I have a three phase 380V system using 16A MCCB. Phase to Neutral is 220V. I want to install a single phase elevator that has the following specs: Voltage = 220V. Power = 3700Watt. If I calculate the current requirement with the following formula: I = P/V I get 16.81A (3700W/220V). I called the sales to reconfirm and they told me that the required current to operate the elevator is 25A. Now, since I am taking the power from a three phase system, will it provide enough power for the elevator? Can someone please teach me how to calculate the current conversion from 3P to 1P?
UPDATE #1: Thank you for the responses so far. However, if we put in the variables in rapidtables, it gives me just 7A (W=3700, V Type = Line to neutral, V=220, pf=0.8). Please note that my three phase source is 380V and I am using one of the three line to neutral to get 220V for the elevator.
Best Answer
You have 16A MCCB. Safety regulations require that you can only use 80% of that, which is 12.8A. So no matter the single-phase math, you have to do something different.
If I put your single-phase numbers into rapidtables I get 21A. 7A is the three-phase calculation. Hence my comment:
The only real answer is replace the single-phase motor with a three-phase motor.
Apparent Power $$pf = \frac {P} {S} $$ $$S = \frac {P} {pf} = \frac {3,700W} {0.8} = 4,625VA $$
Means a single-phase current of: $$I_{Phase} = \frac {S} {V_{Phase}} = \frac {4,625VA} {220V} = 21.0A $$
So maximum CB is 16A, safety is 12.8A. You cannot supply power to your elevator using a single-phase motor.
Three-phase power:
$$ P_T = \sqrt {3}\ V_{Line}\ I_{Line}\ cos\ \theta$$ $$ I_{Line} = \frac {P_T} {\sqrt {3}\ V_{Line}\ cos\ \theta} = \frac {3,700W} {\sqrt {3}\ \times \ 380V\ \times\ 0.8} = 7.03A$$
Under 12.8A.
At this point, the best advice we could give you is consult an electrician. If you have three-phase power available, it is always best to use it.