UPS systems

The use of UPS systems to protect connected consumers offers several advantages for users and operators.

The first and most important advantage is securing the power supply for server landscapes, sensitive measuring electronics and all types of IT, as well as cash register systems, for example. In the event of a power failure, this not only prevents the loss of data, measurement results or the failure of complex systems, but also allows work to continue without interruption thanks to the UPS system. A second advantage, for example, can be that the UPS system restores the „electrical imbalance“ of the house connection and the main building distribution board to a symmetrical load on the three external conductors (L1, L2, L3).

Operator responsibility requires operators of emergency power systems to carry out regular maintenance on electrical systems in accordance with DGUV V3. Proper maintenance should be seen as an investment in the future. No operator of an emergency power system wants a system that fails to take over in the event of a power failure.

Maintenance work is therefore advisable to ensure the reliability and availability of your consumers even in the event of a power failure.

We recommend a maintenance interval of one year, as required by VDE 0105 for electrical installations and electrical equipment.

Battery systems are generally classified as having a service life of 5, 10 or 12 years. However, these are expected service lives under optimal conditions.

Experience shows that often only 70-80% of this expected service life is achieved.

Regular maintenance is crucial for the expected service life of UPS systems. With regular maintenance and routine replacement of necessary wear parts, UPS systems can achieve a service life of >15 years.

This also depends on the load to be supplied and the desired/required bridging time.
Depending on the load to be supplied, standardised requirements may also play a role. In principle, however, every UPS system should be freely accessible and there must be sufficient wall clearance for ventilation. This also depends on the power of the UPS system.

Battery systems in particular are subject to standardised technical requirements due to the gases they emit during heavy charging.

Most UPS systems can be equipped with additional network cards or fault messages, enabling monitoring via SNMP or connection to the building management system.
However, these monitoring devices are often not installed as standard in the UPS system.

Depending on the connected load and the desired bridging time, battery systems can be designed differently. Ideally, internal batteries installed in the housing of the UPS system are sufficient. In this case, the space requirement is minimal. However, with increasing requirements in terms of bridging time and load, it is often necessary to switch to external batteries which must be installed on a separate rack or in a separate battery cabinet.

The bridging time is directly dependent on the connected load and the installed battery system. The battery system for the UPS systems can vary from 1 kVA, so this cannot be answered in general terms.

The required UPS power is directly dependent on the connected loads and their load profile.
In order to correctly dimension the UPS system, the following information is required for the connected loads:

• Performance
• Cosphi
• Inrush current (overload behaviour)

Based on a corresponding load table, the maximum load current and the maximum peak inrush current can be calculated, which serves as the basis for UPS dimensioning.
We recommend a maximum utilisation of approx. 60% for all UPS systems in order to allow for growth and performance reserves.

UPS systems are essentially divided into three categories:

• Offline/standby UPS systems classified as Class 3 according to IEC 62040-3: Provide protection against power failure, voltage dips and surges. This type of UPS system offers the least protection, but is also the most cost-effective option in most cases. It is referred to as an offline or standby system because the system only takes over the supply of the connected loads in the event of a power failure. The switchover time often causes voltage dips of up to 10 ms. IT consumers, such as computers, can often compensate for this delay, so that no power failure is noticeable at the consumer. These types of systems are therefore almost exclusively intended for computers or small IT devices that are not mission-critical consumers.
• Line-interactive UPS systems classified as Class 2 according to IEC 62040-3: Offer additional protection against short circuits in the public grid and line noise. The line-interactive system is considered an intermediate stage between offline and online technology. In contrast to offline UPS systems, systems in this classification also smooth the output voltage so that they protect the connected consumers against voltage spikes and line noise. These types of systems are also suitable for protecting computers and, in some cases, server systems that are not mission-critical consumers.
• Online UPS systems classified as Class 1 according to IEC 62040-3: Provide additional protection against high voltage spikes, frequency deviations, switching spikes and harmonic waves. Online UPS systems offer optimum protection for your consumers and can be used for business-critical applications. Thanks to double conversion technology, there is no interruption in power supply in the event of a mains failure and consumers are supplied continuously. In addition, systems in this category also protect against various types of voltage disturbances. As the DC and AC converters of the UPS system are in continuous operation, a pure sine wave is generated, ensuring that your consumers are provided with an optimal power supply at all times.

An uninterruptible power supply system (UPS for short) is used to supply emergency power to connected loads in the event of a power failure.