is it possible to use a rogowski coil with a magnetic core? ie i want to integrate the output of such coil rather to place a resistor on it. so, what is the differences between it and a current transformer?

application: to see only the waveform of a pwm current on an oscilloscope; max frequency= 200 kHz, duty cycle=[1 99] %, 20 A peak to peak

regards, ras

  • \$\begingroup\$ "to see only the waveform of a pwm current on an oscilloscope" you would use a regular Rogowski coil. Why would you want an iron core and how would you run the return conductor through the centre? \$\endgroup\$
    – Transistor
    Mar 8 '16 at 8:00
  • \$\begingroup\$ for its higher permeability. and why i should to return wire through the center? \$\endgroup\$
    – Rasool
    Mar 8 '16 at 8:20
  • \$\begingroup\$ Because that's how it works. \$\endgroup\$
    – Transistor
    Mar 8 '16 at 9:02
  • \$\begingroup\$ @Rasool - Your question re "why should I run the return wire throug the centre" suggests that you do not understand the ESSENTIAL construction requirements that MAKE it a Rogowski coil. Look at ALL correct (self fulfilling :-) ) descriptions of a RC and you will see that the return wire runs through the core centre. \$\endgroup\$
    – Russell McMahon
    Mar 8 '16 at 9:51
  • \$\begingroup\$ good answer Russell McMahon! in fact the essential advantage of the rogowski coil is its one-end construction. \$\endgroup\$
    – Rasool
    Mar 8 '16 at 10:26

An important stability consideration when probing currents is whether moving the sensed cable alters the reading. For instance, if you approach a current carrying wire with a Hall probe, the gain depends on the spacing.

A Rogowski coil solves this problem by using a symmetrical geometry (torus) in a uniform magnetic medium (air), and outputs a voltage.

A current transformer solves the problem by using a ring of very high permeability material, and outputs a current. Any geometry error is 'diluted' by a factor of the permeability.

You can have one or the other, they are mutually exclusive.

You can bring some of the Rogowski thinking to improve a current transformer by making the core and sense coils symmetrical, this will reduce geometry errors.

You cannot really bring any current transformer thinking to improve a Rogowski coil, you just end up with a half-designed current transformer.


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