| Hardly anyone will argue that the need for | | | | services. |
| uninterruptible power supplies (UPS) is on the rise as | | | | Some critical loads, especially sensitive medical and |
| ancient power supply infrastructures creek under the | | | | scientific equipment, require tight voltage and frequency |
| weight of increasing demand for energy worldwide. | | | | regulation and this is only possible from the |
| But why do power protection load types need to be | | | | continuously running inverter of an on-line UPS. |
| categorised? | | | | Essential loads do not need the quality of supply |
| Firstly, business managers must assess what UPS | | | | provided by a UPS and can be powered directly from |
| loads are in terms of their criticality to the continuity of | | | | a generator. This will allow the overall size of UPS to |
| operations in the event of a power cut. Usually, | | | | be reduced. Non-essential loads do not require any |
| uninterruptible power supply loads are categorised as | | | | power protection at all. |
| critical, essential and non-essential. | | | | The Effect on the Electrical System of Critical UPS |
| Another crucial assessment at the design stage of a | | | | Loads. In terms of type, UPS loads are referred to as |
| UPS system is how these loads are synergised, i.e., | | | | either linear or non-linear, depending on how they draw |
| which loads affect other loads? | | | | their current from the mains power supply waveform. |
| Computer loads, in terms of a retail business for | | | | They will be inductive, capacitive or resistive. |
| example, may affect other systems that are part of | | | | An inductive load is one the waveform of which lags |
| facilities management. This may include security | | | | the voltage waveform and has a potentially high |
| cameras, door entry systems, lifts, escalators, PoS | | | | in-rush current at start-up. Examples of this type of |
| terminals, kiosks, cash machines and so forth. In a | | | | load are SMPS (the most common form of power |
| warehousing business, computer loads may also have | | | | supply unit in use today and the type of computer |
| a significant bearing on the ability of the business to | | | | loads most often found behind today's power-hungry |
| handle both in-bound and out-bound goods. All of this | | | | data centres), transformer or motor. This may be |
| needs to be taken into account when assessing the | | | | tempered by a soft-start facility. |
| criticality of UPS loads. | | | | Capacitive loads are those that lead the voltage |
| UPS loads also need to be categorised in terms of | | | | waveform with potentially high in-rush current at |
| their electrical draw and the effect it has on electrical | | | | start-up. An example of this is the latest high-end |
| systems; whether they are capacitive, inductive or | | | | server technology such as Blade of Edge Servers. |
| resistive. This will have a bearing on the size and type | | | | A resistive load is one that has no inductance or |
| of UPS system to be installed. | | | | capacitance, an example being a resistive load test |
| Load Categories. Critical loads directly affect the ability | | | | bank heater element where the device typically has no |
| of an organisation to operate and must either be kept | | | | initial switch-on surge and the current drawn rises |
| running when the mains power supply fails or be | | | | immediately to a steady running state. |
| powered down in an orderly manner to prevent | | | | Whether a load is inductive, capacitive or resistive will |
| systems crashes, data loss or corruption, and | | | | determine its power factor and this in itself greatly |
| life-shortening hardware damage. Their routine | | | | influences the overall size of the UPS and generator |
| operation can also be interrupted when the mains | | | | (or alternative source of back-up power) to be |
| power supply is polluted. | | | | installed. By convention, an inductive load is defined as |
| Essential loads provide secondary support services | | | | a positive reactive power and a capacitive load is |
| and may be required for health and safety reasons or | | | | defined as a negative reactive power. However, |
| to maintain ambient temperature. Whilst requiring a | | | | power factor is never shown as positive or negative; |
| form of back-up in case of mains power supply failure, | | | | rather it is displayed as either lagging or leading. |
| they do not require uninterruptible power and can be | | | | Assessing load types, how they are synergised, and |
| allowed to fail or ride through the time it takes for a | | | | their effect on electrical current is critical to correctly |
| generator (or alterative back-up system) to start up. | | | | sizing and designing UPS solutions to get maximum |
| Examples include air-conditioning, heating and | | | | power protection and value for money. Expertise from |
| emergency lighting. | | | | specialists like Riello UPS, whose business is to fully |
| Non-essential loads are those that an organisation can | | | | comprehend UPS loads and load types, cannot be |
| afford to lose when the mains power supply fails. For | | | | overlooked. More detail can be found in a fantastic |
| example, general lighting and non-essential printing | | | | book on UPS - The Power Protection Guide. |