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Page 58

| For small transformers, usually pole-mounted, the load supervision is only a very approximate operation. |

| Larger Installations |

| For larger, industrial or station-type units, such supervision may consist of more complex, permanently installed meter installations and associated relay and alarm circuitry (Fig. 4-1). As mentioned previously, internal pressure relays are sometimes installed on the larger, more critically important and expensive transformers. |

| When such supervisory measures fail to anticipate transformer troubles, protective devices such as fuses and circuit breakers operate to disconnect the transformer, usually before extensive damage occurs. |

| Figure 4-1 Switchboard for larger installation. |

| External Inspection. |

| Much can be learned of the condition of the transformer from an external inspection. The condition of the bushings, if broken, cracked or chipped, may not only be caused by vandalism, but may be a sign of flashover caused by |

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