Close


Dimensions in millimeters

Power factor in Fluorescent and HID Circuits
For a pure resistive load in an electrical circuit, the voltage (V) and current (I) are in phase with each other and the overall power factor (cosΦ) has a value of unity. It can also be said that the average power (P) of the resistive circuit is equal to the apparent power (S), ie. P = V x I.

However, in a pure reactive electrical circuit, there is no resistive component; the voltage and current are 90° out of phase, ie. cosΦ = 0.

Electrical circuits containing a combination of both resistive and reactive elements display both average power and apparent power components.

Power factor is therefore the ratio by which the apparent power is multiplied, in order to obtain the average power actually being consumed in the circuit, ie. P = V x I x cosΦ.

For example, a power factor of 0.5 indicates that the circuit has a reactive component having a phase angle of +60° or -60°.  

In common practice most loads are inductive and therefore the current lags the voltage (lagging power factor), whereas a typical capacitive load has a leading power factor.

Fluorescent and HID lamp circuits have an inherent low power factor (around 0.4 to 0.5), due to the control gear inductance. The inductance is in the circuit to limit the current through the lamp, however, in lighting installations where many lamps are used, high input current increases the cost of mains reticulation.

Raising the power factor by means of the inclusion of a capacitor (opposite effect to an inductor) substantially reduces the current drawn from the mains, giving improvement in the reticulation efficiency, which in turn enables a reduction in copper wire size and transformer sizes (the generating equipment).

Most power distribution authorities have a requirement of high power factor (HPF) for lighting installations of generally 0.85 to 0.95 minimum

A typical discharge lighting circuit without power factor correction, eg. 400W high pressure sodium, has a power factor of approximately 0.4. Figure 1 shows the relationship of current and voltage in this application.

This power factor characteristic can be corrected to approximately 0.9 by adding  a capacitor (leading) to the lagging line  current, to cancel the phase shift. Figure 2 illustrates this.

In common application therefore, by connecting a capacitor into the lighting circuit, the power factor can be improved to the values normally prescribed by the regulatory authorities so that practically inductance free operation results.

Capacitor Quality
Assured quality of capacitors is first and foremost and cannot be compromised. Hella uses accepted IEC and BSI Standards as the minimum measure of quality. Production is integrated with an audited Quality System that is accredited to AS/NZS ISO9002 and supported by a technical team and fully equipped laboratory facilities.Hella power factor correction lighting capacitors have been certified by British Standards Institute to BSEN 61048, and BSEN 61049 and has ENEC approval (License no. KM 30180).These standards provide, thorough quality checks of materials and capacitance characteristics, a capacitor that retains its integrity under the required conditions of operation.

Quality Test Program

• Materials / component inspection
• End spray thickness test
• Voltage test
• Capacitance tolerance check
• Dissipation factor
• Physical inspection
• End product batch test
• Endurance test
• Assured Quality Systems (ISO9002 series)
• BSI certification
• ENEC approval
• Testing of the dielectric materials
• in-line 100% capacitance testing
• new automatic ‘AC’ tester
• stud mounting or alternative clip spring accessories.

Top