1-4
BE1-32R, -32 O/U GENERAL INFORMATION
Figure 1-4. Power Relay Distribution Protection
Example 5, Delayed Electrical Trip
On large steam units, where overspeeding is a prime concern, a reverse power relay can be used to supervise
electrical tripping (field and main ac breakers) for selected relay operations (e.g. non-electrical trips, loss of field
relay), as shown in Figure 1-5. The reverse power relay delays breaker tripping until trapped steam has been
removed from the piping. In this case, as separate direct-tripping anti-motoring relay can be used to protect for
situations not related to an automatic shutdown of the unit.
Figure 1-5. Single-Phase, Non-Electrical Trip Supervision
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