Industrial Rackmount Online UPS with Isolation Transformer

There are many situations and cases where transformers is required  and must, or are advised to be, installed in combination with the UPS either internal or added externally. When the reliability and stability requirements are higher, it is recommended to use a transformer-based UPS system in financial, data centre construction, transportation, and general process control (industrial) applications such as oil, steel, and metal.

Isolation of neutral from the source 

This is the most important characteristic of a transformer - it is this characteristic that causes transformers to be useful, necessary, or even legally mandated under certain conditions.Because isolation of the neutral is the key to determining the role of transformers.

Transformer isolation

Transformers are typically represented by the overlapping double-circle symbol shown in below Figure.However, this symbol is a simplification of the actual wiring diagram of a transformer.

The primary, or input, is on the left and three power phases are applied to the transformerwindings (green lines) that are connected in the “delta" configuration as shown by thetriangular shape.

The secondary, or output, is connected in the “wye” (Y-shaped) configuration and consists of three power phases and a centerpoint, or neutral, connection'. There is no electrical connection between the input and output; the power is transferred through magnetic fields between the input and output. What is important to note is that there is no neutra/ connectionon the input. Even if the supply circuit has a neutral connection, it is not used with a delta-wye transformer. The transformer “makes" a new neutral on the output - a new neutral that has no electrical connection to any neutral on the input. in fact, the whole output circuit is at an indeterminate voltage with respect to the input or ground, which is referred to as “floating’Since IT load equipment is grounded, it is never appropriate to supply floating power at an indeterminate voltaae because this could cause insulation failure and other hazards.Therefore, the new neutral on the output of the transformer is connected to ground in virtually all data center applications.

Transformer options for the"single mains" configuration

The single mains system is the most common UPS configuration, used in over 50% of all UPS installations. in smaller systems (below 100kW), it is even more dominant, making up approximately 90% of all installations . The advantage of this system is that it is relatively simple to design and install, yet it provides a bypass that gives a variety of redundancy and maintenance benefits. Small UPS systems below 10 kW typically only have a single input and must be used in the single mains configuration. UPS systems over 10 kW usually provide for dual mains input but are converted to single mains by simply connecting the two mains inputs together. The majority of UPS systems shipped with dual mains input connections actually end up configured for single mains input.

Transformer-based UPS have the advantages of stability, reliability, fewer points of failure,high overload capacity, and impact resistance. Furthermore, the transformer provides galvanic isolation, which is a separation of the input and output supplies that protects the load from spikes, surges, and electrical noise,ensuring equipment safety and precision with minimal temperature rise.