Over the years, Amran has produced custom Rogowski sensors/CTs
for various applications. Rogowski sensor is an air-core – usually toroidal or
rectangle coil placed around the conductor. Rogowski sensors do not use
magnetically permeable core. Since there is no magnetic core to saturate, one
of the most important properties of these coils is that they produce extremely
linear output. Rogowsi sensors are very popular for the application requiring
excellent linearity for very high current range.
Amran also manufactures combination of Rogowski CTs and CTs with
magnetic core. Both these are combined into one construction. These combination
CTs are typically used for protection application where magnetic core CT can
operate for low current range and then, once it saturates, Rogowski CT picks up
signal and provides appropriate output.
It is not easy to wind Rogowski sensors. Over the years, Amran
has developed equipment and expertise to wind these products uniformly so that
the coil does not pick up any magnetic signals from adjacent circuitry. Special
machines are used for accurate winding. Amran has state of the art in-house
test facilities to test Rogowski sensors for required parameters. Picture below
shows typical secondary output for Rogowski sensors.
Amran manufactures custom design coils for many OEMs. These
coils are usually wound on bobbin made out of engineering plastic material. The
coils can be precision wound on multi spindle machines with wire diameter from
0.05mm up to 3.5 mm for turns ranging from 50 to 50,000. Typical application
for such coils are LV and MV motor controls, relays, contactors, power control
equipment etc. Amran can integrate further assembly of these coils with other
components. Resin molding, vacuum varnishing, impregnation etc. procedures are
performed to ensure excellent environmental protections.