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Page 49

| Figure 3-7 Network protector for application on low voltage ac network systems. |

| subway type described above, but more often are conventional line-type transformers modified with insulated bayonet-type connections to make them somewhat waterproof and to enable rapid disconnection in the event of fault. |

| For subway-type transformers, usually no lightning arresters are installed. Oil fuse cut-outs are used for smaller transformers, while oil-filled switches or circuit breakers are used for larger sizes; the oil switches generally may not operate under load. In larger units, the switch or disconnecting device is often attached to the transformer case, and may be so arranged to act also as a grounding switch. |

| Substation Power Transformers |

| Substation transformers may be installed either indoors or outdoors. When installed indoors, connections to the units may be made by cables in ducts, by cables carried in trays, or to open busses usually located above the units. Reinforced concrete barriers are installed between units to prevent explosion and fire in one unit spreading to other units. Provision is usually made to take care of oil leakage by means of drains (to safe holding areas) installed in the |

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