PMAC Product Guide Opto-Isolation Circuits Delta Tau provides several opto-isolating boards allowing separate ground circuits. Opto-isolating accessories for encoder signals, serial communications and digital inputs and outputs are available. Example: Solution: In this case, a serial communications isolator board will keep the laptop and desktop grounds separated avoiding a ground loop. EMI, Electromagnetic Interference Electromagnetic interference (EMI) is an electrical noise which creates a disturbance or undesired response in one or more circuits, equipment, or systems. Usually EMI is due to magnetic fields originated by nearby high current cables or transformers.
Other sources of EMI include high voltage spikes generated by nearby solenoids, relays and arc welding machines. Twisted Wires In order to reduce electromagnetic interference, twisting of the power wires is highly recommended. Two wires carrying high current originates an inductive loop that is proportional to the area in between them: In a twisted cable, each adjacent pair of areas eliminates the inductive effect: 24 Wiring Guidelines