There may be some times when an uninterruptible power system may not work properly during a power outage. Due to this, some businesses set up a redundancy system to ensure continuous power to equipment critical for their operations. There are a number of N+1 UPS configurations to ensure there is always a backup to the main UPS used by a business. One of these configurations is the isolated redundant configuration.
An isolated redundant N+1 UPS configuration ensures continuous power for important equipment during a power outage. The first UPS device connects the equipment with the main source of power. On the other hand, the second UPS device is connected to the main power source and isolation module of the first UPS.
Power normally passes through the main UPS before going into the equipment. If the main UPS does not work properly during an outage, power goes through the backup UPS and through the isolation module before going into the equipment.
The isolated redundant N+1 UPS configuration is adaptable and allows two different UPS models or brands to be used. It is also an effective way of ensuring equipment always receive power. But, this configuration has a higher operating cost since the backup UPS continues to use power even though it is not carrying any load.
It is necessary to ensure the secondary or standby UPS is capable of handling the load in case the main UPS does not work properly. Due to this, it is essential to make sure to get a suitable UPS device to use in this particular N+1 UPS configuration. One reason why a UPS may not function properly is the need to replace the battery since it may have reached its shelf life.
References:
http://www.apc.com/salestools/SADE-5TPL8X/SADE-5TPL8X_R3_EN.pdf
http://www.schneider-bgclub.com/catalog/1_Aparatura_NN/4.UPS/Katalozi/Design%20guide%20UPS.pdf