Methods for retrofitting a turbomachine

1. A method for retrofitting a turbomachine by replacing a first trip cup of the turbomachine with a second trip cup, the first trip cup including a throw-out arm connected to a first trip cup spring, and the second trip cup including a plunger disposed in a hole defined by the second trip cup and a plunger spring encircling the plunger in the hole, the method comprising:

removing the first trip cup from the turbomachine, the turbomachine comprising a trip paddle;

installing the second trip cup in the turbomachine such that a location of the plunger in the turbomachine is the same as a location of the throw-out arm in the turbomachine when the first trip cup was installed on the turbomachine; and

adjusting a tension in the plunger spring such that, when a speed of the turbomachine exceeds a predetermined value, the plunger actuates the trip paddle located adjacent the second trip cup.

2. The method of claim 1 , wherein the second trip cup is installed such that the location of the trip paddle in the retrofitted turbomachine is the same as the location of the trip paddle when the first trip cup was installed on the turbomachine.

3. The method of claim 2 , wherein the second trip cup is installed such that a location of trip linkages relative to the retrofitted turbomachine is the same as a location of the trip linkages when the first trip cup was installed on the turbomachine.

4. The method of claim 1 , wherein a diameter of the second trip cup is smaller than a diameter of the first trip cup.

5. The method of claim 4 , wherein the first trip cup is enclosed in a first housing and the second trip cup is enclosed in a second housing, the second housing being axially smaller in size than the first housing.

6. The method of claim 1 , wherein installing the second trip cup comprises:

reducing a length of a shaft of the turbomachine,

forming a shaft hole in the center of the shaft, the shaft hole extending along at least a portion of a longitudinal axis of the shaft, and

coupling the second trip cup to the shaft via the shaft hole.

7. The method of claim 6 , wherein reducing the length of the shaft includes cutting the shaft perpendicular to the longitudinal axis of the shaft such that the plunger of the second trip cup is located at the same position in the turbomachine as the throw-out arm of the first trip cup.

8. The method of claim 1 , further comprising:

removing a mechanical flyweight governor and a first set of governor linkages coupling the mechanical flyweight governor to a steam source from the turbomachine, the mechanical flyweight governor including a coil spring disposed around a shaft of the turbomachine and governor flyweights disposed around the coil spring;

installing a mechanical-hydraulic governor in the turbomachine; and

coupling the mechanical-hydraulic governor to the steam source via a second set of governor linkages.

9. The method of claim 8 , wherein a footprint of the second trip cup is substantially the same as or less than a footprint of the first trip cup.

10. The method of claim 1 , wherein the tension in the plunger spring is adjusted such that, when the speed of the turbomachine exceeds the predetermined value, a centrifugal force acting on the plunger exceeds the tension in the plunger spring.

11. The method of claim 1 , further comprising:

removing a mechanical flyweight governor and a first set of governor linkages coupling the mechanical flyweight governor to a steam source from the turbomachine, the mechanical flyweight governor including a coil spring disposed around a shaft of the turbomachine and governor flyweights disposed around the coil spring; and

reinstalling the mechanical flyweight governor and the first set of governor linkages on the turbomachine after installing the second trip cup.

12. The method of claim 1 , wherein the second trip cup is balanced about the central axis of the second trip cup by removing material of the second trip cup diametrically opposite the hole.

13. A method for preventing overspeed operation of a turbomachine including a first trip cup having a throw-out arm connected to a first trip cup spring, and a mechanical flyweight governor coupled to a steam source supplying steam to the turbomachine, the mechanical flyweight governor having a coil spring retained around a shaft of the turbomachine and governor flyweights disposed around the coil spring, the method comprising:

removing the first trip cup from the turbomachine, the turbomachine comprising a trip paddle;

installing a second trip cup in the turbomachine such that a plunger disposed in the second trip cup is at a same location in the turbomachine as the throw-out arm of the first trip cup when the first trip cup was installed in the turbomachine;

removing the mechanical flyweight governor from the turbomachine and a first set of governor linkages coupling the mechanical flyweight governor to the steam source;

installing a mechanical-hydraulic governor in the turbomachine, the mechanical-hydraulic governor being coupled to the shaft and being coupled to the steam source via a second set of governor linkages; and

adjusting a tension in a plunger spring retaining the plunger in the second trip cup such that the plunger is propelled radially outward from the second trip cup and the plunger actuates the trip paddle located adjacent the second trip cup when the turbomachine rotates at a predetermined value, the predetermined value indicative of overspeed operation of the turbomachine.

14. The method of claim 13 , wherein the second trip cup is installed on the shaft of the turbomachine such that the propelled plunger actuates trip linkages adjacent the second trip cup.

15. The method of claim 14 , wherein a location of the trip linkages with respect to the retrofitted turbomachine is the same as a location of the trip linkages when the first trip cup was installed in the turbomachine.

16. The method of claim 13 , wherein a diameter of the second trip cup is smaller than a diameter of the first trip cup.

17. The method of claim 16 , wherein the first trip cup is enclosed in a first housing and the second trip cup is enclosed in a second housing, the second housing being axially smaller in size than the first housing.

18. The method of claim 13 , wherein the tension in the plunger spring is adjusted such that, when the predetermined value is exceeded, a centrifugal force acting on the plunger exceeds the tension in the plunger spring.

19. The method of claim 13 , wherein the second trip cup is installed such that the location of the trip paddle is the same as the location of the trip paddle when the first trip cup was installed on the turbomachine.

20. The method of claim 13 , wherein installing the second trip cup comprises:

cutting the shaft perpendicular to a longitudinal axis of the shaft such that, when the second trip cup is installed, the plunger is located at the same axial position in the turbomachine as the throw-out arm when the first trip cup was installed in the turbomachine;

forming a shaft hole in the center of the shaft and along the axis of the shaft; and

coupling the second trip cup to the shaft via the shaft hole.