Apparatus for monitoring and limiting the speed of turbines

Claim 2

Apparatus for monitoring and limiting the speed of a turbine comprising: a. means coupled to the turbine shaft to output a plurality of pulse trains each having a frequency which is equal to the others and proportional to the turbine speed; b. an equal plurality of monitoring channels each channel comprising:

Claim 3

means having a respective one of said pulse trains as in input and providing a first output if the frequency of the pulse train exceeds a predetermined value;

Claim 4

means having a respective one of said pulse trains as in input and providing a first output if the frequency of the pulse train exceeds a predetermined value;

Claim 5

means having two of said pulse trains as inputs, one of which is the same pulse train provided to said means having a respective pulse train as an input, with a different pair coupled to each channel, and providing a second output if said two pulse trains have different frequencies; and

Claim 6

means having two of said pulse trains as inputs, one of which is the same pulse train provided to said means having a respective pulse train as an input, with a different pair coupled to each channel, and providing a second output if said two pulse trains have different frequencies; and

Claim 7

The invention according to claim 1 wherein said means coupled to the turbine shaft comprise; a. a pulse disk coupled to said shaft; and b. a plurality of stationary pulse transmitters adjacent thereto adapted to provide output pulse train in response to rotation of said disk.

Claim 8

The invention according to claim 2 wherein said plurality is equal to three and said means responsive to said final outputs is responsive to shut down said turbine only if final outputs are present from at least two of said three channels.

Claim 9

means having said first and second outputs as inputs and providing a final output in response to either of said first and second outputs; and c. means responsive to the final outputs of said plurality of channels to shut down the turbine.

Claim 10

means having said first and second outputs as inputs and providing a final output in response to either of said first and second outputs; and c. means responsive to the final outputs of said plurality of channels to shut down the turbine.

Claim 11

The invention according to claim 3 wherein said means responsive to shut down said turbine comprises a fast action shut-off valve placed in the input line to the turbine and a plurality of electro-hydraulic means coupled to pairs of said final outputs for operating said valve, said final outputs being such as to remove an energizing voltage from said electro-hydraulic means when present, the removal of energization by both of said pair being necessary to shut down said turbine.

Claim 12

The invention according to claim 4 and further including means for testing said monitoring channels.

Claim 13

The invention according to claim 5 wherein said testing means comprise: a. means for generating a test frequency; b. means for selectively switching the input to each of said channels to either said means for generating a test frequency or a respective pulse train; and c. means for evaluating the proper response of saiD channels to said test frequency.

Claim 14

The invention according to claim 6 wherein a separate test frequency generator is provided for each channel and said means for selectively switching comprise three individual switches having inputs coupled to said test frequency generators and respective pulse trains and further including means to interlock said switches so that only one at a time may provide its test frequency to its respective monitoring channel.

Claim 15

The invention according to claim 7 and further including means for overriding said interlocks.

Claim 16

The invention according to claim 8 wherein said fast acting valve is maintained in an open position in response to a hydraulic pressure which is maintained as long as none of said electro hydraulic means are completely de-energized and further including a second hydraulic pressure source and means to switch from said first to said second hydraulic source, said means for overriding said interlock being operable in response to quick action shutoff valve being coupled to said second hydraulic source.

Claim 17

The invention according to claim 1 wherein each of said frequency comparators comprises: a. means to develop a pulse of a duration which is inversely proportional to the frequency of the input pulse trains; b. means for generating a pulse train at a frequency much higher than that of the input pulse train; c. means responsive to said pulse length to count the number of pulses from said high frequency generating means occuring during pulse length; and d. means to compare the number of pulses counted with a predetermined number and to provide said first output when said counted number is less than said predetermined number.

Claim 18

The invention according to claim 6 wherein said means having said first and second outputs as inputs comprises: a. gating means having said first and second outputs as inputs; and b. output driver means having the output of said gating means as an input and providing said final output as its output.

Claim 19

The invention according to claim 11 wherein said means having one pulse train as an input comprise frequency comparators said means having two pulse trains as inputs comprise frequency detectors and said means for evaluating proper response comprise: a. means responsive to outputs from all of said frequency comparators to provide a third output in response to said test frequency; b. means responsive to outputs from all of said frequency detectors to provide a fourth output in response to said test frequency; and c. means responsive to said third and fourth outputs to store an indication of a malfunction if said outputs are not present a predetermined time after switching said channel inputs to said test frequency, said stored indication being a further input to said gating means.

Claim 20

The invention according to claim 12 wherein each of said second output and said stored indication are coupled to said gating means through a delay.

Claim 21

The invention according to claim 13 wherein said means for testing further include means for performing a dual channel test with said test frequency being supplied to two channels, said means comprising: a. a first gate having the final outputs of two channels to which said test frequency is supplied as inputs and providing a fifth output when both inputs are present; b. a second gate having as inputs the final and second outputs of the remaining channel and responsive to the presence of said second output and absence of said final output to provide a sixth output; c. means to uncouple the second output of said remaining channel from its gating means; and d. a third gate having said fifth and sixth outputs as inputs and providing a seventh output in response to said fifth and sixth outputs being present.

Claim 22

The invention according to claim 4 wherein said said fast acting shut off valve is held in an open position by hydraulic pressure, with the line supplying said pressure coupled to three Lines containing therein respectively first, second and third of said electro-hydraulic means each comprising; a. a spring loaded piston valve which when open couples its respective line to an hydraulic return line; and b. a pair of magnetically controlled valves, which when open supply a pressure to maintain said piston valve closed against its spring pressure, said valves being maintained open by the energization of their magnet coils by final outputs from two of said channels.

Claim 23

The invention according to claim 15 and further including a check valve decoupling each of said pair of magnetic valves whereby both valves must be deenergized to permit said piston valve to open.