(xl) Calculate Transformer Size – Voltage Drop due

Transformer Size ~ Voltage Drop due to Starting of Large Size of Motors

This document provides an example calculation for sizing a transformer and checking the voltage drop due to starting a large motor. It calculates the voltage drop from starting a 300kW motor powered by a 1000kVA, 11/0.48kV transformer with 5.75% impedance. The calculations show that the voltage drop of 10% is within the allowable limit. Therefore, the existing transformer size is adequate to handle starting the motor without excessive voltage drop.

Reference Wikipedia – https://en.wikipedia.org/wiki/Transformer

1. Calculate Lock Rotor Current.
2. Calculate Motor Starting Current.
3. Calculate Motor Full Load Current.
4. Calculate Non-time Delay/Time Delay fuse Size.
5. Calculate Circuit Breaker Size.
6. Calculate Overload Relay setting.
7. Calculate Type of Contractor.
8. Calculate Size of Main Contractor.
9. Calculate Size of Star Contractor.
10. Calculate Size of Delta Contractor.
11. Standard Arrangement of Main and Auxiliary Contractor

Title : Transformer Size ~ Voltage Drop due to Starting of Large Size of Motors

Type : Microsoft Excel Spreadsheet (xlsx)

Size : 37 KB