How do we select the proper voltage transformer for a given application?

In order to select the proper indoor type voltage t transformer for an application, there are four phases need to be addressed:

1- Define customer requirements based on the primary circuit and the metering and protection chains; i.e. define customer requirements in terms of voltage transformer specifications, key specifications can be summarized as follows:

• Rated primary voltage(s) or insulation level Ur/Ud/Ui in kV.
• Rated secondary voltage(s).
• Rated frequency (e.g. 50 or 60Hz).
• Earthing system (isolated or not).
• Desired accuracy class in measurement chain (e.g. class 1, 0.5 …etc).
• Desired rated burden (in VA) for measurement chain (e.g. 25VA).
• Desired accuracy class in protection chain (e.g. class 3P, 6P …etc).
• Desired rated burden (in VA) for protection chain (e.g. 25VA).
• Special requirements such as out-of-standard temperature/environment/altitude; connections; terminal covers; etc
• Installation type: either inside a SE cubicle (in this case the cubicle type and rated current need to be known) or in a non-SE cubicle.

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2- Select a “referenced” product from the CT/VT catalog (please refer to the latest catalog published). Note that our standard VT references are for only for non-isolated neutral systems unless indicated differently.

3- If no suitable VT has been found, you can still check the feasibility of the solution on “ELONET” using the “configured order” option for a given VT type or SE cubicle (note: in case a feasible solution has been found, the configured VT can then be ordered/procured via dedicated supply chain or intra-group purchase team).

4- If still no solution found, you need to fill-in a consultation form (per VT solution required) and send it back to technical support team for feasibility study; consultation form attached.

Released for:Schneider Electric Egypt and North East Africa