An ATS transfers power sources
An automatic transfer switch transfers loads between available sources. It is not a frequency converter, transformer or UPS, and cannot correct incompatible voltage, frequency or phases or increase generator capacity. Automatic engine starting does not establish that a complete ATS system is included in the quotation.
Typical automatic transfer sequence
A typical system monitors utility power, issues a start command under configured conditions, waits for acceptable generator power and transfers the load. After the utility returns and is stable, it retransfers and allows configured cool-down before stopping. Timing depends on equipment, settings and conditions. Common open-transition transfer interrupts supply; loads needing continuous power may require a separately assessed UPS solution.
An ampere rating alone is insufficient
Confirm voltage, frequency, phases, current rating, load type, short-circuit withstand/closing capability and protective-device coordination. Three-pole versus four-pole switching and neutral treatment depend on the earthing and neutral design. Closed transition involves brief source paralleling and relevant design and approval conditions; it is not a default ATS feature.
Define quotation and acceptance scope
Specify an integrated ATS or separate cabinet, control-signal compatibility, backed-up loads and acceptable interruption. Identify responsibility for site design, installation and commissioning. List whether the generator, ATS, breakers, cables and site work are included. Ask which configuration drawings and functional test records can be supplied; confirm the actual switch model and documentation for the order.
Technical reference: Cummins — transfer switch application manual