Speed is an important operating monitoring parameter for steam turbine units. When the unit speed reaches 110% of the rated speed, the steam turbine should be shut down urgently. To achieve this goal, the unit security system is equipped with an emergency governor in the front bearing box of the steam turbine. The emergency governor impactor is "ejected" by the centrifugal force generated at 110% of the rated speed, which can cause the steam turbine to shut down urgently.

Before the new unit is put into operation or the unit is connected to the grid for each major overhaul, the speed of the impactor action must be measured. To prevent jamming of the impact nozzle, the manufacturer stipulates that the unit should undergo an impact nozzle fuel injection activity test after 2000 hours of continuous operation. However, the installation location of the emergency governor cannot observe the "striking" and "retracting" states of its impactor, nor can it determine the rotational speed when the impactor acts.

The turbine speed/impactor monitoring device adopts microcomputer intelligent technology to solve the problems of speed monitoring and impactor monitoring. It usually displays the turbine speed and captures and records the "high" speed of the unit. When the emergency governor impactor "hits" or "retracts", the internal memory function stores the speed at the time of "hitting" or "retracting" in the instrument. By pressing the "Settings" button on the panel, the "high" speed can be easily displayed in the display window”The rotational speed during "striking" and "retracting".

1、 Technical performance

1. Measurement input

(1) Speed measurement signal: The amplitude of the magnetic resistance speed sensor signal is 50mV~20V (RMS), and the frequency response is 0.5~15KHz;

(2) Impact sensor 1 signal: magnetic resistance speed sensor signal or Hall sensor;

(3) Impact sensor 2 signal: magnetic resistance speed sensor signal or Hall sensor;

2. Parameter settings

(1) Number of teeth: 1-120 (the ratio of the number of signal pulses to the speed value. When the number of teeth is 60, a low of 0.5 revolutions per minute can be measured, and when the number of teeth is 1, only 30 revolutions per minute can be measured. It is set to 60 at the factory);

(2) Alarm value: Level 2 alarm, with alarm I set to 3300 rpm and alarm II set to 3360 rpm at the factory;

(3) Alarm delay: At the factory, it can be set to 1-200 seconds according to user requirements, usually 1 second;

3. Measurement display

(1) Display mode: Four 0.8-inch LED digital tubes display XXXX rpm, with no value hidden at high positions, such as ■ XXX rpm;

(2) Range: 1~9999 rpm, display 1-- when exceeding 9999;

(3) Resolution: ± 1 rpm;

4. Measurement output

(1) Current quantity: 4-20mA current proportional to the speed value, accuracy ± 1%, load ≤ 500 Ω;

(2) Switching quantity: Output alarm I, II and four normally open contacts of the impact sub 1 #, 2 # and other relays, which close when an event occurs. The contact capacity is 2A/250V AC or 1A/28V DC;

5. Warning signal

Panel set alarmWhen an event occurs, the corresponding indicator lights for I, II, and impactor 1 # and 2 # will light up.

6. Environmental requirements

(1) Operating environment: Temperature range of 0 ℃ to+50 ℃, relative humidity<90%, non condensing, non corrosive, and no strong magnetic field;

(2) Storage environment: temperature -30 ℃~+60 ℃, relative humidity<90%, non condensing, non corrosive, and no strong magnetic field;