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Show 7. Hook the leads from sensor into the junction box at the base of the tower. ( Black wire comes from wiper; white is +, green is -.) Make notes on which wires from the sensors are hooked to which wires on the cable. When hooking up the recorder at the base area, be sure to follow the polarity on the recorder ( i. e. hook + to + and - to - ) . See block diagram ( Figure 19). 8. Hook the power supply- calibration module to the leads going up the mountain and to the left channel of the recorder. To be sure which wire is the wiper lead, check all three wires, two at a time with the ohmmeter while the vane is in the circuit and free to move. When two wires are found that give no meter movement, the third wire is the wiper lead. When either of the two leads being checked is the wiper lead, the variation in resistance caused by the movement of the vane will cause a slight movement on the ohmmeter. 9- Mount the anemometer on its base, secure with set screws, and run the leads from the anemometer to the junction box at the tower base. ( The leads from both anemometer and vane should be securely taped to the pipe brackets and tower.) Observe polarity and note color codes as for vane. Consult Figures 18 and 19 for correct connection scheme. Using the Ohmmeter to Check Wind Speed and Direction Cable ( Line check for continuity and shorts) 1. Study the Manual that comes with the volt- ohmmeter and learn how to zero the meter correctly and how to read the various scales. 2. Set the meter on 300 volts A. C. and check the line to be sure there is no voltage on the line. ( If there is a slight voltage, shift to a lower scale to determine how great it is. The source of the current must be found and eliminated before continuing the line check.) 3. Set the meter to RX10 or low enough to read less than 1000 ohms ( ft). 4. Station a man with a 2- way radio at the top of the mountain and another at the base area with another radio and an ohmmeter. 69 |