What are Uninterruptible Power Supplies (UPS) – Installation Options?
Single UPS installation
As the description implies, this represents a single uninterruptible power supply installation comprising of the UPS and battery, where the battery can be internal or external and consist of single or multiple strings. Multiple strings can increase the autonomy and also provide greater security of load in the event of a utility mains failure. It should be noted that when the load has been transferred to the maintenance bypass mode it would be unprotected in the event of a utility mains failure.
Hot Standby UPS Installation
This installation uses two UPS modules, referred to as a UPS System; one (A) is directly coupled to the load, the output of the second (B) supplies the reserve input of A. Therefore if UPS A inverter fails, the load is switched to the inverter output of UPS B and is still protected in the event of a utility mains failure. Equally, either UPS can be switched to the maintenance bypass condition with no loss of protection to the load in the event of a utility mains failure. This is used when either the UPS or Generator power protection system are serviced as part of a regular maintenance regime.
Parallel Redundant UPS Installation – N+1
This installation can consist of up to eight modules and can be complete with a static switch module. This type of installation is designed to ensure that when fully loaded there is sufficient capacity to remove one module from service, either for repair or maintenance without altering the integrity of the system. The added advantage is that the system will support an overload situation where redundancy is lost.
Parallel UPS Installation – Sharing the critical load
This installation consists of two or more, modules to support the load (normally up to a maximum of eight, depending on the UPS manufacturer) . The number of modules is designed to support the load and can be a convenient method of installation where one module on its own may be too large to physically fit in the desired location. Also, as in the parallel redundant installation, providing the number of modules has not exceeded the manufacturer’s design requirements, modules may be added as the site load increases.
It should be noted that it is not possible to parallel all types of UPS systems and that the individual modules need to be the same make, module and capacity and will require additional circuitry to provide the parallel control.
Disaster Preventative installation
This usually consists of a substantial UPS system backed by a diesel generator.
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