Overspeed Test Function (Speed Control Screen); Figure 5-27. Overspeed Test Permissives - Woodward 505XT Installation And Operation Manual

Manual 35018V1

Overspeed Test Function (Speed Control Screen)

The 505's Overspeed Test function allows an operator to increase turbine speed above its rated
operating range to periodically test turbine electrical and/or mechanical overspeed protection logic and
circuitry. This includes the 505's internal overspeed trip logic and any external overspeed trip device's
settings and logic. Figure 5-11 shows the screen that is displayed when the 'Overspeed Test' key is
pressed from the Speed Control page. It shows the permissives required to be able to perform an
overspeed test (in the case of a mechanical drive application the Generator Breaker Open is not shown)
Overspeed Test Procedure (from the 505 display)

Be sure the generator breaker is open if unit is a generator drive

Raise the Speed Set Point to the maximum governor setting

If desired, clear the 'Highest Speed Reached' value, to record the highest speed reached during this
overspeed test. (Reset Max key)

This function has a safety timeout to insure the unit does not run in this mode unattended. Once the
mode is entered, the user must begin to raise the speed within 30 seconds. As long as the user is
adjusting the speed the timeout value will be reset.

Timeout value is shown, if it expires the test mode will be aborted and the unit will return to the
maximum governor limit
Woodward

Figure 5-27. Overspeed Test Permissives

The engine, turbine, or other type of prime mover should be
equipped with an overspeed shutdown device to protect against
runaway or damage to the prime mover with possible personal injury,
loss of life, or property damage.
The overspeed shutdown device must be totally independent of the
prime mover control system. An overtemperature or overpressure
shutdown device may also be needed for safety, as appropriate.
505XT Digital Control System for Steam Turbines
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