A 1 KVAR capacitor connected to a 240-volt, three-phase electrical system draws approximately 2.4 amps.
Understanding KVAR and Amperage
KVAR stands for kilovolt-ampere reactive, which is the unit of reactive power in an AC electrical circuit. Capacitors are often rated in KVAR for power factor correction applications, where they supply reactive power to inductive loads, thus improving the power factor.
The current (amperage) drawn by a capacitor depends critically on both its KVAR rating and the system voltage. For three-phase systems, the relationship between KVAR, voltage, and current is specific, and knowing the voltage is essential to determine the corresponding amperage.
Amperage for 1 KVAR at 240 Volts (Three-Phase)
Based on common specifications for power factor correction capacitors, a 1 KVAR capacitor operating at 240 volts in a three-phase configuration draws 2.4 amps. This information is crucial for proper electrical design and safety.
Here's a quick reference table showing common KVAR sizes and their corresponding amperage at 240 volts (three-phase):
| KVAR Size | Amps (at 240 Volts, 3-Phase) |
|---|---|
| 1 | 2.4 |
| 1.5 | 3.6 |
| 2 | 4.8 |
| 2.5 | 6.0 |
Calculating Capacitor Amperage
To determine the amperage for a capacitor in a three-phase system, you can use the following formula:
I (Amps) = (KVAR × 1000) / (√3 × V)
Where:
- I = Current in Amps
- KVAR = Reactive Power in kilovolt-amperes reactive
- √3 (square root of 3) ≈ 1.732 (for three-phase systems)
- V = Line-to-line Voltage in Volts
Example Calculation for 1 KVAR at 240 Volts (Three-Phase):
I = (1 KVAR × 1000) / (1.732 × 240V)
I = 1000 / 415.68
I ≈ 2.405 Amps
This calculation confirms the 2.4 amps value provided in the table, reinforcing that the reference values are for a three-phase system. For a single-phase system, the formula would be simpler (I = (KVAR × 1000) / V), resulting in different amperage values for the same KVAR.
Practical Applications and Sizing
Understanding the amperage drawn by a capacitor is vital for:
- Sizing Conductors: Ensuring that the wires connecting the capacitor are appropriately sized to safely carry the current without overheating.
- Overcurrent Protection: Selecting the correct size for fuses or circuit breakers to protect the capacitor and the electrical circuit from overcurrent conditions. Typically, overcurrent protection for capacitors is sized at 150% to 165% of the capacitor's rated current.
- Switchgear and Contactors: Choosing appropriately rated switches and contactors that can handle the capacitor's current, especially considering the inrush current that can occur when capacitors are first energized.
Always refer to local electrical codes and manufacturer specifications when installing or working with power factor correction capacitors.
