1.Typical Devices
The following typical turbine protection devices are provided and the description of each and the extent of supply. In circumstances where these devices may initiate a trip, the signals shall be hard wired:
• Local hand trip.
• Remote emergency push buttons.
• Low bearing oil pressure trip.
• Loss of relay fluid pressure trip.
• Externally initiated electrical system trips.
• Overspeed Protection.
• High turbine exhaust temperatures.
• High condenser pressure.
2.Overspeed Protection
To prevent the inadvertent overspeed of the Turbo Generator unit, it is preferred that an established duplex system of overspeed protection shall be provided to trip the unit at 10% overspeed. The system may utilize established mechanical and/or electrical devices.
The facilities provided for testing the overspeed protection systems and the steam admission valves, preferably with full stroking and the minimum reduction of load shall be described.
3.On-Load Testing
Facilities shall be provided for testing the tripping system protection systems and steam valves whilst the set is at part or full load and with the minimum disturbance to the load.
4.High Exhaust Temperature Protection
If water sprays or other devices are included to limit the temperature at the turbine exhaust during transient or continuous low load operation, the full details is required, including the method of control and source of cooling water.
5.High Condenser Pressure Protection
In addition to any vacuum operated unloading and trip gear which may be required, protection against excessive pressure in the condenser shall be provided by an approved means such as lifting or relief discs or bursting diaphragms etc. These shall be sized to discharge full load steam flow with a condenser pressure of less than 0.4 bar (g).
