So far we have explained the benefits of the Rogowski Coil and when to select a Rogowski Coil over a current transducer, now we will explain to you the solution to the common problem of wrapping a Rogowski Coil that may be too large for the conductor.
Let’s first start with a refresher on the Rogowski Coil and its application:
A Rogowski Coil consists of a coil of wire precisely wound with a pair of terminals that connect to signal processing circuitry. The Rogowski doesn’t employ an iron core, which makes the assembly very flexible and can be easily installed around various types of conductor arrangements. Without the need for the iron core, a Rogowski Coil is capable of sensing very large currents and responding to higher frequency signals than a traditional iron core transformer.
Single Wrap vs. Multiple Wrapping
Let’s start off in the following scenario, saying you have a 12” Rogowski Coil, with 18 gauge conductors. You are in a situation where you bought a coil which is too large when wrapped once around the conductor. Don’t worry, you don't have to purchase a new coil. Now you may be wondering, “Do I wrap the Rogowski Coil once around the conductor (busbar/ legs) or can I wrap it around multiple times?”
Well, you can do both. Although the single wrap of the Rogowski Coil around the transformer is most common, you can wrap the Rogowski Coil as many times as needed around the conductor for a cleaner install. One thing to keep in mind when you wrap the Rogowski Coil multiple times around the conductor, the coil will pick up on extra current and transmit the extra reading to the power meter (Note: Multiple wrappings DOES NOT affect meter accuracy).
In simple terms, the output will be multiplied by the number of times the Rogowski Coil is wrapped around the conductor. So, as per our example, if you decided to wrap the 12” Rogowski Coil twice around the conductor, the Patrol Flex will sense twice the amount of output and send the double reading to the power meter. Unfortunately, there is no way to adjust for this in the meter output or the software, so manual calculations need to be done after the reading to account for the extra reading. In our example, if the Rogowski Coil is double wrapped around the conductor, divide the final output by two. If the Rogowski Coil is wrapped three times, divide the final output by three and so on.
CLICK HERE to learn more about Setra's Patrol Flex Rogowski Coil.