I have a 34kv/380/500KVA transformer and it loads a pump of 450HP/2200V. Starting current reaches up to 1700 amps for around 3-4 seconds using a soft starter. The rated capacity of the transformer is 700amps and the pump running current is 689 amps.Any calculations to prove that the transformer is enough to provide the application would be a help.thanks.
Damn, had to read the question before I realized it has NOTHING to do with Optimus Prime or Megatron. (*laughing*)
500 kVA ÷ 0.380 kV ÷ √3 760 amps The nameplate rating (kVA) of a transformer is designed for 50% insulation life after being loaded to nameplate kVA and running with a top oil temperature of 110 °C for 20.55 years. (180,000 hours) Since your ambient temperature is not constant, and the equipment does not run continuously, the transformer's insulation will last far longer. In most real world applications, if a transformer is not loaded to nameplate, it will theoretically last for more than 100 years. Many electric utilities load their transformers beyond nameplate to take advantage of this overly long life. Motor Inrush: As for the motor starting inrush, the missing factor is how often the motor starts. If it is only seeing an inrush once an hour, the transformer can handle an inrush of 4x nameplate. Your motor's inrush of 1700 amps is 1700 ÷ 760 2.2 times nameplate. According to a transformer manufacturer's table, a transformer can handle an inrush of 2.2 times nameplate more than twenty times an hour. I highly doubt this 450 HP motor is starting and stopping every three minutes. You are good to go with the 500 kVA transformer.
