របៀបគណនារក kVA ត្រង់ស្វូ ១ហ្វា និង ៣ហ្វា

 

ការគណនារកkVA 

Single Phase KVA Calculation

The formula for finding the required KVA or transformer size for single-phase power is the following:

Volts x Amps / 1,000 = KVA

Based on the equation, one would need to plug in the proper load/output (secondary) voltage and current (amps) to compute for KVA. Note that load voltage is not the same as line voltage, which is also known as primary voltage or input.

Example: Find the KVA or transformer size for load voltage of 120V 1PH and a load current of 50 amps.

120 x 50 / 1,000 = KVA

6,000 / 1,000 = KVA

= 6 KVA

 

Three-phase KVA Calculation

Businesses that require three-phase power need to add an extra component in the formula to arrive at the correct transformer size, i.e., square root of 3 (√3) or 1.732. This figure is a constant found in three phase, as the phases do not generate the same amount of power (simultaneously). Furthermore, three-phase transformers handle three lines of AC power, with each of the three lines 120 degrees out of phase from the other two lines.

With this in mind, the new formula can be found below:

Volts x Amps x √3 / 1,000 = KVA

Example: Find the KVA or transformer size for load voltage of 240 3PH and a load current of 60 amps.

240 x 60 x 1.732 / 1,000 = KVA

= 24.94 KVA (or 25 KVA after rounding up)

ខា្នតkVA របស់ត្រង់ស្វូ

For referencing, below are the standard KVA sizes for singe-phase transformers:

1, 1.5, 2, 3, 5, 7.5, 10, 15, 25, 37.5, 50, 75, 100, 167, 200, 250 and 333 (KVA)

Taking our answer from the single-phase example above – 6 KVA or 7.2 KVA (with 20 percent spare capacity); we can see that there is no standard single-phase equivalent available. As a solution, simply round up to the next standard single-phase KVA size: 7.5 KVA.

Standard sizes for three-phase transformers:

3, 6, 9, 15, 30, 45, 75, 112.5, 150, 225, 300, 500, 750 and 1,000 (KVA)

Donwlaod Excel

Downlaod formula

Credit by : www.larsonelectronics.com