Hello to all. I need to size a transformer for a small project. Well to be honest, I'm not 100% percent sure that my calculations are correct. I need to install a transformer in a remote location to power up a "high water level" security system. (simply to notify me that i have dewatering pump problems) I currently only have 480 VAC 3 phase at the site. I need approx. 5-6 amps at 120 VAC. I would like a little bit of extra, maybe 10 amps.
Can someone please show me the proper calculations to verify my thinking? Thank you
Merlin, We need more info than you have provided. 5 or 6 amps is overkill for phase loss, high water, low oil, and other typical status monitoring. Are you powering radio transmitters, battery chargers, or other devices that would take additional power? Joe
Yes. It will be powering a cellular transmitter, a 12V backup power supply, and a Hoffman 200 watt cabinet heater. The heater i know is 1.7 amps at 120VAC.The rest of the equipment i am unsure. The engineer only was able to tell me that he only needed about 2 amps. That is why i am trying to slightly oversize it. Does this info help?
Hello, A 3KVA transformer would give you approx. 7.2 Amps @240V, and the primary is approx. 3.6 Amps @ 480V. Next size up is a 4.5KVA, this would give approx. 10.8 Amps @240V, and the primary approx. 5.4 Amps @480V
#181324 - 10/03/0807:04 PMRe: Help with transformer calculations
Thank you much to all. I have since figured it out. It was actually too easy. I thought that was the way it was figured but was unsure. I double checked will a local engineer today and he verified my calculations. Once again thank you all.