How do you calculate the voltage of a transformer?
For example, a voltage source that sends 240 volts through a transformer with 500 primary windings and 100 secondary windings would have an output voltage of 240 * (100/500) = 48 volts.
What is per unit impedance of transformer?
The per-unit impedance describes that percentage of the rated voltage required to produce full load current while the transformer output is shorted. The lower the impedance, the lower the voltage required to produce full load current. A voltage is applied to the primary with the secondary winding shorted (faulted).
What happens if a transformer has a 6.33% impedance?
If a transformer has a 6.33% impedance, it would require 6.33% of the input primary voltage to cause 100% of the rated current on the secondary windings when a worst case fault occurs. In electrical distribution systems, the worst case fault is when a low impedance metal bar shorts the lines and is called a bolted fault.
How does the per unit impedance calculation work?
The per unit system of calculation is a method whereby system impedances and quantities are normalized across different voltage levels to a common base. By removing the impact of varying voltages, the necessary calculations are simplified. To use the per unit method, we normalize all the system impedances (and admittances)…
When do you step up the voltage on a transformer?
Very carefully, the voltage on the primary lines is stepped up until the secondary full load current is reached. For example, this 2500 kVA, 12.47 kV to 600/347 V transformer shown in the photo:
What is the current rating of a 2500 KVA transformer?
For example, this 2500 kVA, 12.47 kV to 600/347 V transformer shown in the photo: Once the secondary current reaches 2406A, a voltage reading is taken on the primary to see what input voltage is required to reach this full load current rating on the secondary.