Control slip recovery systems

But where accurate speed control is the process requirement, static controllers, termed slip recovery systems (Section 6.16.3) are recommended, which in addition to exercising extremely accurate speed control, also conserve slip losses. Static drives are discussed in Chapter 6. Below we will describe a procedure to determine the value of resistance, its steps and switching and control schemes for these steps for a rotor resistance starter. 

Slip-recovery system (to control wound motors) 6/140... 

The inverter may be a current source inverter, rather than a voltage source inverter (.Section 6.9.4) since it will be the rotor current that is required to be vtiried (equation (1.7)) to control the speed of a wound rotor motor, and this can be independently varied through the control of the rotor current. The speed and torque of the motor can be smoothly and steplessly controlled by this method, without any power loss. Figures 6.47 and 6.48 illustrate a typical slip recovery system and its control scheme, respectively. 

Figure 6.47 Slip-ring motor control showing slip recovery system...

This is based on a sample fast loop with a sample take-off probe in the main process line, and a retnm to either a pnmp-snction or ambient pressnre sample recovery system (Fignre 5.22). The fast loop provides a filtered slip-stream to the analyzer, along with flow control and monitoring (low-flow alarm), and freqnently some form of sample antograb facility for sample capture. The slipstream flow to the internal analyzer sample flow cell is relatively low volnme and allows for a very high degree of sample temperature control (typically... 

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