09-05-2012, 02:00 PM
Practical experiences and concerns
emi emc.pptx (Size: 178.73 KB / Downloads: 41)
Mains power supply :
1) Open wire electric power txn lines picks EM noises from lightning & Thunderstroms
2)Easily pick noise from Switches,CKT breakers,Heavy load switching.
3) Impair the operation of computer systems & information technology products.
4)care must be taken .
Switches and relays
Electrical discharge associated with the make /break contact operation of an electrical switch/relay
In telephone eqnt,control instrumentation can cause EMI
= ultra low level s/g handle -->>pb
EX: telephone,Radio telescope,High sensitivity control,telecommand ckts.
Telephone equipment
Telephone ckts in telephone central office picks noises from telivision stations so threshold level increases >1V/m (120dBUV/m)
So telephone line filters had to be designed.
Along woth radio s/g + EMI from digital clk pulses,power supplies (or) noise bursts from the operation of relays,
Switches and other electrical contact gaps
+Radio TV and other high power Tx’n.