JPH065001B2 - Turbine vibration monitor - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a vibration monitoring device for measuring and monitoring shaft vibration of a high-speed rotating machine such as a steam turbine / generator, and particularly to a turbine unnecessary when an earthquake occurs. The present invention relates to a turbine vibration monitoring device that prevents trips and the like.

[Technical background of the invention]

The most important thing in the operation of a high-speed rotating machine such as a steam turbine used in a power plant or the like is to suppress its shaft vibration to an appropriate level in all operating conditions.

By the way, a sign of excessive shaft vibration often appears when the turbine is started or when the load changes, and the vibration is generally one of many operation monitoring items that requires particularly strict monitoring.

In addition, as nuclear power plants grow in capacity,
Since it plays an important role as a base load in Japan, there is a strong demand for improved reliability of its main equipment, such as rotating machines such as turbines and generators. Therefore, the measurement of vibration, which is an index of the reliability of rotating machinery, is extremely important, and the vibrometer used there must also have high reliability. Similarly, a vibration monitoring device that uses a vibrometer as a sensor must also have high reliability. For example, if there is an emergency stop of the steam turbine due to a malfunction of the vibrometer, it will make social life difficult. It is inevitable to give it, and sufficient attention must be paid to the configuration of the vibration monitoring device.

From such a viewpoint, the steam turbine generator used in the thermal power plant and the nuclear power plant,
The shaft vibration of the turbine rotor and generator rotor is constantly monitored,
When the vibration amplitude value exceeds a certain value, an alarm is issued to notify the operator of the abnormality, or when the vibration amplitude value becomes larger and exceeds the set value, the steam stop valve of the steam turbine inlet is stopped suddenly. An automatic trip device that automatically trips (stops operation) when closed is installed for safety.

FIG. 1 is a diagram showing a general vibration measurement point of a turbine generator, in which a high-pressure turbine rotor 1, a low-pressure turbine rotor 2, and a generator rotor 3 are flange-connected as one shaft system, and Bearings 5 are supported on the journals 4 in the front and rear of the rotor body.

By the way, a normal vibrometer 6 is mounted on the bearing 5 as shown in FIG. That is, the outer cylinder 9 of the vibrometer 6 is fixed to the bearing stand 8 installed on the base stand 7.
A detection rod 11 urged in the bearing 5 by a spring 10 is concentrically provided in the outer cylinder 9, the tip of the detection rod 11 is pressed against the journal portion 4, and the base end of the detection rod 11 is further provided. A detector 12 is attached to the.

When the journal portion 4 vibrates, the vibration is transmitted to the detector 12 by the detection rod 11 that is in contact with the journal portion 4. In the contact type vibrometer 6 as described above, since the detector 12 is usually composed of a speedometer or an accelerometer, the absolute vibration of the journal section 4 should be detected as the speed or acceleration through the detection rod 11. You can Therefore, the output from the vibrometer 6 is integrated by the integrator 13 and converted into a displacement signal.
As the type of the vibrometer 6, there is also a non-contact type that uses a displacement meter that can directly detect a change in relative displacement between the bearing base 8 and the journal portion 4. By the way, the displacement signal is rectified by the rectifier 14, changed into the vibration amplitude change which is the absolute value of the displacement, and then input to the comparison and determination device 15.

The comparison / determination device 15 has a built-in arithmetic circuit for comparing the amplitude signal with a predetermined vibration limit value, that is, an alarm value or a stop value. An alarm signal is output to 16, and when the vibration further increases and exceeds the stop value, a stop signal is output to the trip device 17. Therefore, the alarm device 16 or the trip device 17
Respectively, an alarm is issued according to the output of the comparison and determination device 15 to inform the operator of the abnormality, or the turbine generator is tripped.

The comparison / determination device 15 includes a vibrometer 6 attached to each bearing 5.
The output signal of each comparison and determination device 15 is input to a common alarm device 16 and trip device 17 as shown in FIG. 3, and one vibration monitoring device is provided. It is configured.

The vibration monitoring device in such a turbine protects the turbine generator from vibrations caused by internal factors of the turbine generator itself such as unbalanced vibration of the rotor, rubbing, oil whip, and steam whirl, The main purpose is to improve safety. By the way, since the vibrometer 6 is an absolute vibrometer attached as shown in FIG. 2, not only when the journal portion 4 vibrates but also when the whole including the bearing base 8 vibrates, the vibration is not generated. You will sense it. Such a phenomenon does not occur unless a considerably large external force acts, but there are earthquakes and the like that cannot be ignored.

