static micro-ohm resistance.pdf (35.2 KB)
I am writing to ask the community’s opinion regarding this manufacturer’s(Siemans+ “others”) publication regarding contact resistance, and milli-volt drop tests performed on power and molded case circuit breakers.
. We had a breaker that had a pole that was 3x phase to phase comparison as well as 3x like kind breakers in the same environment. I understand the I2R losses weren’t significant, but as a NETA contractor, I reached out to the manufacturer for any kind of compliance paperwork they would provide, and this PDF is what they sent me.
They specifically state that:
" The resistance value usually measured by many third-party testing
companies is irrelevant, and often misleading in new or nearly
new circuit breakers."
" The NETA document “Acceptance Testing Specifications” makes an
arbitrary statement as to the allowable tolerance of this
measurement when no tolerances are stated by the
manufacturer. As applied to Siemens circuit breakers, this
arbitrary pass/fail criterion has no basis in the practical
operational environment of the circuit breaker.For the reasons above, Siemens Industry neither publishes any tolerances for, nor recommends the testing of static micro-ohm or milli-volt drop across the main contacts of any
Siemens low voltage power or molded case circuit breakers."
" Siemens Industry does not accept the NETA "Acceptance
Testing Specifications" as an accurate means of validating the
quality or operational performance of its low voltage power or
molded case circuit breakers. Any test report or claim stating
that a Siemens circuit breaker is not suitable for its intended
application or service on the basis of contact resistance or
milli-volt drop, will not be considered acceptable evidence of
nonconformity for warranty action by Siemens."
