A New Paradigm in Power Quality for Powering Tactical Systems Adaptive Power Factor Correction (APFC™) by NOVA Power Solutions

Most commercial electronic equipment contains some form of power factor correction, intended to ensure that a reasonably high power factor is maintained. However, these power factor correction circuits are typically fixed rather than adaptive, designed to optimize power factor only when the equipment is operating at a maximum electrical load. 

When the electrical load of this equipment decreases in the course of normal operations, the input power factor degrades significantly, and fixed power factor correction circuitry is not able to compensate for the lighter loading. This is the primary reason that NOVA Power Solutions engineers strongly recommend not over-provisioning a power protection solution, as the decrease in power factor translates to increased energy usage and higher costs. 

To address this, NOVA Power now offers adaptive power factor corrected inputs for its SRNT and SRHF family of systems. Adaptive power factor correction adjusts the power factor correction circuitry to compensate for changes in equipment electrical loading. This means much higher efficiency in provisioning of electrical power throughout a system, a critical consideration in the shipboard and other tactical environment.

Power Factor 

To understand Power Factor Correction (PFC), we must first understand power factor. 

The relationship between real power, reactive power, apparent power and the power angle φ is generally represented by the power triangle (Figure 1). 

Power factor is an expression of energy efficiency, and expressed as a percentage, or decimal. Power factor is the ratio of real power (or actual power), measured in watts (W), to apparent power (or total power), measured in volt amperes (VA). 

Real power is the power consumed or utilized in an AC circuit. Apparent power or total power, also known as demand, is the measure of the amount of power needed to operate equipment. Apparent power is found by multiplying (VA = V x A). The result is expressed as VA units. 

Power factor expresses the ratio of real power used in a circuit to the apparent power delivered to the circuit. Power Factor is also expressed as the cosine of the phase angle (φ) between current and voltage.

The lower the percentage, the less efficient the power usage is. A 95%, or .95, power factor demonstrates more efficiency than a 75%, or .75, power factor. For example, according to Figure 2, only 70% of the energy provided by the electrical system is being used to produce useful work or real power (kW). 

Poor power factor means that you are using power inefficiently. This is important to consider because it can result in:

Large kVA rating and size of electrical equipment, higher costs,

Large line losses (Copper Losses) due to current increase,

Greater conductor and component size and higher costs,

Heat damage to insulation and other circuit components,

Poor voltage regulation and large voltage drop,

Reduction in the amount of available useful power, increase in power consumption (Increase in power bill, increase in fuel consumption on board the ships or tactical mobile platforms)

Poor power factor increases the overall cost of a power distribution system because the lower power factor requires a higher current to supply the load devices. 

Causes of Low Power Factor

The main cause of low power factor is Inductive Load. Following are examples of inductive loads that cause low power factor which constitute a major portion of the power consumed in industrial and tactical military environments:

Single and three phase induction motors (for instance gun turrets, antenna motors, pumps on board the ships) 

Varying load in power system

High intensity electrical discharge lamps

Transformers

Harmonic currents

Unlike resistive loads that create heat by consuming kilowatts, inductive loads require current to create a magnetic field, and the magnetic field produces the desired power. The total, or apparent power required by an inductive device is a composite of the following:

Real power (measured in kilowatts (kW)).

Reactive power, the non-working power caused by the magnetizing current required to operate the device (measured in kilovolt-ampere-reactive (kVAR)).

Reactive power required by inductive loads increases the amount of apparent power (measured in kVA) in the electrical distribution system. The increase in reactive and apparent power causes the power factor to decrease. 

Power Factor Correction

Power factor correction is a circuit or power supply designed to correct for inefficiencies and to increase the ratio of apparent power to real power. The higher the power factor, the more efficiently the equipment will operate. 

Following are the merits and benefits of improved Power factor;

Increase in efficiency of system and devices

Low voltage drop, better voltage regulation

Reduction in size of a conductor and cable which reduces overall cost 

An increase in available or real power

Reduced line losses 

Appropriate size of electrical machines (transformer, generators etc.)

Low power consumption kWh (or low fuel consumption in ships, remote tactical or other mobile military platforms

Better usage of power system, lines, and generators etc.

Saving in energy as well as rating and the cost of the electrical devices and equipment is reduced 

The efficiency offered by good power factor correction can also be explained by an analogy. In Figure 3, an efficient latte pour results in more consumable coffee (real power) and less froth (reactive power). The coffee portion represents power that can be used for useful work while froth is the non-working power required to operate a device.

Adaptive Power Factor Correction (APFC™)

The adaptive power factor correction paradigm maximizes efficiency by ensuring a continuously high-power factor despite fluctuations in the equipment’s electrical load. Now offered in NOVA Power Solutions’ SRNT systems, adaptive power factor correction yields, as compared to fixed circuitry, much higher efficiency in provisioning of electrical power throughout the system. In a shipboard, remote, mobile or other tactical environment, this translates to important advantages, longer on-station times, and lower degradation of the cable plant, all of which reduce maintenance cycle times and cost, while increasing mission readiness

NOVA Power Solutions provides custom design rugged continuous power systems hardware, with built-in always-on power conditioning, to protect sensitive defence equipment ideal for harsh tactical environments land, maritime and remote satellite ground stations that require such reliability and resilience. For the past eight years, the company has collaborated with local Turkish system integrators and manufacturers, especially in locally developed indigenous defence projects.

For questions or inquiries, readers may contact Süleyman BAYRAMOĞLU, NOVA Power Solutions Business Development Manager for EMEA, at suleyman.bayramoglu@novapower.com