By the way, generally, as shown in FIG. 4, the bearing base 8 is fixed to the foundation base 7, the foundation base 7 is installed on the mat 18, and the mat 18 is placed on the ground 19. There is. Therefore, when an earthquake occurs, the vibration is transmitted from the ground 19 to the mat 18, and the bearing base 8 and the journal portion 4 are further excited via the foundation base 7.

When the vibration system including the turbine / generator and the turbine base is modeled, as shown in FIG. 5, it corresponds to the total mass of the high-pressure turbine rotor 1, the low-pressure turbine rotor 2, and the generator rotor 3 in FIG. It can be replaced by a general spring-mass system including a mass 20, a spring 21 corresponding to the rigidity of the turbine / generator base 7, and a damper 22 representing a damping term. Assuming that the mass corresponding to the total mass of the rotor is M, the spring constant of the spring 21 is K, and the damping coefficient of the damper 22 is D, the response of the turbine / generator to the external force x ₁ = A ₀ sin ωt applied to the mat 18 Is
The ratio of the response amplitude A ₂ to the input amplitude A ₀ is as shown below.

ω ₀ = Natural frequency of foundation platform including turbine generator If the damping is small, if the frequency component of the seismic wave and the natural frequency of foundation platform match, that is, η = 1
In the case of, the vibration of the turbine generator mounted on the foundation is large. The exciting force varies depending on the vibration characteristics of the base 7, but may reach about 2 to 5 times the exciting force of the mat 18. Further, since the vibrometer 6 is designed to detect the vibration displacement even if the entire bearing base 8 vibrates, even if an external force such as an earthquake acts on the foundation base, the vibration displacement amount becomes the stop value. When it reaches, it is still a trip device
A stop signal will be issued to 17 and the steam turbine will trip.

The relationship between vibration displacement and acceleration is expressed by the following equation.

δ = α × 9800 / (2πf) ² (2) where δ = vibration displacement α = acceleration f = frequency As can be seen from this equation, even if the acceleration is small, the large displacement is generated when the frequency is low. Occurs. For example, when the acceleration is 0.05 G and the frequency is 5 Hz, the displacement is 0.5 mm. As described above, the seismic wave is amplified by being transmitted through the foundation table and is input to the bearing stand 8. For example, when the vibration response magnification is 2, when the mat 18 is excited by a ground motion of 0.025 G, The bearing base 8 is vibrated at 0.05 G, and its displacement is amplified to 0.5 mm. Therefore, if this exceeds the stop value, the comparison and determination device 15 outputs a stop signal and the steam turbine trips. Since many frequencies are included in the seismic wave and the amplitude response magnification varies depending on each frequency as can be seen from equation (1), such a simple calculation is not sufficient, but the result of this study is at least about 0.025G. Even if a small earthquake occurs, the steam turbine will trip and the power transmission from the plant will stop.

The above is the case where the vibrometer 6 directly senses the seismic wave or the amplified seismic wave through the bearing base 8 and reaches a trip. In addition to this, the seismic wave acts as an exciting force on the bearing base 8 and the bearing 5. A trip value may be reached due to a temporary large amplitude induced as a result of applying a forced external displacement to and from the rotor journal 4.

Although such a phenomenon has been clarified by a recent case analysis, even if it is a complete vibration measurement system, there is still the possibility of an unintentional turbine trip when an earthquake occurs. . On the other hand, if a large-capacity turbine / generator that is responsible for the base load trips unnecessarily, it will have a great impact on the power system, leading to a wide-area total blackout and causing social confusion.

That is, FIG. 6 is a diagram showing an example of the configuration of a general normal vibration limit value used in the comparison and determination device, in order to notify the operator of the occurrence of an abnormal state at a certain level of the vibration amplitude value. Alarm value 24, trip value 25 that outputs a trip signal to the automatic trip device 17 that notifies that the amplitude value at which the unit should be stopped due to the progress of an abnormality, and trip signal is output even if the stop value is reached It is configured with a backup trip value of 26 to deal with a malfunction. Therefore, when the vibration amplitude value becomes larger than the trip value 25 or reaches the backup trip value, as shown in FIG. 7 (a) or FIG. 7 (b), the unit trips via the time limit timer 27. A signal is output and the unit is tripped. The time limit timer 27 is a delay element that is generally inserted in order to prevent a miss strip due to an erroneous signal, and one having a setting of 1 to 2 seconds is usually used.

