# Transformer set-up in Device management

Hi Experts,

I'm trying to analyze set-up of transformer in IS-U DM. I have following questions:

1) To calculate Billing Factor CT/PT ratio and Transformation ratio are used. What is the significance of both these ratios? How they are practically available in transmission of electricity?If transformation ratio is there, will it not suffice the calculation of billing ratio alone?

2) Is only technical installation of transformer sufficient for calculating billing ratio?

3) What will happen if there are 2 CT & 2 PT transformers available. How the billing ratio is calculated?

##### Former Member replied

Hi Vinod,

In transmission division, electricity is transported at high voltage and it cannot be measured directly by meters. CT/PT are devices used to scale large primary currents/voltages - to a smaller, easy to measure, secondary

currents / voltages.

Once current and voltage are brought down to smaller values, it is measured by meters. Since, we are measure secondary part, we need to apply transformation ration in order to calculate actual primary values.

Hope you are able to follow. Please let me know if you need any details.

Regards,

Avinash