Rogowski – Coils
As well as conventional current transformers, also Rogowski coils can be used for measuring current. The absence of an iron core means that no non-linear effects arise. Rogowski coils are easy to attach and remove without disconnecting the power circuit, i.e. without significant assembly work. These sensors are extremely easy to install. Just a few simple steps are required to position the coil around the primary conductor and to connect it to the closure. The primary conductor does not need to be disconnected. The Rogowski coils FASK in combination with the universal converter QE-485 provides a freely configurable analogue output, a digital output and an RS485 Modbus RTU interface.
FASK
Benefits oft the Rogowski coils FASK
The Rogowski coils FASK 100, 150, 200 and 300 are completely shielded, and are therefore extensively protected from interference effects.
All Rogowski coils generate a relatively large output signal of 100 mV/kA. Because of the coil’s good linearity, even relatively small primary currents well below 1 kA can be measured accurately. The Rogowski FASK coils have a phase error between -0.4 and -0.5 °, and so a fixed correction factor can be used in the measurement device. The materials permit use in very aggressive ambient temperatures. The coils generate no waste heat. The supply cable can be shortened without loss of accuracy.
The ROI-3 integrator
In order to correct the phasing of the passive Rogowski coil by 90°, an integrator circuit is necessary. At the same time it is desirable to maintain a standard signal, in order to ensure compatibility with the usual measurement devices. The three-phase ROI-3 integrator is ideally suited to an output of 1 A. Three Rogowski coils can be connected simultaneously. A 24 V DC source is required as the voltage supply. Installation on a 35 mm-DIN-rail is intended.
Benefits of the ROI-3
Compact casing for the connection of three FASK. The ROI-3 does not measure direct currents when used with the FASK; however, in contrast to a conventional current transformer it can perform exact measurements of the alternating current component, even if a large superimposed direct current component is present, because there is no iron core to cause saturation. This function is particularly important for the measurement of ripple currents, e.g. in battery charging systems. The ROI-3 integrator has relatively good frequency behaviour.
QE-485 – Universal converter with analogue and Modbus output
The QE-485 universal current and voltage converter is the all-in-one solution for all your measurements, monitoring and analyses. It enables the connection of Rogowski coils, current transformers, measuring transducers and all-current sensors (Hall sensors). There is also the option to monitor temperature at the same time. On the output side, the converter provides a freely configurable analogue output, a digital output and an RS485 Modbus RTU interface.
