単相 電力 解析
住宅用および軽商業用の電力負荷を解析します。単純なワット数を超えた総合的なエネルギープロファイルを計算します。
システム入力
単相AC
パラメータを入力すると、結果はリアルタイムで更新されます。
電力三角形の公式
単相AC電力には有効・無効・皮相の3つの成分があり、これらが電力三角形を形成します。
有効電力 (kW)
P = V × I × PF 実際に仕事をする電力 — キロワットで測定されます。電気料金が請求されるのはこの分です。
無効電力 (kVAR)
Q = V × I × sin(θ) 誘導性および容量性負荷によって蓄積・放出される電力です。有用な仕事をせずに電流を発生させ、ケーブル損失を増加させます。
皮相電力 (kVA)
S = V × I = √(P² + Q²) 電源が供給しなければならない全電力 — 有効電力と無効電力のベクトル和です。発電機や変圧器のサイジングに使用されます。
Understanding Single-Phase AC Power
Single-phase AC power is the standard supply for residential buildings and light commercial facilities. Unlike DC, AC voltage reverses direction periodically (50 or 60 times per second), which enables efficient voltage transformation but introduces the concept of power factor — the relationship between the voltage and current waveforms.
The Power Triangle
Real power (kW), reactive power (kVAR), and apparent power (kVA) form a right triangle. The angle θ between the apparent and real power vectors is the phase angle — and the cosine of this angle is the power factor. A PF of 1.0 means the triangle collapses to a straight line: all apparent power is real power.
What Causes Low Power Factor?
- Induction Motors: The most common cause. Motors use reactive power to build rotating magnetic fields. Lightly loaded motors have worse PF than fully loaded ones.
- Transformers at Light Load: The magnetizing current drawn by transformer cores is largely reactive.
- Fluorescent Lighting (older ballasts): Magnetic ballasts introduce significant reactive current. Electronic ballasts largely solve this.
- Variable Speed Drives: Can improve motor PF but introduce harmonic distortion which has its own effects on the supply.
Power Factor Correction
Low power factor can be corrected by adding capacitor banks in parallel with inductive loads. Capacitors supply reactive power locally, reducing the reactive current that must flow from the utility. This reduces cable losses, improves voltage regulation, and avoids utility penalties for industrial customers with PF below 0.9.