Compensator characteristics

Thus also an unbalancing of the original electrical compensation characteristic of the isoelectric state, will be the result, which will increase in the order 1—2y 1—3, 1—4. Of course this unbalancing will in itself diminish the efficiency of the mutual... 

A number of meter designs have been developed based on this principle. Some are shown in Eigure 17. Certain advantages ate claimed for each, but all share a number of characteristics. Perhaps the most important property is a full-scale deflection on the order of 0.001 mm. The sensors for these meters are extremely sensitive, stable, and capable of being temperature compensated. 

Take-Ups. A take-up is requited on a belt conveyor to ensure the proper belt tension at the drive pulley and along the conveyor, as weU as to ensure the proper troughing contour between idlers. A take-up is also needed to compensate for changes in belt length caused by elastic stretch during start-up, and any elongation characteristics of the belt that occur over a period of time. 

Rotaiy stem-valve designs are normally offered only in their naturally occurring characteristic, since it is difficult to appreciably alter this. If additional characterization is required, the positioner or controller may be charac terized. However, these approaches are less direct, since it is possible for device nonlinearity and dynamics to distort the compensation. 

From the above it can be inferred that for an accurate analysis of a system, particularly where the loads are of varying nature or have non-linear characteristics it is necessary to conduct a harmonic analysis. The above corrective measures will provide a reasonably stable network, operat-ing at high p.f. with the harmonics greatly suppressed. The improved actual line loading, eliminating the fifth harmonic component, which is compensated,... 

To decide on the best reactive control one should choose the most appropriate electrical line length from the load characteristics drawn already. Choose the one that can transmit the optimum power, and then compensate this to obtain the required line length. For the 400 kV, 50 Hz system considered, we can choose a radial line with an electrical line length of 200-250 km. The compensation is provided so that the P ,aj point, which lies far from the natural power transmission point Pq, shifts within a stable region, i.e. near the Pq region. Then from equation (24.8),... 

I Shunt reactors These are provided as shown in Figure 24.23 to compensate for the distributed lumped capacitances, C , on EHV networks and also to limit temporary overvoltages caused during a load rejection, followed by a ground fault or a phase fault within the prescribed steady-state voltage limits, as noted in Table 24.3. They ab.sorb reactive power to offset the charging power demand of EHV lines (Table 24.2, column 9). The selection of a reactor can be made on the basis of the duty it has to perform and the compensation required. Some of the different types of reactors and their characteristics are described in Chapter 27. 

What are the best guess maximum and minimum limits of the load current and are there any intermittent characteristics in its current demand such as those presented by motors, video monitors, pulsed loads, and so forth Always add 50 percent more to what is told to you since these estimates always turn out to be low. Also what are the maximum excursions in supply voltage that the designer feels that the circuit can withstand. This dictates the design approaches of the cross-regulation of the outputs, and feedback compensation in order to provide the needs of the loads. 

The control-to-output characteristic curves for a current-mode controlled flyback-mode converter, even though it is operating in variable frequency, are of a single-pole nature. So a single pole-zero method of compensation should be used. The placement of the filter pole, ESR zero, and dc gain are... 

The form of compensation is the 2-pole-2-zero method of compensation. This is to compensate for the effect of the double pole caused by the output filter inductor and capacitor. One starts by determining the control-to-output characteristic of the open-loop system. 

The current-mode controlled forward converter has one additional consideration there is a double pole at one-half the operating switching frequency. The compensation bandwidth normally does not go this high, but it may cause problems if the closed-loop gain is not sufficiently low enough to attenuate its effects. Its influence on the control-to-output characteristic can be seen in Figure B-14. 

The schematic and Bode plot for the single-pole method of compensation are given in Figure B-16. At dc it exhibits the full open-loop gain of the op amp, and its gain drops at -20dB/decade from dc. It also has a constant -270 degree phase shift. Any phase shift contributed by the control-to-output characteristic... 

A compensator, or controller, placed in the forward path of a control system will modify the shape of the loci if it contains additional poles and zeros. Characteristics of conventional compensators are given in Table 5.2. 

Figure 6.39 shows, for both lead compensator designs, the closed-loop frequency response characteristics for the system. 

The control problem is to design a compensator D z), which, when cascaded with G z), provides a characteristic equation... 

A calibration facility must produce the desired velocity range for the meter to be calibrated. The air temperature should be kept constant over the test to ensure constant density. For thermal anemometers, velocity calibration only is not sufficient. They should also be checked for temperature compensation. In the case of omnidirectional probes, sensitivity to flow direction should be tested. In the case of low-speed (thermal) anemometers, their self-convection error should be measured, and, for instruments measuring flow fluctuation (turbulence), dynamic characteristics testing should be carried out as well. ... 

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