Couplings speed control

Coupling digital controls with networking technology permits information to be passed from level-to-level within a corporation at high rates of speed. This technology is capable of presenting the measured variable brom a flow transmitter installed in a plant in a remote location anywhere in the world to the company headquarters in less than a second. 

These couplings are adjustable and therefore can also facilitate speed control. 

Figure 8.9(b) illustrates a general scheme to achieve speed control through such couplings. These couplings, up to 90 kW, are easily available. 

Figure 8.9(b) A general scheme illustrating speed control by feedback control system using an eddy current coupling... 

There is special coverage of fluid couplings for soft starting and speed control, A comparison between static drives and variable-speed fluid couplings is inade. 

Variable speed control Speed change may be achieved by belts, pulleys, gear box sliding couplings, or a variable-speed motor. 

On the morning of January 22, 1972, a 44-car cut was being classified. One car, an empty hopper, was humped without incident but stopped approximately 400 m (1300 ft) short of its planned coupling point. Later, three tank cars containing propylene were humped as a unit and directed onto the same track as the empty hopper. The cars should have been slowed by the speed control system, but were not, probably because of greasy wheels. An overspeed alarm was given. The unit ran into the empty hopper at a speed of approximately 25 km/h (15 mph). 

Similarly, the uncertainties around the rate controlling step for the slurry reactor may also be dealt with through overdesign of the control system. In that case it may be prudent to provide a couple of control loops that could control the addition of reactant gas through some high-pressure jet spargers or provide a variable speed agitator. 

Figure 12 Experimental set-up of Taylor vortex photocatalytic reactor (Dutta and Ray, 2004) (1) motor, (2) speed controller, (3) gear coupling, (4) UV lamp, (5) sample collection point, (6) lamp holder, (7) outer cylinder, (8) catalyst-coated inner cylinder.

The moped looked pretty normal except for a couple of metal boxes— the fuel cell and a NiCad battery—mounted in the frame ahead of and underneath the rider. Kordesch converted the Austrian-made Puch (bought at Sears, Roebuck) in 1966, and he drove it on public roads during his years at Union Carbide. There were two 16-volt, 400-watt hydrazine-air alkaline fuel cells and a Ni-Cad battery. The batteries could be switched in parallel or series for speed control. The range was about 60 miles on 2 liters of a 64 percent aqueous hydrazine, with an easy top speed of 25 miles per hour. 

Battery-Electric Equipment. This is mechanically simpler in design than engine-driven equipment. Typically, the high-torque dc electric-drive motor is coupled directly to the drive axle through a constant-mesh drive train. An electronic silicon-controlled rectifier (SCR) speed-control device regulates the motor s revolutions per minute through operator foot control. Direction is reversed electrically with a delay interlock to avoid reversing motor direction while in motion. 

Sometimes the frame is mounted on a sub-frame together with the drive motor, and where necessary a back-drive system, to control the gearbox pinion shaft, which will in turn control the conveyor-to-bowl differential speed. The back-drive system will be described later, but for the present it suffices to say that it is essentially a braking motor or similar device coupled to the gearbox pinion shaft. The main motor is offset from the bowl and drives the bowl by means of a set of V-belts. The back-drive can also be offset, in which case it would be connected with a timing belt. The timing belt is to facilitate more accurate speed control. However the back-drive system can also be mounted direct in line with the pinion of the gearbox. 

With main drive and back-drive systems under control, it remains to control centrate quality. For this, a good centrate monitor is required, capable of assessing the level of suspended solids in the centrate. This has been difficult but there are a few reliable devices now available on the market [20]. The monitor is then coupled via a PID controller to the polymer pump speed control. 

Sodium pumps. Problems with the pumps resulting in unplanned energy losses occurred in 1981-1985, and were caused by unstable operation of the pump speed control stem. Impulses from the electric motors caused failures of the pump-motor couplings, and increased vibration and fatigue cracks in the pump shafts. The use of advanced shafts and couplings and changing to a steady mode of pump operation after attaining the preset reactor power level have eliminated any failures of the reactor coolant pumps since 1985. 

The BOR-60 pumps are driven by standard motors with stepless speed control. For the BN-350 pumps special squirrel-cage induction motors with two speeds (250 and 1000 rpm) are used. For the BN-600 pumps controllable synchronous motors are used coupled to synchronous-rectifier drivers with phase rotors. 

The SNPP TRACE model shown in Figure 12-2 represents two parallel Brayton loops directly coupled to a gas reactor, with a water coolant HRS loop dedicated to each Brayton. The TRACE model is built and edited with SNAP using four views. These include the primary hydraulic and instrumentation view shown in Figure 12-2 the HRS hydraulic view shown in Figure 12-12 the Brayton shaft and speed controller view in Figure 12-9 and the reactivity calculation and control view in Figure 12-7. 

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