Coils for Instrument Transformers – Which Parameters Are Key When Ordering?

Coils for medium voltage current and voltage transformers are components that determine measurement accuracy and the safety of the entire electrical installation. Therefore, it is crucial to define parameters correctly when placing an order.

1. Rated current and accuracy class

You should specify the required primary and secondary current and the accuracy class of the transformer (e.g., 0.2, 0.5, 1). Incorrect matching may result in inaccurate measurements.

2. Number of turns and winding type

The manufacturer must know the exact number of turns and the winding configuration – whether it is single or multi-turn, toroidal or layered.

3. Wire type and cross-section

It is important to specify whether copper or aluminum wire will be used, along with its cross-section and insulation type (e.g., double enamel, medium voltage rating).

4. Operating conditions

Temperature, humidity, and industrial environment – this data helps to select appropriate materials and protective measures for the windings.

5. Testing and certification

Voltage or impedance testing or compliance with standards (e.g., PN-EN, IEC) may be required. It’s worth checking whether the manufacturer provides full documentation and test reports.

Accurate parameter definition at the inquiry stage helps avoid errors, delays, and additional production costs.