Analysis and design of stator terminals reversal connection detector for Synchro-to-Digital converter
In this paper, a stator terminals reversal connection detector is presented for Synchro-to-Digital Converter (SDC). This is useful for identifying inadvertent reversal connection of synchro output signals to SDC. Synchro is a positional sensor excited by a sinusoidal signal and gives three electrical signals. The zero crossing outputs of synchro and a clock based on synchro excitation signal are generated. Then the phase relationship between excitation and synchro output signals is analyzed for possible stator terminal reversal connections between synchro and SDC. This method uses simple electronic components such as operational amplifiers, monoshots and flip flops. The analysis, implementation and experimental results are presented.
The Application of Synchro Transmitter in the Material Distribution Angle Control of a Blast Furnace
A material charging system is a critical process in a blast furnace. Raw materials are transported from the stock house to the top of furnace and distributed into the furnace. To put defined amounts of materials into the preset position, the control and detection of angular positions of flow control valves and the distributing chute on the top of the furnace is crucial. A synchro transmitter, used in combination with a synchro indicator, provides remote indication and control of the opening of valves, gates, dampers, and mobile equipment. In the proposed system, the synchro transmitter outputs a three-phase signal. The signal is finally transformed into a digital angular signal. By appropriate PLC control codes, the signal is a mapping of real mechanical angles or traveling length for operation and control. As a real application in a blast furnace, it is proved a robust, environment insensitive and stable solution of angle measurement and process control.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.