However, in such a device, for example, when an earthquake occurs, the shaft vibration value may easily reach the large vibration trip value as described above. Although the operation is continued without tripping for 2 seconds, for an earthquake that continues for more than this time, even if the time limit timer 27 expires, the earthquake or the large axis vibration phenomenon caused by it will not occur. It continues, and eventually the unit trip signal is output to the automatic trip device 17 and the turbine / generator comes to a stop. Moreover, in the very early stage of the turbine / generator shutdown process, the earthquake ends and the large shaft vibration phenomenon disappears, and the trip factor is canceled. Furthermore, even if there is no other trip factor other than this large shaft vibration, steam trip In this case, the turbine / generator is in vain. Furthermore, once a trip occurs, the turbine / generator cannot rejoin the system without a restart operation, but normally it is necessary to wait until the starting conditions for the plant are complete for the next start. ,
During that time, power cannot be generated, and the resulting loss is enormous.

Therefore, there has been a demand for a turbine vibration monitoring device capable of accurately coping with a shaft vibration phenomenon caused by an earthquake even if it occurs.

[Object of the Invention]

In view of such a point, the present invention has an object to obtain a turbine vibration monitoring device capable of minimizing the chance of a turbine trip without causing an unnecessary turbine trip due to the occurrence of an earthquake. And

[Outline of Invention]

The present invention compares a vibration detection device that continuously detects vibration of a rotating shaft and a vibration signal detected by the vibration detection device with a predetermined vibration limit value, and the vibration signal exceeds the vibration limit value. In the case of a turbine vibration monitoring device that has a comparison and judgment device that outputs a trip signal for automatically stopping the unit, and an automatic trip device that automatically stops the unit by inputting the trip signal, In the output circuit, a timed timer that stops the trip signal in consideration of earthquake measures or for a certain period of time is installed in parallel with the timed timer for normal operation with a short set time. It is characterized by switching to activate the timed timer in consideration of earthquake countermeasures. Are those that trip was not allowed to occur.

Example of Invention

Embodiments of the present invention will be described below with reference to FIGS. 8 to 14.

8 (a) and 8 (b) are block diagrams for a unit trip due to a large vibration phenomenon in the present invention. The trip signal output circuit considers the duration of the large shaft vibration phenomenon when an earthquake occurs. A time limit timer 30 having a time limit of 4 to 6 seconds is provided. This timed timer 30 has a fundamentally different concept from the timed timer 27 shown in FIG. 7 (a) or (b), and only the shaft vibration of the turbine / generator due to the earthquake at the time of the earthquake occurs. The purpose of this is to prevent trips due to the ground, and the set time is not the usual short time for erroneous signal judgment, but the ground 19, the mat 18, the foundation stand 7, the bearing stand 8, the bearing 5 due to an earthquake. In consideration of the fact that the seismic radio waves are sequentially amplified to finally appear as a large shaft vibration phenomenon of the turbine / generator rotor, the time is set to a long time of 4 to 6 seconds in consideration of the duration of this phenomenon.

That is, generally, the duration of the main motion of the earthquake motion is expressed by the following equation.

log (T ₀ ) = 0.3 × M-1.2 (3) Where, T ₀ : Duration of main motion of earthquake motion M: Magnitude of earthquake (magnitude) Figure 9 is a diagram of this formula. Yes, for example, magnitude 7 indicates that strong earthquake motion continues for about 10 seconds.

By the way, when a seismic wave enters the turbine / generator foundation 7, it resonates at the frequency of the seismic wave and the eigenvalue of the turbine / generator foundation, and the seismic wave component near this frequency is amplified. It The degree of this amplification varies depending on the frequency component of the seismic wave and the characteristics of the turbine / generator foundation, but is generally about three times. Furthermore, the seismic waves amplified by the turbine / generator foundation stand pass through the bearing stand, the bearing, and the bearing oil film, and are further amplified 1.5 to 2 times, and finally the earthquake input to the turbine / generator foundation stand 7 It becomes 4.5 to 6 times larger than the size of and enters the turbine / generator rotor.

