Frequently in industrial applications, a high voltage and/or high current system must be monitored to ensure that the electrical power properties of the system meet select criteria, such as remaining within a voltage range, and/or remaining within a current range. Such systems frequently have power variations and fluctuations, such as transients, which can potentially damage sensitive equipment and controllers.
One solution to problems caused by transients, which is recognized in industry, is gap isolation of the controller via optocouplers, inductance couplers, capacitor couplers, or other gap isolation circuits.
By way of example, an optocoupler is an electronic device that transfers an electrical signal across an isolation gap by converting the electrical signal to optical light, and back to an electrical signal after passing through an insulation medium. The main objective of optocouplers is to provide high voltage isolation protection on the outside of the circuit, when there is a surge or spike in the voltage rating on the input side.
A typical optocoupler needs a light source, such as a Light Emitting Device (LED), a photodetector, and an insulation medium. The insulation medium of the optocoupler can be either transparent polyimide or epoxy molding compound that allow optical light to pass through.
One limitation of existing optocouplers is that they cannot take in the high current directly. Rather, the incoming current is often passed through external resistors to limit the current, thereby increasing the costs associated with implementing the optocoupler.
Other gap isolators operate similarly with a different type of signal being transmitted across the gap. For instance, an inductance coupler will convert the signal to inductance and then back into an analog electrical signal instead of using an optical signal. While such an arrangement addresses the potential problems caused by a high voltage load in direct connection with a controller, it can give rise to other problems such as scaling factors and the like.