/O Module) provides a wetted24 Vdc at 10 mA. Refer to Figure 2 for a graphical representationand position of all input connections. There are two types of I/Os,programmable and fixed. Most I/O are programmable by the userat any time. There are a few that are fixed from the factory.These I/O are fixed as the functions they performed are critical ordefined by factory installed hardware, and should not be repro-grammed by a user. For example, on switches equipped with ser-vice entrance, one of the programmable inputs would bepermanently set to "Go to Neutral".The ATC-900 provides for four in and four out programmableI/Os.Source 1 Auxiliary CloseThis input is located on pins 1 and 2 of connector J6 and factorywired to the Source 1 breaker (or contactor) auxiliary contact thatis closed when the Source 1 breaker is closed.S1 AvailableThis Form C relay is used to indicate the availability of Source 1.The full Form C contact of this relay is implemented with commonpin 1, normally closed (NC) pin 3, and normally open (NO) pin 2 ofconnector J4. This relay essentially duplicates the Source 1 avail-able status LED meaning that the setpoint criteria has been met.The relay contacts are rated for 10 A, 1/3 HP @ 250 Vac. The DCrating is 10 A @24 Vdc.S2 AvailableThis Form C relay is used to indicate the availability of Source 2.The full Form C contact of this relay is implemented with commonpin 4, normally closed pin 6, and normally open pin 5 of connectorJ4. This relay essentially duplicates the Source 2 available statusLED meaning that the setpoint criteria has been met. The relaycontacts are rated for 10 A, 1/3 HP @ 250 Vac. The DC rating is10 A @24 Vdc.Source 2 Auxiliary CloseThis input is located on pins 3 and 4 of connector J6 and wired tothe Source 2 breaker (or contactor) auxiliary contact that is closedwhen the Source 2 breaker is closed.S1 GeneratorThis latched coil relay provides a Form C contact on pins 1(COM),2 (NO), 3 (NC) of connector J15. The relay is the generator startrelay for system configurations employing a generator on theinput source designated Source 1. The generator start relay con-tacts are rated for 10 A, 1/3 HP @ 250 Vac. The DC rating is 10A @ 24 Vdc with a 150 W maximum load.S2 GeneratorThis latched coil relay provides a Form C contact on pins 4(COM), 5 (NO), 6 (NC) of connector J15. The relay is the genera-tor start relay for system configurations employing a generator onthe input source designated Source 2. The generator start relaycontacts are rated for 10 A, 1/3 HP @ 250 Vac. The DC rating is10 A @ 24 Vdc with a 150 W maximum load.NOTICEIT IS IMPORTANT TO REMEMBER THAT ATC-900 CONTINUES TOPROVIDE PROGRAMMED PROTECTION AND AUTOMATIC OPERA-TION NO MATTER WHICH MODE THE DEVICE IS IN AT THE TIME ITIS CALLED UPON TO OPERATE.NOTICETHE ATC-900 CONTROLLER MUST BE PROPERLY GROUNDED AT J-4, PIN 19 FOR PROPER OPERATION..NOTICECERTAIN INPUTS MAY NOT BE OPERATIONAL DEPENDING ON USERPURCHASED OPTIONS.