Calculator
A Transformer Stability Test Calculator is a excel calculator tool for evaluating the performance stability of power transformers.
Such a calculator assists in estimating the transformer’s ability to function without tripping or sustaining damages under various electrical disturbances.
Procedure for Calculating Transformer Stability
Determine System Parameters
Compile all required transformer ratings, relay settings, impedance information, and CT data.
Determine Fault Currents
Determine the anticipated fault currents for various fault types based on the system characteristics.
For both balanced and unbalanced faults, this usually entails addressing the network using techniques like symmetrical components.
Analyze CT Performance
Determine how well the CT operates when there is a malfunction.
This involves determining how the relay readings will be impacted by the CTs saturating.
Relay Operation Analysis
Calculate the differential current and the difference between the primary and secondary CT currents and make sure it remains within the working parameters of the relay both in normal operation and in the case of external failures.
This is known as differential protection.
Verify that the relay will function properly in the event of internal errors.
Stabilizing Resistor Calculation
To prevent mal-operation owing to CT saturation or other transitory conditions, determine the required stabilizing resistor value for certain relays, particularly in high-impedance differential protection.
Transient Stability Analysis
To observe how the transformer and protection system react, simulate different fault conditions. Time-domain simulations may be used to watch how the relay behaves over time.
How to check the Stability of a Transformer?
- Measure CT terminal currents and maintain ratio for primary and secondary windings.
- Measure differential, resistance currents.
- Transformer differential circuit currents must be 1–3% of line currents.
- Enter the rated power, applied voltage both in high and low voltage side in their respective input values.
- The resultant tab provides the low and high voltage current of the transformer.
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