What are the common methods of current sensing?
CT current sensing is inexpensive. The CT method is used primarily with commercial power frequencies of 50/60 Hz. The CT method is used in instruments such as clamp power meters used in managing energy savings in buildings, among other applications.
How does current sensing work?
Current sensors are either open- or closed-loop. Open-loop current sensors measure AC and DC currents and provide electrical isolation between the circuit being measured and the output of the sensor (the primary current is measured without electrical contact with the primary circuit, providing galvanic isolation).
Why is current sensing important?
Current sensor based on Faraday’s Law These sensors provide an intrinsic electrical isolation between the current to be measured and the output signal, thus making these current sensing devices mandatory, where safety standards demand electrical isolation.
How use ACS712 current sensor?
About Acs712 Pin out and Pin description of the chip is below. Connect the sensor in series to the system whose current you want to measure. Cut the circuit wire and connect one end of wire to IP+ and other to IP-. Recall the high school lectures, current can be measured only in series.
What’s the difference between high side and low side current sensing?
In the low-side configuration, the current sense resistor (Rshunt) is placed between the ground terminal of the power supply and the ground terminal of the load. With the high-side method, the shunt resistor is placed between the positive terminal of the power supply and the supply input of the load.
What’s the difference between high-side and low-side current sensing?
What is high-side and low-side current sensing?
High-side versus low-side current sensing When monitoring load current the designer can choose to place the sense resistor either between the supply voltage (Vbus) and load, or between the load and ground. The former is called high-side sensing whereas the latter is called low-side sensing.
What is sensitivity of current sensor?
Current sensors provide sensitivity down to 26.7mV/A.
What is differential current protection and how does it work?
Differential current protection is most practical to implement over short physical distances, such as over the phase windings in a generator or some other power system component, but the fundamental concept is applicable over longer distances as well because Kirchhoff’s Current Law knows no bounds.
What is a differential current relay?
In other words, this is a type of system fault that would not necessarily be detected by an overcurrent (50/51) relay, and so must be detected by some other means. The relay type designated for this task is called a differential current relay. The ANSI/IEEE number code for differential protection is 87.
How is the differential signal amplified in a circuit?
The differential signal is amplified through a sense current across a low-side shunt resistor. This topology takes advantage of the fact that actual currents flowing does not travel at the speed of light.
Can a transformer fault go undetected by a differential relay?
However, one common transformer fault which would go undetected is a turn-to-turn fault within one of the windings. Such a fault would skew the turns ratio of the power transformer, but it would not upset the balance of current going in and coming out of any given winding and therefore would go undetected by the differential relays as shown.