IEC 60034-2-2:2010 pdf – Rotating electrical machines – Part 2-2: Specific methods for determining separate losses of large machinesfrom tests- Supplement to IEC60034-2-1.
NOTE I The test macbin. may b. dnvn by its normal pnm. mover, ..g by P.lton turbine when th. water supety to the rurwier can be cut off Instantly.
NOTE 2 Excitation from a nicchanic.aity.couplad eicatir is not rcornmndd, but may be p•rnwttsd when the value ot the devIation 04 speed 6 does not eaceed 0.05. Losses In exciters coupled to the shaft of the lest machine are to be taken into account
The bearing temperatures shall be adjusted to the normal temperature at which the bearings operate with rated load, by adjusting the coolant flow.
The air temperature shall be adjusted, whenever possible, to the normal temperature at which the windage loss measurement is required by throttling the air coolant flow. Testing preparation
Retardation tests shall be conducted as a series without interruption, whenever possible. It is recommended that the series start and finish with retardation tests of the test machine unexcited.
All tests shall be repeated several times at the preset rated values of open-circuit voltage or short-circuit current. The arithmetic mean value obtained from each series of measurements shall be assumed to be the appropriate loss value of that category of loss.
Select a value of 6 (the per unit deviation of rotational speed from rated speed) which shall not be greater than 0,1 and may have to be less than this, depending on the characteristics of the machine. Tests
Rapidly accelerate the test machine to a speed above N (1 + ). Disconnect the machine from its supply Source. Sufficient time delay shall separate the switching off of the supply and starting the measurements to allow electromagnetic transients to decay.
During deceleration to siN (1 — %) place the test machine in the required condition, according to the following tests:
When moment of inertia is known.
a) running unexcited;
hi running open-circuited, excited at rated voltage;
C) running with the armature terminals short-circuited, and the excitation set to give the rated armature current.
NOTE P,a an alternate, tests may be carried out at various vakae within limits of the order of 95 V. to 105 V. 01 either th, rated voltage or rated short-cirwit current
Additional tests, when the moment of inertia is unknown, shall be conducted at the same values as determined in b) and C) according to either d) e) or I).
d) with the field suppressed. connect the test machine to a transformer previously set under no-load condition and excited to the preset values of current or open-circuit voltage;
c) with the field suppressed, connect the test machine to a transformer previously set under short-circuit;
f) with the field suppressed, simultaneously load the exciter or the auxiliary generator with a ballast resistance at a predetermined load.
Each retardation test shall be repeated at least twice.
NOTE ExcitaUoi shod be povded by a separate source accordinQ to 7.2 2 2. Separation of additional and short-circuit losses
The sum of the 12R loss and the additional loss in the armature circuit is determined as the difference of losses measured in the third and first test. Separation of this sum into components, if required, is done by subtracting from it the PR loss in the armature circuit calculated from the armature circuit resistance corresponding to the test temperature. Measurement of losses in bearings
Losses in common bearings should be stated separately, whether or not such bearings are supplied with the machine.
The losses In bearings and thrust bearings shall be subtracted from the total sum of the mechanical losses. If the tested machine uses direct-flow cooling of the bearings, those losses are distributed between the tested machine and any other coupled to ii mechanically, such as turbine, In proportion to the masses of their rotating parts. If there is no direct-flow cooling, the distribution of bearing losses shall be determined from empirical formulae.
7.3 CalorimetrIc method
7.3.1 General
The calorimetric method may be used to determine the efficiency of large electrical rotating machinery:
a) either by the determination of the total loss on load, or
b) by the determination of the segregated losses.