However, the strong seismic wave entering the turbine / generator rotor is a frequency component that resonates with the turbine / generator foundation block and bearing block, and the duration of a strong earthquake with this frequency component is as short as 5 to 6 seconds. I'm getting sick. Further, it is when the seismic wave has a frequency component close to the critical speed of the turbine / generator rotor that the shaft / generator rotor causes a large axial vibration phenomenon due to the amplified seismic wave. Usually, it is a plant that has a four-pole rotor like a nuclear turbine that tends to be a problem in an earthquake, and has a critical speed near 15 Hz. Although this frequency component is not the main component of the seismic wave, it is a constituent component and is amplified because it exists in the range that exists as the eigenvalue of the turbine / generator foundation, but the time duration after amplification is at most 4-5 seconds. Is. That is, it can be said that the time period during which the large-scale vibration of the shaft and the large-scale vibration of the turbine / generator rotor is affected by the occurrence of an earthquake is generally 4 to 5 seconds.

By providing the trip signal circuit with the timed timer having the set time as described above, it is possible to prevent the turbine / generator from tripping unintentionally when an earthquake occurs. In addition, after the earthquake, unless there is an abnormality in the main body of the turbine / generator or other devices, the large shaft vibration phenomenon will be converged in an extremely short time, and then normal operation will be performed. On the other hand, if an abnormality occurs inside the equipment due to the earthquake, the large axis vibration phenomenon continues even after the earthquake has converged, so a unit trip signal is output to the automatic trip device 17 and the turbine / generator stops, The installation of the timed timer 30 does not impair the protection function.

In addition, according to the configuration of FIG. 8 (a) or (b), the long-time timer 30 operates even during normal operation other than during an earthquake, so that the set time is 4 to 6 seconds. Even if the shaft vibration exceeds the large vibration trip value due to internal factors,
The turbine generator will not trip. This is more effective than the conventional device from the viewpoint of preventing the mistrip due to an erroneous signal, but conversely, the trip timing is delayed from the viewpoint of ensuring safe driving. Therefore, long time timer 30 4 ~
The set time of 6 seconds is also an allowable limit time in which the operation can be continued without tripping in consideration of such drawbacks.

FIG. 10 shows a combination of a conventional short-time timer 27 for preventing trip due to an erroneous signal and a long-time timer 30 which is the basis of the present invention. In other words, the trip signal output circuit has
A short time timer of 2 seconds and a long time timer of 4 to 6 seconds are provided in parallel with each other.

Then, normally, when the shaft vibration exceeds the operation limit value, a large vibration trip signal is output, and the short time timer 27 waits for 1 to 2 seconds to check the situation. Even after the time timer expires, the large shaft vibration trip signal is output. In the case of occurrence of, the unit trip signal enters the trip device 17, and the turbine / generator is stopped. However, when the large axis vibration phenomenon is due to an earthquake, an earthquake occurrence signal is output by the earthquake detection device 31, the unit trip signal circuit based on a simple large axis vibration trip signal is automatically cut off, and a long time timer 30 is provided. It is designed to switch to the existing circuit. Therefore, a long timer of 4 to 6 seconds during an earthquake
30 monitors the large axis vibration phenomenon caused by the earthquake.

Therefore, if there is no abnormality in the turbine / generator body or other equipment due to the earthquake, the large vibration phenomenon will end and the trip signal will disappear due to the end of the earthquake. Although it does not stop, if a large vibration trip signal is output even if an abnormality occurs and the earthquake ends, the unit trip signal enters the trip device 17, and the turbine / generator stops. In this way, you can usually prevent missrips due to erroneous signals, and in the event of an earthquake, unless something abnormal occurs, you can easily prevent trips due to an earthquake,
The operational reliability of the generator can be improved.

FIG. 11 is a modified example of FIG. 10, in which the shaft vibration large trip signal is divided into two stages, a large vibration trip signal which is a normal operation limit value and an auxiliary backup trip signal, and the signal is detected by the OR circuit. The trip circuit can be effectively used as in FIG. 10 regardless of which signal is detected.

FIG. 12 is a diagram showing another embodiment of the present invention. When an earthquake occurs, the short-time timer 27 is switched to the long-time timer 30 by the earthquake signal detected by the earthquake detection device. At the same time, a second long timer 32 is provided for reverse switching from the long timer 30 to the short timer 27. The setting time of the second long time timer 32 is the duration of the earthquake itself, which is the duration of the earthquake itself until a low ground motion of about 10 gal is set, and is set up to about 30 seconds.

