EMC / EMI / ESD
Rapid Transit Industry
Rapid transit railcars,
including subway and commuter trains, generate electromagnetic disturbances
that can affect the operation of the train-borne equipment as .well as
wayside equipment. Under federal regulations, transit authorities need to
ensure the railcar design meets emission and immunity limits for
Each equipment on the
train should be designed to suppress the emission of electromagnetic
disturbances and also be immune to EMI in its operation environment. To
ensure EMC, equipment are subject to a set of EMC tests.
equipment assembled on the train, a different set of train-level tests are
to be performed to ensure EMC for operation and safety.
discharges that we all experience, especially during winter time, are
harmful to tiny transistors inside integrated circuits (IC). When ICs are
"zapped" during manufacturing of circuit boards, they may not be totally
damaged, but rather are knocked out of specification slightly and pass
production test as "good boards". These boards, with latent damage, are
continued used in higher and higher integration and could be the cause of
pre-mature failure in field use.
IC designers are
required to include ESD protection circuits in their design, and product
qualification tests should include testing against two types of ESD -- Human
Body Model and Charged Device Model to ensure high degree of immunity to ESD
Effective control of
ESD generation in manufacturing environment is critical to produce high
quality electronic products. Weeding out latent damaged IC boards prevents
pre-mature field failure and increases customer satisfaction.