Generator Test Procedures

1. English translation:
Table of Content:
1 Objective..........................................................................................................
2 Scopes...................................................................................................................
3 Referenced Documents.......................................................................................
4 Definitions and Abbreviations..............................................................................
5 Determination of inertia by load rejection............................................................
5.1 Conduction of test.............................................................................................
5.2 Evaluation of test...............................................................................................
6 Proceeding in case of deviations .........................................................................
1 Objective
Determination of moment of inertia J, stored energy constant H and acceleration time τJ
of the rotating parts of a machine set by the load drop test.
2 Scope
This procedure for the determination of inertia quantities is valid in the cross function GP
for all types of synchronous machines on site. For determination of inertia the load drop
test is preferred when separate losses for efficiency are not determined by the
retardation method.
Also, in any case load rejection tests are performed by "Protection and Excitation" during
putting into service of the generator.
3 Referenced Documents
IEC 34-4 (EN 60034-4), 70, 71
4 Definitions and Abbreviations
None
5 Determination of inertia by load rejection
5.1 Conduction of test
- The machine operates as a generator on the network.
- The turbine speed regulator is taken out of service
- The generator is regulated to supply active power P1 of 10 to 20 % of the rated load (i.e.
power factor close to cosϕ = 1,0).
- During the test the excitation of the generator remains unchanged
- The generator is suddenly disconnected from the network and the change of speed
with time (curve n = f (t) and/or dn/dt = f´(t)) is recorded with appropriate instruments
(e.g. by means of the ELIN Digital Speed Analyzer DAS).
- At about 10 % overspeed the turbine speed regulator is put back in service
5.2 Evaluation of test
- In the point of nominal speed of the measured speed-time curve n = f (t) the tangent
∆n/∆t resp. the differential quotient dn/dt is determined (Note: The measured curve
normally starts smoothly. dn/dt will be found by extrapolation from the point of inflection
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2. down to nN ). speed and/or its derivation starts smoothly it must be extrapolated down to
rated speed). For determination of the inertia quantities the following fundamental
equations are used (all quantities are here indicated in coherent international SI-units):
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3. 6 Proceeding in case of deviations
Any nominal value, minimum value, maximum value, tolerance etc given in an instruction
is intended to serve for quality control purposes only. In the case of deviations, a
nonconformity report has to be written according to PNG Power Standard
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