Floyd asked in Science & MathematicsEngineering · 1 month ago

# 3 phase power ?

I have trouble understanding 3 phase power only because of the voltages.

If I want to take 3 phase power and step it down. Do I run all three phases through a transformer. If I'm using a three phase panel to run to some equipment, will I use all three phases or can i have single pole breakers or double pole breakers? I still have trouble will three phase

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• Anonymous
1 month ago

Do I run all three phases through a transformer?

You run each phase through its own transformer.  The cores must be separated.  There is no 3-phase transformer.  If you happen to see something that looks like a single unit, it is actually three units.

If I'm using a three phase panel to run to some equipment, will I use all three phases or can i have single pole breakers or double pole breakers?

You will use all three phases.  You can use 3 separate circuit breakers, but they SHOULD be tied together, so if one trips, the other two will be tripped.  A 3-phase circuit breaker is merely three single-phase circuit breakers tied together.

• 1 month ago

If the equipment contains 3 phase motor, then all 3 hot lines from 3 power source are needed to run this type of motor.

Single phase power can be taken out between any hot line and neutral, but the voltage is higher than the common household single phase voltage. Example: a 480V 3 phase power can be taken out 277V single phase power, 277V is too high to be used on  230V appliance, unless it was designed able to run with 277V.

To change 480V 3  phase power into 230V single phase power, a step down transformer is needed. Transformer primary winding accepts 3 phase power ( three hot lines go in ) , secondary winding output has two wires provide 230V.

• 1 month ago

IF your load requires 3 phase power and at a lower voltage, you need 3 transformers.

re breakers, again, depends on the load. If it requires 3 phase power then you need a 3 pole breaker and 4 or 5 wires to it.  If it requires 2 phases then you need a 2 pole breaker.  If it requires 1 phase power then you need a 1 pole breaker.

• 1 month ago