Rotors tests

When the torque is determined by the above method, the voltage during the test should be so adjusted that the locked rotor current is approximately equal to the full load current. After the locked rotor test, the resistance of the stator windings should be measured and may also be considered for calculating the I R losses. 

The eapabilities of new eoatings are initially evaluated in the laboratory on speeially designed rainbow rotor test rigs to determine their eorrosion resistanee and effeet on meehanieal properties. 

Fig. 3.40 Effect of velocity upon cast iron in sea-water Rotor test at a water temperature of...

A better cooling efficiency of the compound can be achieved by a lower cooling temperature of the mixing chamber and rotors. Tests were done in order to measure the effect of a decreasing cooling temperature on the silanization efficiency. Figure 29.14 shows the effect of this measure in a... 

It is considered that the error in the estimate of torque obtained using the above procedure is unlikely to be greater than 20%, for rotors with gap ratios in the range 0.05 to 0.2, and with similar ratios of radial to cylindrical rotor surface areas to those of the rotors tested. 

M.L. Wilbur, W.T. Yeager, M.K. Sekula, Eurther examination of the vibratory loads reduction results from the NAS A/ARMY/MIT active twist rotor test, in Proceedings of the American Helicopter Society 58th Anmud Forum (American Helicopter Society, Montreal, 2002)... 

Eddy Current Testing of Turbo Generators Rotors. 

The modern Russian MIA flaw detectors use pulse version of the method [1-3], which peirnits to produce very portable (0.7 - 1.5 kg) and simple instruments, convenient especially for in-service testing. The objects to be tested are multilayer structures of reinforced plastics, metals and other materials honeycomb panels, antenna fairings, propellers, helicopter rotors and so on. In mentioned instruments amplitude-frequency analog signal processing is used. 

In co-operation with LM Glasfiber, a complete section of a rotor blade was produced with a number of well defined defects in order to perform an initial sensitivity test by means of ultrasound, vibrations techniques and real-time radiography. Based on the results of this initial test it was found that automated ultrasonic inspection was the best suited teclmique. In co-... 

Today the coin-tap test is a widely used technique on wind turbine rotor blades for inspection of thin GFRP laminates for disbonded and delaminated areas. However, since the sensitivity of this technique depends not only on the operator but also on the thickness of the inspected component, the coin-tap testing technique is most sensitive to defects positioned near the surface of the laminate. Therefore, there has been an increasing demand for alternative non-destmctive testing techniques which is less operator dependent and also more sensitive to delaminations and disbonded areas situated beyond thicker GFRP-laminates. 

This is a very useful nomogram to determine the performance of a motor with the help of only no-load and short-circuit test results. In slip-ring motors, it also helps to determine the external resistance required in the rotor circuit to control the speed of the motor and achieve the desired operating performance. Slip-ring motors are discussed in Chapter 5. The concept behind this nomogram is that the locus of the rotor and the stator currents is a circle. Consider the equivalent circuit of an induction motor as shown in Figure 1.15, where... 

On a wound rotor motor, the following additional checks are also necessary after removing the slip-ring covers, prior to testing ... 

It is therefore necessary to take precautions during the test to avoid a excessive temperature rise and consequent damage to the windings. For wound rotor motors, speed-torque and speed-current tests may be taken between synchronous speed and the speed at which the maximum torque occurs. 

On the load side, the interrupter is connected through a cable to the equivalent circuit, with the required quantities of lumped resistance and reactance, to represent the motor to be tested, under a locked rotor condition. The circuit would also represent an interruption immediately after a start, to check for the most onerous operating condition for the interrupter to generate the highest surges as discussed earlier. 

Vibration beeomes eritieal in tlie intermediate ranges beeause stmetural members are relatively less massive and the speeds are high enough to mateh the resulting natural frequeneies in some eases. Thorough testing of rotors is essential, and extensive work has been done in this area. 

---