The kVA rating will be listed on the transformer's nameplate, which is usually on the front of the transformer. The 480v to 120v is irrelevant, because many Transformers with different kVA ratings convert 480 volts to 120 volts. The kVA ratings can be different and thus affect the rated current through the transformer.
The voltage 277 volts is a three phase line to neutral voltage of a 480 volt system. What is needed for the protection of the transformer is a two pole breaker from the 480 volt CDP (Central Distribution Panel). The breaker will be sized to the KVA of the transformer. The wire will be sized to the breaker plus 25%. The electrical code requires that on motor and transformer feeders, they be sized to 125% of the total current capacity of the equipment.
You need to mention the Load connected to find the current.
480 volts and 60ohm impedence current = volt/impedence current=480/60 current=8ampeares
Oil is used to cool the transformer. There is no telling what the transformer in question uses without knowing the specific part number and looking up the specification.
In short, probably. Transformers step power up or down by a multiplicative factor based on the number of turns in the two transformer coils. Therefore, if you put more voltage in you're going to get a proportional increase in the voltage out.
The transformer operates in reverse. In other words, a step-down transformer becomes step-up, and vice-versa. Example: a transformer with a 480 volt primary and 120 volt secondary: Ratio = 4:1 (480/120=4) Fed in reverse - Ratio = 1:4 Apply 120 volts, output is 480. Note that if you accidentally reverse the transformer, still feeding it with 480 volts, the output would be 1920 volts (480 X 4 = 1920) - probably not a good thing!
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This 480-v three-phase transformer probably has a 208-v three-phase secondary which has 120 v from each line to neutral. In that case the primary current is 0.433 times as much as the secondary current, so 100 amps in the secondary means 43.3 amps in the primary.
v/i=r so 120/0.25=480 480 ohms is the resistance
The voltage 277 volts is a three phase line to neutral voltage of a 480 volt system. What is needed for the protection of the transformer is a two pole breaker from the 480 volt CDP (Central Distribution Panel). The breaker will be sized to the KVA of the transformer. The wire will be sized to the breaker plus 25%. The electrical code requires that on motor and transformer feeders, they be sized to 125% of the total current capacity of the equipment.
480 V INPUT / 120 OUTPUT 480 V INPUT / 120 OUTPUT 2KV/AMPERE MEANS 2KVA 2000/220=9.0909 AMPS SO 229X9.0.909=2000 WATS OR 2KW
25% of 480= 25% * 480= 0.25 * 480= 120
You need to mention the Load connected to find the current.
0.25 of 480 is 120. 480 multiplied by 0.25 (1/4) is 120 or 480 divided by 4.
The LCM is 480.
120/25 x 100 = 480 Therefore, 120 is 480 percent of 25.
Yes, the more voltage you put in the more you get out. If the transformer is a 2 - 1 ratio and you put 240 in you get 120 out and when you put 480 in you get 240 out. Magnetic field strength and voltage have a direct relationship. +++ The field strength is actually a function of current, although as you say, increasing the voltage will increase the current hence the magnetic field.