Trip cup for overspeed control

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.

A method for retrofitting a turbomachine by replacing a first trip cup of the turbomachine with a second trip cup and by replacing a mechanical flyweight governor with a mechanical-hydraulic governor, 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 and a first housing enclosing the first trip cup from the turbomachine, the turbomachine comprising a trip paddle;
• installing the second trip cup in the turbomachine, the second trip cup being installed such that, when a speed of the turbomachine exceeds a predetermined value, the plunger propels radially outwards from the second trip cup and deflects the trip paddle disposed adjacent the second trip cup, the trip paddle being disposed such that a 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;
• removing the mechanical flyweight governor from the turbomachine and a first set of governor linkages coupling the mechanical flyweight governor to a steam source supplying steam to the turbomachine;
• and
• installing the mechanical-hydraulic governor in the turbomachine, the mechanical-hydraulic governor being coupled to a shaft of the turbomachine and being coupled to the steam source via a second set of governor linkages.