JAJSIU8B June 2015 – April 2020 ADS131E08S
Figure 60 shows the ADS131E08S being used as part of an electronic trip unit (ETU) in a circuit breaker or protection relay. Delta-sigma (ΔΣ), analog-to-digital converters (ADCs), such as the ADS131E08S, are ideal for this application because these devices provide a wide dynamic range. The fast power-up time of the ADS131E08S makes the device an ideal candidate for line-powered circuit breaker applications.
The system measures voltages and currents output from a breaker enclosure. In this example, the first three inputs measure line voltage and the remaining five inputs measure line current from the secondary winding of a current transformer (CT). A voltage divider steps down the voltage from the output of the breaker. Several resistors are used to break up power consumption and are used as a form of fault protection against any potential resistor short-circuit. After the voltage step down, RC filters are used for antialiasing and diodes protect the inputs from overrange.