When it comes to current sensors, you have two main options: open look or closed loop. Open loop current sensors can measure either AC or DC current and offer you electrical isolation between the circuit you are trying to measure and the output of the sensor in order to provide you with a more accurate measurement. In addition, they tend to be less expensive than their closed loop counterparts. Electricians and engineers prefer to use open loop current sensors in a battery powered circuit because they have a low power requirement to operate.
Closed-loop current sensors, on the other hand, can also measure AC and DC currents as well as provide electrical isolation. In addition, they offer a quick response time, high linearity and a low temp drift. Additionally, the current output is insulated from electrical noise.
So, how do you know whether you need an open loop current sensor or a closed loop current sensor for your unique application? It’s important to distinguish the difference between the two different types of sensors.
Closed loop current sensors are well known in the industry for providing highly accurate readings thanks to the inclusion of a Hall generator located in the air gap of the core. The key features of a closed loop current sensor includes:
- Unipolar voltage supply
- Isolated plastic case recognized according to UL 94-V0
- Compact design for PCB mounting
- Incorporated measuring resistance
- Extended measuring range
Closed loop current sensors are often used in industrial applications where they can be used to measure the current in AC variable speed drives, servo motor drives, uninterruptable power supplies, switched mode power supplies, and power supplies for most welding devices. Of course, these aren’t the only places where you can use a closed loop current sensor.
Both open and closed loop current sensors are both economical solutions when used in the appropriate applications, open loop sensors will generally have the lowest price tag at the point of sale and will provide the most economical solution in high current applications where currents are expected to exceed 100 amps. They are also smaller in size and ensure a steady constant power consumption, no matter the size of the current being measured.
However, if you are working within a commercial or industrial environment, you may find that while closed-loop current sensors will cost you a few more dollars to acquire, they will provide a greater deal of accuracy, especially in higher temperature conditions than open loop sensors. they also provide a faster, more accurate measurement in noisy environments. Last but not least, the output created by a closed loop sensor can be easily converted to voltage from amperage.