With such a configuration, switching from the short-duration timer 27 to the long-duration timer 30 is performed by the output of the seismic signal from the seismic detection device 31, but the reverse switching is performed by the second. Because of the long time timer 32, it is possible to change the intensity level of the earthquake that gives the timing of switching and reverse switching. For example, in order to limit the opportunity to use the timed timer 30 for a long time, the detection level of the seismic detection device 31 is increased to a seismic level that may cause a large shaft vibration of the turbine / generator. The second long timer 32 is the time until the earthquake motion is sufficiently attenuated for safety once switched.
Can be used to delay reverse switching.

Such usage can raise the set level of the seismic detection device, which makes it easy to design the instruments that compose it and is also effective in preventing malfunction.
Since the use time of the long timed timer 30 can be lengthened, it is possible to more effectively reduce the chance of trip due to earthquake motion.

In addition, as shown in Fig. 13, when both an earthquake occurrence signal and a trip signal due to large turbine / generator shaft vibration are output, a short timed timer 27 to prevent trips due to an erroneous signal Long timed timer 30 for
When the earthquake ends or the large axis vibration phenomenon disappears, reverse switching is performed and a short timed timer 27
The circuit that leads to the unit trip may be restored. In this case, it is possible to minimize the chance of using the timed timer 30 for a long time.

Needless to say, the embodiment of the present invention is characterized by the use of the long timed timer 30 for preventing an unnecessary trip of the turbine generator due to an earthquake.
Here, the use of the timer in the trip circuit is a delay command for trip operation, and its safety must be evaluated sufficiently. However, as described above, the internal abnormality of the turbine / generator that appears as shaft vibration due to the earthquake is realized as the set time of the long timed timer 30, as described above. No consideration was given to the direct damage to the aircraft. The strength of turbines / generators is usually designed based on seismic design standards.However, in the event of an earthquake more than that considered, there is a risk that the turbine / generator itself will be damaged. Therefore, it is necessary to issue a trip signal based on the earthquake itself and stop the turbine / generator earlier than the unit trip based on the abnormal signal output by the shaft vibration monitoring and other state monitoring. For this purpose, as shown in Fig. 14, a certain limit value is set for the magnitude of the earthquake, and when an earthquake of a certain magnitude occurs, an earthquake large trip signal is output and this signal The unit trip signal may be issued with priority over the signal of.

By the way, as described above, the vibration limit value for normal operation in the comparison / determination device is set at the steam turbine / power generation level in response to an increase in vibration caused by internal factors such as non-uniform vibration of the rotor system, rubbing, oil whip, and steam whirl. It is usually set well below the strength limit of the bearings bearing the rotor system, in order to protect the machine and usually to detect an upward trend from vibration levels as early as possible. That is, in general, the danger of large vibration is in the contact between the rotating part and the stationary part, and this tendency becomes divergent due to the thermal bending phenomenon of the rotor that occurs as a result of local heating of the rotor. The limit value is set as low as possible.

On the other hand, the response of the rotor system at the time of an earthquake corresponds to the case where the vibration system as shown in Fig. 5 is subjected to the forced external displacement from the stable position. Has extremely high rigidity, and it has been clarified that the rotor system, the bearing and the bearing stand move together. In such a case, it is sufficient to take measures on the vibrometer side so that the vibrometer does not detect the seismic motion, but if the seismic motion appears as it is as relative vibration between the rotor and the bearing,
This is the case where the natural frequency of the vibration system shown in the figure is relatively close to the predominant frequency of an earthquake, which is said to be 8 to 10 Hz. At this time, the rotor wave is temporarily superimposed on the seismic wave and the frequency corresponding to the natural frequency. It has a large waveform and causes a large vibration that exceeds the large vibration value for normal operation.
Such an example is seen in a 4-pole large-capacity steam turbine / generator, and since it is a unit with a rated speed of 1500 or 1800 rpm, it often has a natural frequency near 12 to 15 Hz. It will be greatly affected by the earthquake.

However, the large vibration at the time of an earthquake may be as large as the bearing clearance in terms of vibration value, but since its frequency is the frequency of the seismic wave or the natural frequency of the system, the rated rotational frequency It is characterized by being sufficiently lower than. Therefore, even if rubbing is caused by this vibration, it does not lead to local heating of the rotor and does not bend because it does not have a rotation synchronizing component. In this way, the large vibration excited by the seismic wave will be converged if the earthquake motion converges, and there is almost no possibility of developing into a divergent vibration phenomenon, and it can be said that it has an extremely stable property.

