Siemens SB Circuit Breakers
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The Siemens SB Circuit Breaker is considered a Molded Case Circuit Breaker by Siemens and NEMA. Siemens Website includes the following Information on Primary Amp Injection of these Breakers:
Q: How is the SB Systems Breaker tested using the primary current injection test?
A: All field-testing should be in accordance with NEMA standards Publication No. AB4. For more information on this publication and how to order, click on this link NEMA standards Publication No. AB4.
NEMA Standard AB-4 Applies so certain tests are considered to be destructive such as Instantaneous Overcurrent which exceeds 300% of the frame size of the circuit breaker. Siemens did not design a way to defeat the ground fault in the SB trip Unit, therefore when executing primary amp injection testing it is required to pass current through all three phases at the same time, otherwise the ground fault logic of the trip unit will always prevail. the Instantaneous unit is a separate processor so the defeat of the ground fault should not be necessary for this test as long as the test current remains less than 300% of the breaker frame rating. Use Table 2 in the NEMA AB-4 Standard to size the interconnecting conductors.