This can best be described using the Current Transformer's Ratio Correction Factor or 'RCF'.  The 'RCF' can be multiplied by the primary of the current transformer to obtain the amount of ampere error in the billing calculation.  A value greater than 1.0000 means that you are supplying more amperes than you are measuring.  Conversely, a value less than 1.0000 means that you are supplying less amperes than you are measuring.  An example would be as follows:

Suppose you are using a 200:5 current transformer with 300 amperes on the primary, the output to the secondary would be 7.5 amperes. If the current transformer had an 'RCF' of .9980, the true primary amperes to get a 7.5 ampere secondary would be 299.4.

It is important to understand that the lower the primary load, in terms of it's load percentage on the current transformer, the higher the 'RCF' will be and also the higher the Burden, the higher the 'RCF' will be.  Since current transformers are compared for accuracy with primary loads of 10% and 100%,  and burdens of .1 and at the maximum rated, the most extreme readings of a current transformer will occur as follow:

• The highest 'RCF' will occur at 10% primary load at the maximum rated burden.
• The lowest 'RCF' will occur at 100% primary load at a burden of .01.