Let’s face it, choosing a current sensor can be confusing, and it doesn’t help when there are literally hundreds to choose from! So how do you sort through all these variations to find the perfect current sensor for your application? Luckily, knowing just 4 key things about your application can reduce the number of current sensors to choose from. Down from hundreds to a small handful.
Current Sensing Type & Range
In every current sensor application, there is obviously a current that is being sensed. Knowing what that current is doing or could do is essential to choosing a current sensor. Many current sensors have restrictions on what type of current they can sense, or even operate with. Most only work with AC current at 60Hz. Others can work over a range of frequencies. Still others only work with DC current. It’s important to make sure the current sensor you choose can sense the current type you have. Each current sensor also has a current range it can operate with in Amps. The minimum and maximum possible currents going through your sensed wire should always be within that range as anything outside could either be missed or damage the sensor.
Sensor Output Type and Ratings
Once a current sensor has sensed current, it needs a way to communicate that to the rest of the application. This could be to a controller, logic board, relay, switch, or something else entirely. Several common ways to do this are through contacts and transducers. Contacts usually have a rating associated with them, and it’s important to make sure your application fits within those so as not to break the current sensor. If you’re triggering a large load with a current sensor, it might be worthwhile to get a dry contact input relay or relay and current sensor combo. Transducers usually come in three flavors, 4-20mA, 0-5V, or 0-10V. Controllers often only work with one type or another so be sure to match your sensor to it.
If you choose to go with the contact option for the current sensor output, then you’ll need to decide the sensing threshold as well. This is the point at which the sensor activates and closes or opens its contacts. There are two types of thresholds, fixed, and adjustable. Fixed being a factory set threshold, and adjustable being one you can set yourself. Knowing what you want your threshold to be, and if it can change will help you decide between the two.
Finally, the actual physical size of the current sensor is something to look out for. There have been multiple times I’ve heard of people going over the above specifications and choosing what they think is the perfect current sensor. Only to find out that the aperture isn’t big enough for their wire, or the terminals are too small, or the current sensor itself doesn’t physically fit in their application. Check and double check your wire diameter (including insulation) and the size space you want to install in before settling on a specific current sensor.
That’s everything! Provided you have those four things figured out, you can easily pick a current sensor that will work for your application. Any other choices you have will come down more to convenience or personal preference (such as split vs. solid core) rather than any actual compatibility with your application. Be sure to use the website filters to help you choose, and if you still can’t decide on a current sensor, feel free to contact us at Tech Support!