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Description: This non-invasive current sensor (also known as a “split core current transformer”) can be clamped around the supply line of an electrical load to tell you how much current is passing through it. It does this by acting as an inductor and responding to the magnetic field around a current-carrying conductor. By reading the amount of current being produced by the coil, you can calculate how much current is passing through the conductor.
This particular current sensor will measure a load up to 30 Amps which makes it great for building your own energy monitor to keep your power usage down, or even building an over-current protection device for an AC load. This sensor does not have a load resistor built in, so in most cases it will be necessary to place a resistor across the output to convert the coil’s induced current to a very small measurable voltage.
Based on 12 ratings:
3 of 3 found this helpful:
I wrapped 4 turns of my wire through the window of the CT for better accuracy, also found out the Tip and the Sleeve were connected to the CT, not sure what the ring is used for.
4 of 4 found this helpful:
Using an MCP3002/3004 analog to digital converter, I was able to get this sensor working with a Raspberry Pi. It was accurate to about a tenth of an amp when clipped around the hot wire of a short extension cord. Just what I needed!
1 of 1 found this helpful:
I was surprised at the level of detail I was able to get from this. I’m fascinated by the data I’m collecting. Plan to order quite a few more soon.
5 of 5 found this helpful:
Installed 2 of these to monitor current to heat pumps. Small size, split core design and long leads make installation easy in the elec panel but the thin plastic that acts as a hinge on the split core looks very weak. I used ‘zip’ ties to be sure they don’t open in the panel years from now.
I am using the cr magnetics design for a ‘precision rectifier’ to produce amplified DC voltage outputs with a ratio of 20mvdc/1Aac. Our typical 10Aac load produces 200mvdc output, easily monitored with an arduino.
The spec sheet uses a 10ohm load resistor to characterise the output voltage vs current curve. I’m using a 20ohm resistor to double the sensitivity. I ran a load curve and get linear results as with the 10ohm load but at double the sensitivity.
I currently work in engine research and have been frustrated for a long time that everyone seems to buy extremely expensive current probes and then leaves them on their test engines to measure the injector current trace. I figured that I would try this product and benchmark it against the expensive current probes. I adapted this sensor to plug into an o-scope and measured the voltage across a 10 ohm resistor that I placed in series in the current loop. This gave me a gain of 5mv/amp of current flowing in the circuit. To my surprise, this measured EXACTLY the same as the $600.00 current probe that consumes loads of 9V batteries! There was no detectable phase shift and the measured amplitude of the current was the same as well! I will be purchasing many more of these and outfitting our test cells with them to have dedicated injector measurement systems. Assuming that this product will stand the test of time (which it should since its a passive measurement probe) this has the potential to save us a lot of costs associated with these measurements!
I’ve been playing with it for a couple of weeks now. It really makes you understand things - if you like me would take this and try to measure something real, and I mean not just get some numbers, but really measure current, mains frequency, play with opamps and ADCs, learn to account for bias currents and offset voltages and so on and so on. And there’s a catch of course. I had an idea that you just clamp it around a cable and you all set - just ADC signal and that’s it. First, you don’t clamp this around CABLE, you clamp it around WIRE. An it’s just the beginning :-)
Works well with an automated current measurement system. One issue I’ve had though is that if you are measuring high currents (i.e. 25 amps) and the sensor becomes unplugged the voltage induced in the coil can arc over within the sensor and damage it. (Problem presents as a new, completely different current to voltage ratio.) I’ve lost three sensors this way. Not a big deal as long as you can avoid that, but annoying.
It works but calibrating is not an obvious exercise even with the printed material.
This is a decent current sensor. Alas, there isnt much documentation on it or how to use it. The device has a stereo 1/8" jack (3 connections) but the device only uses 2… Which two? your guess. The referenced “Arduino Energy Monitor Project” references the OpenEnergyMonitor.org … and their Emon library. Alas the project is for UK and tailored to their boards. The rather important Calibration step is obfuscated for other boards (bit of MagicHappensHere). Maybe when(if?) we finish ours we will correct that.
This sensor is great if you’re looking to check an ON or OFF state. However, if you’re looking to measure current, the output is not consistent for precise measurements. The clamp does not fit tight and that’s the problem. I have other clamps that are spring loaded and they stay closed tight.
Hmmm. These should be very accurate and the clamp should also stay latched with no issues. It sounds like you may have a defective part. I would suggest contacting our tech support team, they should be able to get this issue resolved for you.
This was the most economical solution to my oil burner monitor project. I bought these to log my oil burner motor and circulator on time (not power level) by sensing the current going to the motor. But it occurred to me that I would need to open some electrical boxes to place the current sensor around feed wires. I thought of an even more non-intrusive means when it occurred to me that the motor emits a magnetic field when it runs, so I simply placed the units (open) on the motor cases and they output a small ac signal when the motor was running. I fed this to my Particle Photon analog inputs and used a digital filter to detect when the motor was running. Very simple and easy, and the Photon fed the information directly to the internet, where I have a VPS server that logs the data.