All About AC Current and Current Sensing
Ezurio BT610 I/O Platform supports any sensor that can be connected via standard digital or analog, SPI, I2C, and UART. Ezurio provides sensor accessories as well, including multiple AC current sensors. Here, Ezurio addresses the most popular questions about AC current.
Frequently Asked Questions about AC Current
Ezurio BT610 packaged units address a wide variety of sensor applications, but a very popular one is AC current sensing. With Ezurio Canvas firmware, it’s extremely simple to upload their sample application, connect a sensor, attach it to a power supply line and start measuring real time AC current consumption.
In this post, we’re looking at some of the internet’s most commonly asked questions about AC current: what it is, how it works, how to measure it, and much more. We start with the absolute basics and proceed to more specific questions and look at several use cases, and how Ezurio AC current sensor can help.
FAQs:
What is AC Current? How does AC Current flow?
AC Current stands for Alternating Current (making the “Current” in AC Current a bit redundant). It describes an electrical current which switches polarity in rapid succession, moving forward and backward through a circuit in rapid succession on a fixed phase. Both the voltage and the current oscillate in this way, sawing back and forth throughout the power line. The frequency, or rate at which this oscillation occurs, is measure in hertz (Hz), and this rate varies around the world. AC current is how power is delivered to homes and businesses by power utilities.
Current is measured in Amps. In Ezurio AC Current sensors, that value is expressed as Amps in the Root Mean Square value (A RMS), which is an average value of amps. Ezurio sensors are capable of measuring in the, the 0-150A RMS range, and 0-500A RMS range.
Who invented AC Current?
As with many questions of invention, it’s hard to pin down AC current to a particular individual. Discovery always builds on discovery, and all inventions stand on the shoulders of the research and experimentation before them. Today, Nikola Tesla is often considered the father of AC current, and also invented the 3 phase AC system and motors which translated AC current into motion.
However, many inventions and discoveries preceded this. Michael Faraday is credited with the 1831 discovery of electromagnetic induction which made this all possible. Hippolyte Pixii built an early AC current generator based on Faraday’s discovery, a proof of concept that moved the technology forward. George Westinghouse bought the patents for Tesla’s inventions and built the first power plants to make its generation and distribution possible.
The proliferation and application of alternating current relies on the work of countless scientists and inventors whose work powers our modern world.
What is meant by 60Hz AC Current?
As mentioned, the frequency of AC current varies around the world. Hertz is a measurement of the complete period of oscillating frequency per second. Applying this, 60Hz means the cycle repeats 60 times per second.
60Hz AC Current is the standard in the United States and many other countries. However, in many parts of the world, 50Hz AC Current is the standard.
It is worth noting that the frequency is not what is measured by AC Current sensors. Current is a separate measurement from oscillation frequency.
What’s the difference between AC Current and DC Current?
The alternative to AC current is DC current. DC stands for Direct Current. In this form, current does not alternate back and forth through the circuit, but instead flows directly from the positive end of the circuit (the anode) to the negative end of the circuit (the cathode). This is the form of current that battery-powered circuits use, where the anode is represented by the (+) symbol, and the cathode is represented by the (-) symbol.
Is household current AC or DC?
Household current is alternating current, and for good reason. AC Current is much easier to transmit over long distances, making it ideal for use in power lines to distribute to customers with less degradation. However, it is worth noting that AC current may be more dangerous to the human body, so it’s important to use precautions when working with electrical equipment and ideally to only have electrical work performed by a licensed electrician.
How does AC Current work? What uses AC current?
At first glance, it may be difficult to imagine how current which moves back and forth, but ultimately does not flow continuously through a circuit, is able to provide power to devices. In some cases, AC current’s application is very simple. In others, intermediary hardware is needed to make it useful to devices.
For example: In a lightbulb, the rapid back-and-forth of AC current is, by itself, stimulating enough to the filament of a lightbulb to generate heat and light via the resistance of the filament. The filament is designed with resist that current flow and the natural result of this is, as explained, heat and light. Nothing is needed in between the AC current and the bulb to generate this effect.
Many simple devices which rely on resistance like this are able to utilize AC current directly to function.
What about DC current? How does AC current become DC current?
In more complex or sophisticated electronics, it may be necessary to convert AC current into DC current. For example, it’s hard to imagine power accumulating in a battery without some mechanism to convert that back and forth motion into a directional and accumulating current. This is what a DC current converter does. Alternating current is passed through a circuit which converts that energy to a forward-only current using rectifiers, capacitors, and regulators, which prevents the reverse flow of current and makes sure the forward-moving current is of a predictable frequency and the appropriate current.
A DC converter is most commonly seen as the power brick on your laptop plug, or other hardware inline on the plug that goes between your wall outlet and your device.
Different devices have different power requirements, and the less resistance in a circuit, generally, the greater the current flow. Measuring this current consumption with an AC Current sensor can be useful for more than just understanding how much power is being drawn. It can also be an indication that something is wrong with a device, and therefore indicate issues, such as a need for maintenance.
How do you measure AC Current?
There are multiple ways to measure AC current. Different methods may require a direct line into the circuit, while others (like our AC Current sensor) are exterior and minimally invasive. The following are a few methods.
- How to measure AC current with a multimeter: A multimeter connects two wires in series with the circuit, and determines the current via direct interaction with the circuit.
- How to measure AC current with a current shunt: A shunt resistor can be inserted in circuit, and by paying attention to the voltage drop across the shunt, you can determine the AC current of the circuit.
- How to measure AC current with a clamp meter: This is the method used by our AC current sensors. In this method, a clamp is placed around the wire, requiring no invasive and direct connection to the circuit. A clamp meter uses magnetic induction to determine the AC current of the line.
Ezurio BT610 AC Current Sensors: Simple, Non-Invasive, Reliable Current Measurement.
As previously mentioned, Ezurio BT610 is able to connect to many, many off-the-shelf sensors which are designed to interface with standard analog, digital, SPI, I2C, and UART connection. It’s an open development device that enables you to input multiple sensor types and relay them over Bluetooth for a cable replacement solution that’s easy to use and widely extensible.
In combination with Ezurio Canvas software suite, it’s also very easy to program. Ezurio reference files, sample applications, and more are built around MicroPython, a simple and familiar development language that provides a quick way to define inputs and outputs and drive applications for these commonly available sensors.
Ezurio AC Current sensors are just one of these options, and are available for current requirements all the way up to 500 A RMS, with a clamp-on form factor that can be installed around existing wiring without having to connect inline to a circuit or interfering with existing wiring. And because the BT610 is battery-driven, you can install anywhere without a need to worry about wiring into AC power.
For more on Ezurio BT610 sensors, please visit the Ezurio website:
https://www.ezurio.com/iot-devices/bluetooth-iot-devices/sentrius-bt610-io-sensor
To see how far battery-power can take your application, try Ezurio handy battery life estimator calculator, which takes into account your refresh rate, number of inputs and outputs, and specific sensor types in order to calculate your battery life in years:
https://www.ezurio.com/technology/bt610-battery-estimation-calculator
Courtesy of Ezurio
