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Techno Linear Motion Catalog 40 Technical Information Electronic Noise is a term used to describe unwanted disturbances as a result of electrical equipment. There are two sides to electric noise: the generation (or emission) of noise and the susceptibility of the equipment to noise. Susceptibility to noise can be dealt with at the design level by taking several precautions.  Encoders with TTL outputs should be avoided, and line driver encoders should be used.  Similarly, differential input should be used when possible rather than single-ended analog inputs.  Finally, digital I/O should be electrically isolated.  One further precaution is to use an isolation AC power transformer, even if not required. Electrical Noise Generation can be handled in a number of ways, and the following precautions should be observed to minimize the possibility of system disturbance: - avoid creating ground loops in an electronic design - keep the low level logic wires (encoder wires) separated from the power wires (motor   cables).  If they need to cross each other, do so at 90 degrees to minimize the effects   of magnetic fields - use twisted pairs whenever possible - use shields when possible and necessary, and connect one end of any shield to ground - put surge suppression components on all electric coils (RC filters, diodes, MOV’s) - filter the power line using common RC filters Having taken these precautions, electric noise should be kept below the system disturbance level. Grounding of machinery is often done incorrectly.  Some applications require that electrostatic discharge on system hardware be kept to a minimum.  The correct procedure is to connect a ground wire directly into the ground at the back panel of the controller used.  Any other grounding technique may produce a slight mismatch of ground potentials and subsequent noise problems. Motor Cable Gauge selection should be made in accordance with standardized wire gauge selection tables. The gauge is determined based on power requirements.  If a longer cable is preferred after selections have been made, it is recommended as a rule of thumb to move to a wire of heavier gauge, even if the desired length can handle the current.  Quick calculations can be made as follows: Increasing a wire by 3 gauge sizes doubles the amount of copper in the wire and reduces the resistance by half.  For example, going from 22 gauge to 19 gauge doubles the amount of copper and halves the resistance. Use  single  point  ground  for frequencies less than 1 MHz Use multipoint ground when frequencies are greater than 1 MHz.  Note that the ground leads must be kept short, or even  more  noise  could  be introduced into the system. The shield conductor should be  connected  to  the  signal reference ground.  It should be  connected  at  one  point only. Shield Load