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1 Abstract Â— This report discusses the processes used to incorporate a custom control bus for the High Flux Solar Simulator using data acquisition devices. The wiring configuration for controlling the simulator is described in detail providing clear schematics and images. The LabVIEW program wiring diagram and front panel is explained to understand the control features to run the experiment. The success of operating the simulator with these control features are then discussed and acknowledged. I. INTRODUCTION The use of solar thermal energy has become widely used today, and can be used as a clean alternative to other energy resources. In order to improv e the effectiveness of this resource, careful analysis and research is performed using models that replicate the suns light. These models known as solar simulators reproduce the spectral distribution of natural sunlight with high accuracy (Kusuhara pp. 9-14). Conventional solar simulators typically use xenon short arc lamps, which provide light in the infrared region (800 to 1,000 nm). In order to test the performance of this energy resource, multiple levels of light intensity are emitted from the simulator. A controller is used to perform this task by adjusting the level of curren t supplied to each lamp. These controllers typically require manual operation, which can lead to interruptions or loss of data during experimental operations. When operating these experimental models it can be useful to incorporate data acquisition devices to record and analyze the results of a desired experiment. The experiments performed with this simulator will require data to be recorded over long periods of time. The main advantage of data acquisition devices is that it can record this data for long durations. This report analyzes methods used to implement and operate data acquisition devices on a solar simulator. II. APPARATUS The experimental set up consists of seven OSRAM XBO 6000 W/HSLA OFR high flux Xenon short arc lamps delivering radiative heat fluxes of 7000 kW/m2 ("Osram"). Each lamb is powered by seven Ernemann XE3-175 rectifiers (Â“ErnemannÂ”). Each of the rectifiers are connected to a custom made control bus to allow the lamps to be controlled remotely using data acquisition devices. Three data acquisition devices are used to record the data. The NI 9485 8-Channel Relay (Â“NIÂ”) is used as a solid state relay to turn the lamps on and off, providing 750 mA/channel. This device is labeled as DAQ switch in the block diagram. The NI 9213 16-Channel Thermocouple Input Module (Â“NIÂ”) is used to record the amperage of each lamb as well as the eight thermocouples used in the ther mal storage experiment. This DAQ reads voltages in a range of + 78.125 mV, and is labeled as DAQ amp reading in the bl ock diagram. The NI 9264 16Channel Analog Output Module (Â“NIÂ”) outputs the desired amperage required for each lamp based on the value specified in the block diagram. The device outputs voltages in the range of + 10V and is labeled DAQ amp output in the block diagram. A screen shot of the actual VI can be found in the Appendix. The wiring diagram and image shown in figures 1 and 2 below displays a control bus designed to control one lamp. In Figure 1 the connection to the DAQ is connected in parallel with a manual switch and each rectifier. When the switch is turned on the connection to the data acquisition device will be terminated and the lamps can only be manually operated. The wiring diagram is also orientated so that the manual switch always overrides the solid state relay. The connection shown on the bottom of Figure 2 connects the output data acquisition device directly to the rectifiers to allow the light intensity to be controlled when operating the experiment. The schematic in Figure 3 shows how the actual amperage is measured for each lamp. A shunt is incorporated into the back of each lamp where the current is sent to the data acquisition device to be recorded. Using Data Acquisition Controls on the High Flux Solar Simulator (November 2011) Nicholas Alcantara, University of Florida, Renewable Energy Engineering Laboratory Manual Switch Connection to Rectifier Connection to NI 9485 Channel Relay DAQ On/Off Control Figure 1 A schematic of the connections made to control when the lamp is on or off. Lamp Amperage Control Connection to NI 9264 Analog Output DAQ Connection to Rectifier Figure 2 A schematic of the connections made to control the amperage of the lamp.