It is not rational to apply a short-time timer of 1-2 seconds for the purpose of early detection of divergent vibrations and prevention of trips due to erroneous signals against such vibration phenomena. The probability of reaching a trip immediately and automatically stopping the unit is extremely high.
If the vibration in this case is not divergent, it is considered that the limit of safe operation is the strength of the bearing that supports the rotor system. It is not necessary to trip even if the vibration limit value set for normal operation monitoring is exceeded. Therefore, in such a case, killing the normal vibration monitoring system by the timer until the end of the earthquake is a rational method that can give an appropriate instruction to the operator with a simple system. Even if a divergent vibration develops during the seismic motion, if the long time timer expires before and after the earthquake converges as described above, the normal shaft vibration will automatically occur. In order to return to the monitoring, the automatic trip device is activated at that time, and it is possible to prevent further vibration increase, so that there is no possibility of damaging the device body at all.

〔The invention's effect〕

As described above, in the present invention, the trip signal output circuit is provided with a time limit timer for stopping the trip signal in consideration of earthquake countermeasures or for a certain period of time in parallel with the time limit timer for normal operation. Since the time timer for operation was switched to operate the time timer in consideration of earthquake countermeasures, it prevents accidental trip operation against axial vibration increase due to earthquake motion and closes to the design limit on the strength of equipment. The operation can be continued. Therefore, the turbine / generator will not trip due to a small earthquake, the operating durability can be significantly improved, more stable power supply can be performed, and confusion due to a large power stop can be prevented. can do. In addition, during normal operation, the timed timer for normal operation can be operated to prevent missrips due to erroneous signals.On the other hand, there is no delay in trip timing from the viewpoint of ensuring safe driving. Since it only has to be done, the configuration can be extremely simple.

[Brief description of drawings]

FIG. 1 is an explanatory view of a shaft system of a turbine, FIG. 2 is an explanatory view of a structure for mounting a vibration monitor of a vibration monitor on a bearing, FIG. 3 is a schematic system diagram of a conventional turbine vibration monitor, and FIG. 5 is a vertical cross-sectional view of the bearing portion of the turbine generator including the base,
FIG. 7 is a diagram modeling the vibration system of the device of FIG. 4, FIG. 6 is an explanatory diagram of vibration limit values of the turbine vibration monitoring device, and FIG.
(a) and (b) are block diagrams showing the concept of conventional vibration monitoring, and FIGS. 8 to 14 are block diagrams showing the concept of monitoring in the vibration monitoring device of the present invention. 5 ... Bearing, 6 ... Vibrometer, 7 ... Foundation stand, 8 ... Bearing stand, 15 Comparison judgment device, 17 ... Trip device, 27 ... Short time timer, 30 ... Long time timer, 31 ... Earthquake detection device .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Hisa 2-4, Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Tokyo Shibaura Electric Co., Ltd. Keihin Office (72) Inventor ▲ Hitoshi Sakaki, Tsurumi-ku, Yokohama-shi, Kanagawa 2-4 Suehirocho Tokyo Shibaura Electric Co., Ltd. Keihin Office (72) Inventor Shigeru Takamiya 1-6 1 Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Shibaura Electric Co., Ltd. Tokyo Office (56) Reference JP-A-60-132003 (JP, A)

Claims (3)

[Claims] 1. A vibration detecting device for continuously detecting the vibration of a rotating shaft, and a vibration signal detected by the vibration detecting device is compared with a predetermined vibration limit value, and the vibration signal indicates the vibration limit value. In a turbine vibration monitoring device having a comparison and judgment device that outputs a trip signal for automatically stopping the unit when it exceeds, and an automatic trip device that automatically stops the unit by inputting the trip signal, In the output circuit, a timed timer that stops the trip signal in consideration of earthquake measures or for a certain period of time is installed in parallel with the timed timer for normal operation with a short set time. A turbine vibration monitoring device characterized in that the timed timer is switched to operate in consideration of earthquake countermeasures. 2. A second long time timer for performing reverse switching from a timed timer in consideration of earthquake countermeasures to a timed timer for normal operation is provided. Turbine vibration monitoring device. 3. Switching from a timed timer for normal operation to a timed timer that stops trip signals for a certain period of time in consideration of earthquake countermeasures when both a large vibration axis signal and an earthquake signal are output. 2. The turbine vibration monitoring device according to claim 1, wherein reverse switching is performed when any one of the signals disappears.