PacB Group // Everything You Need to Know About Uninterruptible Power Supply (UPS)

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Everything You Need to Know About Uninterruptible Power Supply (UPS)

An Uninterruptible Power Supply (UPS) is a device that ensures continuous operation of electrical equipment, even when the main power source is disrupted. These devices rely on stored electrical energy to energise loads during outages. The amount of energy stored relative to the load size determines the length of time the electrical equipment can continue to function without grid power, a metric referred to as grid autonomy.

UPS devices require stored energy that can be converted into electricity when the power grid fails. Using rechargeable batteries is the most common method of energy storage, but there are many other storage methods. For example, fossil fuels represent a form of stored chemical energy, and the kinetic energy stored in water can be harnessed by hydroelectric generation systems.

Large-Scale Uninterruptible Power Supply Systems

Dynamic Uninterruptible Power Supply systems are commonly used in large commercial operations with sensitive electrical equipment that require a guaranteed continuous power supply, such as server farms, data centers, and medical facilities. This technology comprises a large rotating flywheel weighing several tons, an alternator that can function as an electric motor, control electronics, and a diesel engine.

During normal operation, when the power grid is available, the alternator, acting as an electric motor, is powered by electricity from the grid to rotate the flywheel. The flywheel stores a significant amount of rotational kinetic energy, which can be used to power loads during a power outage while the diesel engine starts, and the alternator switches from motor to generator mode.

When the power grid fails, Dynamic Uninterruptible Power Supply Systems immediately kick in without interruption. A portion of the energy stored in the flywheel is used to power the generator while it starts up, ensuring that electricity is immediately available from the alternator. The stored rotational energy is used to enable fast start-up of the diesel engine. Within the shortest possible time, the diesel engine ramps up to its rated output, producing electricity via the alternator and stabilising the flywheel. The system ensures there is no gap in power supply and maintains the quality of the electricity, making it a truly uninterrupted power supply. Most of these systems do not require any battery storage.

Battery-Based Uninterruptible Power Supply Systems

Battery-based uninterruptible power supply systems are the most commonly used units due to the unique characteristics of batteries that make them ideal for handling large changes in electrical demand. They can maintain a consistent voltage to an inverter, resulting in clean and stable electrical energy delivery to appliances. Battery-based uninterruptible power supply systems that provide backup power to critical equipment in the event of power outages come, broadly speaking, in three types of uninterruptible power supply systems, namely standby, line-interactive, and online.

Standby uninterruptible power supply systems are the most basic and affordable option, and they work by switching to battery power when the primary power source fails. Line-interactive UPS systems have additional circuitry that regulates voltage fluctuations and protects against power surges.

Online UPS, also known as full-time or double conversion systems, provide the most comprehensive protection as they provide a continuous power supply by running the equipment directly off the battery, which is continuously charged by the AC power source. These systems tend to be the most expensive and require the most maintenance.

Typically, a full-time or full double-conversion system is preferred as it is highly efficient and instantaneous. Incoming utility electricity is usually in the form of alternating current (AC), whereas batteries store direct current (DC) electrical energy. Therefore, a rectifier is necessary to convert the incoming AC electricity to DC to charge the batteries. Similarly, an inverter is required to convert DC electricity back to AC to energise most appliances.

In a double-conversion uninterruptible power supply, electricity continuously flows through the rectifier and inverter, providing a completely isolated output voltage and frequency from the input voltage and frequency. This results in voltage and frequency independent (VFI) devices that are effective in cleaning up fluctuations in grid voltage and frequency. Surge protection devices (SPDs) are usually incorporated to protect against harmful voltage spikes caused by lightning strikes or load shedding in South Africa. Moreover, well-designed uninterruptible power supply systems can correct voltage sags or brownouts before they affect the output.

When the grid fails, the battery delivers energy to the inverter, which provides clean electrical energy to connected appliances. Upon restoration of the grid, the rectifier charges the batteries while the inverter delivers AC electricity via the output to power appliances.

Engage with the Backup Energy Provision Specialists

Industrial-scale backup power provision is a specialist field, and it is vital to choose a partner with a proven track record for providing class-leading backup energy solutions. At PacB, we have a long history of providing professional service and technical excellence. We are recognised as leaders in the power-generation industry in Southern Africa. We provide large-capacity industrial diesel generators as well as a comprehensive range of UPS and renewable energy systems.

Our reliable MAKELSAN range of uninterruptible power supply systems is class-leading and comes in a vast range of sizes. Whether you need a small or large unit, our range will provide a solution. Units come in sizes from 1 kVA to 800 kVA. MAKELSAN uninterruptible power supply systems feature true Online-Double-Conversion Technology (Class VFI-SS-111) for the highest level of power protection. They utilise IGBT PWM Rectifier and Inverter Technology and DSP Control for efficient and reliable operation. The MAKELSAN range comes with high-efficiency ratings of up to 93% and can be customised as frequency converters. With advanced battery management, unlimited parallelable modules, and selectable numbers of batteries, the MAKELSAN uninterruptible power supply systems offer unparalleled flexibility. Boasting a small footprint and easy maintenance, these units have advanced communication capabilities and come equipped with an SNMP card and AS400 for perfect generator compatibility. They also have short-circuit, neutral, and overload protection, as well as static and manual bypass operation. Equipped with a 500 real-time event log with detailed parameters, these units are an ideal power-protection solution.

Don’t hesitate to contact us at PacB today for all your uninterruptible power supply system needs. Our competent technical team is always available for telephonic or on-site assistance to support our products.