This standard specifies end modal test analysis method of turbine-type generator stator winding and evaluation criteria and end vibration measurement method of turbine-type generator stator winding and evaluation criteria.
This standard is applicable to turbine-type generator with rated power 200MW or above and rated speed 3000r/min and 3600r/min.
Before the turbine-type generator leaves factory, or during new machine handover, or the generator in thorough repair, stator winding end modal test shall be carried out and inherent frequency of lead wire shall be measured. Where abnormal situation occurs in operation (for example, withstand sudden short circuit, coil abrasion, looseness, etc.), carrying out modal test and lead wire inherent frequency measurement are advised.
In type test, where severe looseness occurs after the stator winding end is impacted by short circuit or the winding end has unqualified elliptical mode shape modal, vibration measurement shall be carried out to stator winding end.
Turbine generators below 200MW may execute by reference to this standard.
The imported units may also execute according to this standard.
2 Normative References
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties who enter into agreement according to these specifications are encouraged to research whether the latest editions of these documentations are applied or not. For undated references, the latest edition of the referenced document is applicable to these specifications.
GB/T 2298 Mechanical Vibration and Shock-Terminology
3 Terms
Terms determined according to GB/T 2298 and the following ones.
3.1
Natural frequency
The frequency of free vibration of linear system.
3.2
Frequency response function
a) The ratio of steady state output vector to input vector during simple harmonic excitation.
b) The ratio of output Fourier conversion to input Fourier conversion during transient excitation.
c) The ratio of output and input cross spectrum to input autospectrum during stable random excitation.
3.3
Modal test analysis
Vibration test analysis carried out to determine system modal parameter. Generally, work out frequency response matrix by excitation and response relation first; then identify modal parameter by methods such as curve fitting.
3.4
Model parameter
Modal characteristic parameter, namely inherent frequency, mode shape, modal mass, modal stiffness and modal damping of each step of the vibration system.
3.5
Mode shape
A mode shape of given vibration modal of mechanical system refers to the described figure by maximum displacement value caused by points on neutral plane (or neutral axis) deviating their equilibrium positions. Generally, the mode shape value of each point shall be generalized according to the deviation value of chosen point.
3.6
Elliptical mode shape
The mode shape of which the shape is elliptical.
3.7
Amplitude
The maximum value of sinusoidal vibration.
Synonym: amplitude.
3.8
Peak value
The maximum value of vibratory magnitude in given interval.
3.9
Peak to peak value
The algebraic difference between the maximum values of vibratory magnitude.
