Final Thoughts

No More Excuses!

It is amazing how, when for some reason, we don’t want to do something, we always find some excuse. This fully applies to the use of non-conventional instrument transformers.

When I ask people why they are not switching to optical CTs, I hear many excuses, such as:

  • It is a new technology that is not mature enough
  • It is technology that can be used only in new installations
  • It is too expensive
  • It is not available at all voltage levels

Well, maybe these arguments were valid sometime at the end of the last century, but they are not true today.
Optical CTs have been available in different forms and shapes, with different interfaces for several decades now. It is true that the typical optical CT is easier to install in a new substation or when replacing the breakers or disconnecting switches in an existing installation.
However, the beauty of this technology is that it also offers much more flexible solutions that can be used for many different applications in substations, generating stations or wind turbines, mobile substations or any other case when there are challenging conditions that cannot be addressed with conventional current transformers.

The secret is an innovative flexible mounting type of an optical CT that allows an easy retrofit at any existing location, including difficult mounting locations. It is a fiber optic current sensor consisting of:

  • Flexible PVC conduit wrap-around sensing cable
  • Fiberglass sensor box
  • Electronics module

The sensing fiber resides in the PVC conduit, which attaches directly to the sensor box.  If we think about it, this addresses all concerns:

  • It is not based on a new operating principle and uses a communications interface based on IEC 61850 sampled values already used in numerous digital substations all over the world.
  • It can interface with IEDs from all major manufacturers
  • It is safer than any existing conventional current transformer and comes with all the benefits of an optical CT
  • It can be used at any voltage level, at old or new installations
  • It does not require any foundations and does not take any space in the substation yard or anywhere else

I can keep going, but there is simply no space. And what is clear, is that there are no more excuses to stay away from the optical CTs.