Network transformer vaults are fire retardant enclosures within buildings or adjacent to them that contain two or more power transformers. These transformers are supplied from different subtransmission or distribution lines and are paralleled on their low-voltage side through circuit interrupting devices called 'network protectors.' Historically, users have depended upon the physical design of the vault to limit the risks of fault damage for faults within the vault. This guide is intended to aid those engineers who have re-evaluated the risks associated with faults within network vaults, particularly for those network vaults located within or near high-rise buildings. It also identifies available devices that are being used in network transformer protection schemes. These devices act to sense the fault and initiate fault interruption locally or remotely, thereby minimizing damage and restoration time. These devices are described as to their fault detecting capabilities.
Existing Standards Created by this Working Group