Welcome to the first in a series of articles focusing on electrical calculation basics. This month, we'll discuss the most fundamental of calculations — those for current (I) and kilowatts (kW). We'll also show you how you can do these calculations “in your head,” with very reasonable accuracy, through the use of constants.

#### Discuss this Article 25

I have a boiler with no data, but I measured the phase current for each phase. The reading is 19A at 380V? How do I calculate the power?

P = 1.73 x V x I x PF =1.73 x 380 x 19 x 0.80 = 9.9kW

or

P = 1.73 x 380 x (3 x 19) x 0.80 = 29.9kW

Which is correct calculation?

how will I know the ideal load on each circuit (single phase electricity?)

at 1 hp how much current will take 1 phase motor and 3 phase motor approximately please tell me.

hi,

i am having one doubt

if we had not divided 3 phase equally and powered on the current supply what will happen?

I have a 3 motor pump,1hp each single phase.what amperes of breaker that i use for the 3 motor pump?

Sir,

I have single phase lighting load,single phase AC load,single phase geyser load,single phase heater load.How to convert from 1 phase to 3 phase load

Hi ,

I would like know about the calculation of 3-phase line to line, line to neutral and line to ground current. I want to know what the difference between these three is. I design canteen and the supply is line to neutral, 3-phase. My calculation is like this:

I got the initial current ab, bc and ac.

How calculate the total current line to line? line to neutral? line to ground?

Thank you,

JDC

if using single phase 250 volts 200 amps going into transformer / converter running 50 hp motor out power generation of 40 kph what would consumption be per hour or day. would there be surplus or not.

I have one problem. How can I select cable size for 0.75 kW single phase motor? Please give the formula and also define the derating current formula.

Please tell me how to calulate the UPS required for a machine that is using 2.5hp, 3-phase AC motor with 230V 60 Hz AC input.

And please tell me how many Watts it will consume and current.

Please help.

I have the following motor:

1) 40hp, eff=94%, PF=0.83, SF=1.15, Amp=58.4, 3-phase, ambient Temp=55degC.

2) the ampere reading was 44.5 and V=385, but the air flow is low. so the contractor change the pulley.

3) new reading are Amp=68.5/69/68.6 for the 3 wire.

Are the new readings safe for motor or not? And i need to know the FLA for this motor because is not mentioned in the name plate.

I am having trouble nailing down a load calculation.

If,

I = 539

E= 460

PF = 91.0

kW= 39,033.1942

For a 3-Phase electrical motor, what would be my my total draw?

Dear sir,

I have 3-phase, low speed suguna motor. I have single-phase power at 240V. Please suggest a single-phase power to 3-phase converter box.

Dear sir,

I have five power sockets in a circuit. The socket mentions 16A/250V. What will be the VA or kVA of this circuit and which breaker should I use in panelboard?

Thanks

How many amps would 415V / 3-phase / 144A convert to in single phase / 240V?

I have a water pump (5.5kW) and a lift (7.5kW), 3-phase, 380V. I want to operate them using a generator. What capacity of generator is needed, taking in consideration the starting amps?

Hi everybody,

I'm a technician working in Dubai. I have some machinery. One of them is 75kW, 415V, 122A. What size circuit breaker should I use to keep it safe running? And wire size? It's a new setup.

Thanks for your help.

Can anyone help me please?

I need to find out what is the formula to calculate the 'Overload Setting' on a 3-phase motor, based on or assuming (for example) that the 3-phase voltage is 415V, and the rating of the motor is Example A - 800W or Example B - 1,000W.

I am looking to gain a clear understanding of how to be able to do this type of calculation, and any help with this would be greatly appreciated!