WHAT IS POWER FACTOR?
Power factor is an expression of energy efficiency and is a measure of how effectively incoming power is used in your electrical system. It expresses the ratio of real power actually used in a circuit to the apparent power delivered to the circuit and is usually expressed as a number between 0 and 1. The higher the power factor, the more proportion of your supplied power is being used for useful work and the more efficient your site is at utilising the supplied power.
It’s important because you may be paying for power that you cannot use to power your equipment. Improving your power factor results in less current being drawn, less heat and greater longevity of your electrical system. Improving your power factor may also result in significant savings on your electricity costs.
Learn more about power factor
ARE YOU PAYING FOR ELECTRICITY THAT YOU ARE NOT USING?
Improving your power factor can result in considerable savings on your power bills. For example, think of a glass of beer, made up of the thirst-quenching liquid and the froth.
The drinkable liquid represents Real Power, the power that performs the actual work. Think of this as the satisfying liquid in the beer you’ve paid good money to drink. The froth represents Reactive Power, the power that energises your equipment. It doesn't do any useful work – it doesn’t quench your thirst.
As you pay for the whole glass of beer, you want more of the liquid and less of the froth to get value for money. Poor power factor is like a beer with too much froth, with the froth representing wasted energy (money). By improving your power factor, most or all of the power supplied that you are paying for is being used for productive work. By not paying for the froth, you save money.
Case Study showing cost-saving
SAVING MONEY BY IMPROVING POWER FACTOR
The Electricity Utilities and Retailers are changing the way they bill you.
Traditionally, our electricity has been charged according to a kW (kilowatt) demand tariff which is commonly known as ‘real power’. This means that you are charged for the electricity that you actually use. The change is that you will now be charged according to a kVA (kilovolt-ampere) demand tariff which is commonly known as ‘apparent power’ (or real power plus re-active power). Every electrical facility consumes an amount of re-active power. This energy is considered ‘wasted’ as it does not perform useful work. The changes are currently being rolled out across Australia.
Improving your power factor can result in considerable savings on your power bills.By installing Power Factor Correction equipment, you will be able to reduce your Peak kVA Demand Tariff and this will result in significant savings in your electricity bill
Reducing your electricity costs with power factor correction
HOW CAN junke HELP YOU?
Power Factor Correction. Contact us for a free site appraisal and no obligation assessment to see if you can save money on your energy costs.
Performance
|
SVG (Static VAR Generator) |
Switched Capacitor Bank System |
---|---|---|
Mode of Operation |
The SVG detects the load current on a real-time basis through an external CT and determines the reactive content of the load current. The data is analysed and the SVG’s controller drives the internal IGBT’s by using PWM signals to make the inverter produce the exact reversing reactive current of the corresponding load reactive current. | The system detects the load current on a real-time basis through an external CT and determines the reactive content of the load current. The data is analysed and the system’s controller switches in the required amount of reactive current in steps, depending on the amount of reactive current available to it in that moment from the capacitor bank. |
Compensation method |
The SVG performs as a controlled current source, thus obtaining a power factor of 0.99 lagging whilst avoiding over-compensation and under-compensation. |
Traditional PFC systems use capacitors in groups. Their output current is in fixed steps (50kVAr, 25kVAr, 12.5kVAr, 6.25kVAr) which usually leads to over or under-compensation. |
On-going costs |
The SVG does not require a maintenance contract. It simply requires that the unit is kept clean. Aside from the initial purchase cost, on-going costs are negligible. |
Capacitor bank style PFC systems are typically sold with a maintenance contract which is an on-going monthly charge to pay for regular maintenance and the cost of replacement parts like the capacitors, contactors, fuses, etc. |
Response Time |
The complete response time of the SVG is less than 15ms and the dynamic response time is less than 50μs. The SVG can track the dynamics of the load and compensate instantaneously in almost real-time. |
Capacitor bank style PFC systems take at least 20ms – 40s to perform compensation depending upon whether the switching is done via a solid state switch or a contactor. |
3 Phase Operation |
The SVG measures and provides dynamic kVAr compensation throughout all three phases. |
A switched capacitor bank style PFC system measures only one phase and provides stepped kVAr compensation only to that phase, irrespective of what the other two phases need. |
Load Imbalances |
The SVG can, if required, balance the phase currents to further lower the peak kVA presented to the grid (or energy authority). |
Capacitor banks with Delta connected capacitors cannot balance the load currents in a three phase system. |
Wall-Mount Solutions |
They can be parallel connected in a ‘Master / Master / Master’ type arrangement. This ‘plug and play’ system provides the safest continuous operation. If one unit is shut down for whatever reason the remaining modules remain in operation until the alarm is attended to or the situation resolved. |
Limited range. |
Resonance |
The capacitance of the SVG does not require the installation of a de-tuning reactor. Performing as a current source and an active compensation device the SVG has been designed to not be affected by resonance. |
Traditional PFC systems are affected by resonance, which is detrimental to the capacitors. To lower the risk, de-tuning reactors are introduced into the circuit to lower the resonant frequency below that of the lowest harmonic in the circuit. |
Harmonics |
The SVG can operate in harmonically rich environments of up to 15% THDV without detriment to itself or its performance. |
Even with the use of de-tuned reactors, harmonics play a major role in shortening the lifespan of capacitors and contributing to their destruction. |
Load Type |
The SVG can correct both a lagging and a leading power factor, as well as work with a traditional capacitor type PFC system to eliminate over and under compensation. |
Capacitor bank style PFC systems can only compensate for inductive loads. |
Operation at low voltages |
Designed with an active compensation circuit. Therefore the voltage of the grid has little influence on the compensation capacity. The output of reactive current matches the working conditions even when the voltage of the power grid is low. |
Capacitor output is subject to the voltage of the grid, so if the grid voltage is low the output of the capacitors will be low, resulting in a decline in available compensating capacity, under-compensation and possible fault conditions. |
Sizing |
The compensation capacity of the SVG is the same as the installed capacity. Therefore for a given compensation effect, the capacity of the SVG may be 20%-30% less than that of a standard capacitor type PFC system. |
To better suit the changing dynamics of the load, a traditional capacitor type PFC system needs to be oversized and to have a greater number of smaller steps to better suit the application. This increases the cost. |
ROI (Return on Investment) |
The SVG does not require a maintenance contract. It simply requires that the unit is kept clean. Aside from the initial purchase cost, on-going costs are negligible. |
When estimating the ROI for capacitor bank style PFC systems, apart from the initial cost of the system, other factors over the medium to long term must be considered, including the on-going cost of the maintenance contract and replacement parts like the capacitors, contactors, fuses, etc. |