IEM3255 with summation current transformer possible?

[Sven_Ortmann]

Hello,

is it possible to use the IEM3255 with a summation current transformer?

thx

[JamesAZZO]

Summation CTs with 5A or 1A outputs work with any power meter supporting those inputs. The meter is blind to what is creating those currents.

[Sven_Ortmann]

At the customer the IEM3255 with Summation CTs shows only half of the real current.

What could be the reason?

[JamesAZZO]

The connections - particularly of the primaries into the summation CT may be suspect and you need to think about the proportions and size of the summing. 

As I mentioned before, if it's a true 5A or 1A output, the summation of the induced current must always be less than this. Please provide the make/model - datasheet on the summation CT you are using.

[Sven_Ortmann]

this is only half of current, and only half power.

its a KUW1/30-200 CT from Janitza

[Bojan]

Hi Sven,

This is actually Cable split core current transformer - they should probably have something like this, too:

Best regards,

Bojan

[Sven_Ortmann]

Hi Bojan,

yes they have a 1+1 but i think the summation does not work.

[Bojan · Accepted solution]

If they are connected, for example, like this, I would set CT Primary to 600A:

[JamesAZZO]

Exactly - Bojan's example is exactly right. It adds up the primaries, the proportions of which need to be added together.

That said - are you using a mix of 1A and 5A CTs going into the Summation CT?

[Sven_Ortmann]

Hi Bojan,

you are absolutely right. For 1+1 it sould be set to 400A. For 1+1+1 is should be set to 600A

Thank you very much

[Sven_Ortmann]

Hi,

no it is only 1+1 or 1+1+1