2 Connection to Rectifier (Amperage Control) Connection to Rectifier (On/Off Switch) Manual Switch Connection to Channel Relay DAQ Connection to Analog Output DAQ Figure 4 displays the actual control bus incorporated into the simulator. The inside view is directly related to the schematics shown in Figures 1 and 2. The co mponents are stored inside a black rectangular box which can be screwed shut to ensure the wiring remains intact. The connection for the amperage control (shown in green) and the connection to turn the lamps on and off (the metallic connector) can easily be unplugged if desired, allowing the control bus to be portable. The diagram in Figure 5 shows the layout for the lamp controls. The NI 9485 channel Relay and the NI 9264 analog output directly connect to seven control buses. The control buses are then connected to the seven rectifiers which provide power to each lamp with the desired amperage. The NI 9213 thermocouple input is directly connected to the seven lamps to read the actual amperage. A common ground is used for each channel on the DAQ to complete the circuit as shown. III. TECHNICAL APPROACH In order to operate the control bus remotely a LabVIEW program is implemented. The block diagram was used to send and receive signals using the data acquisition devices. The block diagram controls three m echanisms. Each lamp can be switched on and off, a specified voltage can be powered and variably adjusted to provide a corresponding amperage, and the actual amperage can be recorded across a shunt attached to each lamp. The block diagram in the appendix uses many of the tools LabVIEW provides to obtain the readings. The Boolean controllers are in green, the variable controllers are in orange, and the indicators are shown in blue. In order to simplify the calculation to adjust the outputted values all seven wires are formed into an array. This is shown with seven wires entering the array builder to output on e stream. To record the time during the experiment a time st ep is created and incorporated into the data array. A Boolean control is wired to seven different wire outputs, which allows each individual lamp to be turned on and off when desired. These outputs leave the data acquisition device, labeled as DAQ switch on the block diagram. The switch is shown in the front panel at the center of each lamp control. A master control is also used to turn all lamps on at the same time. This is shown at the top of the front panel. A safety control is added to ensure the lamps automatically turn off when the program is stopped. Green LED indicators are wired to each switch to show which lamp is currently on. Once the lamps are turned on, the amperage of each lamp can be adjusted using the control meter shown as the left bar for each lamp in the front panel. Each lamp has an indicator below the meter which displays the estimated amperage input with an up and down arrow that allows it to be adjusted. The allowable amperage input ranges from 140A to 170A. Amperage values outside of this range may damage the bulbs; therefore a safety m echanism is implemented that prevents the indicator from imputing values above 170A and below 140A. This is shown in the block diagram as a case statement allowing the array titled Â“Estimated Amps ArrayÂ” to pass through if the values are in the desired range. Since the data acquisition device only outputs voltages, a relation is made to match the voltages to the corresponding amperage using the equation below: Where I is the current in amps and V is the voltage in volts. The values were recorded in a previous trial. Shown in the block diagram the array enters a formula, to adjust the value outputted. Another safety mechanism is added to output zero amps when the program is terminated. To read and record the actual am perage the voltage read from the shunt is sent to an input data acquisition device labeled as DAQ amp reading on the block diagram. The voltage is then Lamp Reading Connection to NI 9213 Thermocouple Input DAQ Shunt Figure 3 A schematic of the connections made to read the actual amperage of the lamp. Lamp Control Bus 1 Control Bus 2 Control Bus 3 Rectifier 1 Rectifier 2 Rectifier 3 NI 9264 DAQ NI 9485 DAQ NI 9213 DAQ Lamp 1 Lamp 2 Lamp 3 Figure 4 Image of the control bus with inner view on the right and outer view on the left. Figure 5 Layout of the connections for the DAQ devices and control buses for three of the seven lamps.
3 converted to an amperage based on previous trials and is shown below Where I is the current in amps and V is the voltage in volts. The wire on the block diagram from the DAQ enters formula 2 to adjust the imputed values An indicator for each lamp displaying the actual amperage as well as a meter showing the level is shown to the right of the amperage output. It should be observed that the reading will not be the same as the control amperage since it is estimated. In order to store the data a write to spreadsheet VI is added to the block diagram. An array is created inside the block diagram with a shift register to allow the data to be continuously recorded and stored in a text file. The data for each temperature as well as the actual amperage is incorporated into a 2D array. Prior to running the experiment the file path must be specified in the front panel. This is shown to the write of the block diagram where the array is built and sub arrays are added. The write to spreadsheet VI can be found in the appendix. An additional input device was incorporated into the LabVIEW program to successfully measure data during the thermal storage experiment. The experiment required eight thermal couple reading to be recorded using the data acquisition devices. Eight thermal couple indicators are located on the block diagram that output the actual temperature recorded, where the samples are read at 1 to 2 samples per second. A graph indicating all eight temperature values vs. time is displayed above the indicators on the front panel to show the temperature growth while the lamps are turned on. A safety feature is added with a green LED indicator that turns on when th e temperature reaches 1150 C. IV. CONCLUSION After the wiring configurat ion for each lamp and the LabVIEW program was complete the control system was successfully used in multiple experiments including the thermal storage experiment. The configuration designed in this report allows data recorded in any experiment to be easily recorded and analyzed for further research. The addition of this control system has become highly useful and reliable in the solar simulator laboratory. V. REFERENCES  Kusuhara, Masaki "Solar Simulator." Wacom Co., Ltd. (1985): pp. 914. Web. 23 Feb. 2012. .  "Ernemann Power Supplies for Xenon Arc Lamps." Ernemann CineTec N.p., n.d. Web. 23 Feb 2012. .  "Operating Instructions NI 9485." NI N.p., 2007. Web. 23 Feb 2012.  "Operating Instructions NI 9213." NI N.p., 2009. Web. 23 Feb 2012.  "Operating Instructions NI 9264." NI N.p., 2009. Web. 23 Feb 2012.
4 VI. APPENDIX Block diagram
5 FRONT PANEL LAMP CONTROL VI Lamp Control amps.vi write_to_spreadsheet_file+headers-1.vi