Power factor of a series AGL circuit from the real and reactive load of each fixture group.
Each group of fixtures has its own real power and power factor. The tool adds the real and reactive parts separately, then reports the circuit power factor, the apparent power, the voltage across the load and the capacitive reactive power (kVAR) needed to reach a target power factor.
Add one row per kind of load on the secondary side. Enter the real power and power factor of one unit, and choose whether it is lagging (inductive) or leading (capacitive).
| Description | Qty | W each | PF | Type | P (W) | Q (VAR) |
|---|
A placeholder for your own design rule. Used for the correction size.
Real power not in the rows above, such as cable loss, at unity power factor.
Positive for lagging (inductive), negative for leading (capacitive).
Lagging groups give positive Q and leading groups give negative Q, so a capacitive load offsets an inductive one.
Power factors cannot be averaged. The real and reactive parts are added first and the power factor is found from the totals.
In a series circuit the same current flows through every fixture, so the two voltage parts add at right angles.
Here φ₁ is the present angle and φ₂ is the angle at the target power factor. Q_c is the capacitive reactive power to add. It is a size in kVAR, not a capacitor value, and where and how it is applied depends on the CCR and transformer design, so confirm with the manufacturer.
| Item | Value |
|---|---|
| 100 × 45 W at PF 0.95 lagging | P = 4,500 W |
| Reactive power | Q = 1,479 VAR |
| Apparent power | S = 4.74 kVA |
| Series current | 6.6 A |
| Voltage across load | 717.7 V |
| Correction to PF 0.98 | 565 VAR |
It works at the fundamental frequency only. It does not model harmonics from LED drivers, cable reactance, or the effect of brightness steps on transformer power factor. Isolating transformers draw magnetising current, and their power factor falls when they are lightly loaded or the lamp is out, so enter a group for them if you have their data. The power factor at the CCR input differs from the load power factor because of CCR losses and its own reactive current, so use the CCR data sheet for supply sizing.
Quick answers on the power factor of a series AGL circuit and the correction needed to reach a target.
It works out the power factor of a series AGL circuit from the real and reactive load of each fixture group. It adds the real and reactive parts separately, then reports the circuit power factor, the apparent power, the voltage across the load and the capacitive reactive power in kVAR needed to reach a target power factor.
Add one row per kind of load on the secondary side. Enter the quantity, the real power of one unit and its power factor, and choose whether it is lagging (inductive) or leading (capacitive). For each group, P is the quantity times the watts, and Q is plus or minus P times the tangent of the arccosine of the power factor. Lagging groups give positive Q and leading groups give negative Q, so a capacitive load offsets an inductive one.
The apparent power is the square root of the sum of the squares of the total real power and the total reactive power, and the power factor is the real power divided by the apparent power. Power factors cannot be averaged, so the real and reactive parts are added first and the power factor is found from the totals.
It is the apparent power divided by the series current, and full brightness is 6.6 A. In a series circuit the same current flows through every fixture, so the real and reactive voltage parts, which are P divided by I and Q divided by I, add at right angles.
The capacitive reactive power to add is P times (the tangent of the present angle minus the tangent of the angle at the target power factor). It is a size in kVAR, not a capacitor value. Where and how it is applied depends on the CCR and transformer design, so confirm with the manufacturer. The target power factor is a placeholder for your own design rule.
Other real load is real power not in the rows above, such as cable loss, at unity power factor. Other reactive load is entered as positive for lagging (inductive) and negative for leading (capacitive).
100 fixtures of 45 W at a power factor of 0.95 lagging give a real power of 4,500 W and a reactive power of 1,479 VAR. The apparent power is 4.74 kVA, and at 6.6 A the voltage across the load is 717.7 V. Correcting to a power factor of 0.98 needs 565 VAR.
It works at the fundamental frequency only. It does not model harmonics from LED drivers, cable reactance, or the effect of brightness steps on transformer power factor. Isolating transformers draw magnetising current, and their power factor falls when they are lightly loaded or the lamp is out, so enter a group for them if you have their data. The power factor at the CCR input differs from the load power factor because of CCR losses and its own reactive current, so use the CCR data sheet for supply sizing. Fixture power factors are planning assumptions.
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