"Protection.

　　

　　Options for atS Protection

　　Within a spiecified acceptable damage criterion.

　　

　　Circuit Breaker Protection Options

　　ATSS Protected by Circuit Breakers Can Be Classified by One of Three WCRS:

　　3 by the corresponding number (1), (2), or (3).

　　(1) "Specific Breaker" WCR

　　The user of Specific Breakers for a PARTICular ATS Series. To view the list of special breakers test and accepted, contact the cereFacturer.

　　Certain issues may arise when specific breaker combinations are used. It is important to note that specific breaker ratings are usually a hindrance on bid day because, in most circumstances, the vendors providing the circuit breaker and the ATS are not the same. This places extra responsibility on the contractor and consulting engineer to make sure the ATS/circuit breaker pair is a tested, listed combination. Specific breaker combinations are often highly scrutinized by the authority having jurisdiction (AHJ) during an inspection. Although a specific breaker may be properly short -circuit combination rated with the ATS at the time of the initial installation, it is very likely that over the life of a system, the circuit breaker may need to be replaced. The person tasked with finding a replacement circuit breaker may not fully understand the importance of the relationship between the circuit breaker and the ATS it is protecting. If a new circuit breaker is installed that differs in type and/or rating, it may not be listed to protect the transfer switch and could be a potential hazard. Finally, if proper maintenance is not performed, the trip characteristics of circuit breakers may change as they age. The tripping time may become slower, thus exposing the ATS to energy above its tested and marked WCR rating.

　　(2) "Any Breaker" WCR

　　and not exceed certain damage criteria (See Figure 2, Option 2; And Figure 3, Column Marked (2)).

　　

　　* Per ul 1008, for 400 a or less, 10 ka any breaker WCR, the time withstand is only 1.5 cycles.

　　(3) Short Time WCr with Circuit Breakers

　　

　　Exceed The 3-Cycle Time Limit for the 3-Cycle "Any Breaker," Option 2 of Figure 2 and Column 2 of Figure 3 Cannot Be used.

　　The atS has been intented, the 0.1 Seconds (6 cycles), a 3-screen "Any Breaker" Rating Will Notquate Protection for the Ats.

　　Limited and Alsorsually Carry a Higher Price tag when it is compared to atssion with statedard WCRS.

　　Fuse Protection Option for ATS WCR

　　Addition to the Ease in Achieving ATS WCR of 200 Ka Because of their Current-Limiting Ability, Fuses Are Easy to Achieve Selective Coordination, Even Fault Currents.

　　

　　What determines an ats ’s WCR When Protected by Fuses

　　ATS’s WCR When Protected by a Circuit Breaker

　　When ProTected by Anstantaneous Circuit Breaker.

　　If using Fuse Protection, These ATS Characteristics Are A Non-ISSUE and the WCR IS Typically 200 KA.

　　To a design. With insunchient design scrutiny, theSe issues may exist during the initial construance or case during the fan, the system.

　　HOSPITAL ATS Example

　　Part Numbers have ben omitted.

　　Requirement:

　　, with a Nema 1 Enclosure.

　　Initial atS Cost Estimate

　　From atS Manufacturr:

　　The Estimated Cost Per Switch: $ 15,000

　　Cost for 5: $ 75,000

　　FOOTPRINT DIMENSIONS PER SWITCH: 34 In. X 28 In.

　　ATS Cost Modify Due to Fault Current

　　.

　　Then, then

　　From atS Manufacturr:

　　The New Cost Per Switch: $ 35,000

　　Cost for 5: $ 175,000

　　FOOTPRINT DIMENSIONS PER SWITCH: 38 in. X 60 in.

　　AdDitional Cost

　　$ 20,000 Per ATS X 5 = $ 100,000 to Owner

　　Additional Electrical Room Floor Space Required = 20 In. X 160 In.

　　

　　

　　Right-size to avoid Change Orders

　　The follow is another real atXample. This Illustrates is that may arise after initial design.

　　

　　, There will be sectre change order core involved.

　　Change is made.