TM-9-2920-257-30&P Maintenance and Parts Manual for 200 Amp M113 Generator Download
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TM 9-2920-257-30&P APPENDIX E TEST STAND PROCEDURES E-1. GENERAL After repair of the generator it must be bench tested to verify correct operation. Follow the procedures below to calibrate test stand tachometer, set base settings for the test stands, and then perform tests on the 200 ampere generator/regulator and generator. E-2. CALIBRATION Military vehicle generators are equipped with various size pulleys, such as 3-, 3 1/2-, and 4-inch diameter. The 500-ampere test stand has a 4-inch pulley. Since the test stand tachometer reads drive head speed, the tachometer must be calibrated when a generator has a pulley larger or smaller than 4 inches. To calibrate the speed of the generator use fomula below. Formula: a = Test speed of test generator (normally lowest rated output speed as indicated by specifications). 4 = Diameter of drive pulley on test stand. b = Value of a x 4. c = Diameter of pulley on generator to be tested. e = Value of b divided by c (this value will indicate the speed of the driven pulley when the test stand speed (a) is at selected speed). aX4= b =e c Example: To test a generator with a 3-inch pulley, determine lowest rated speed of generator. If rated RPM for a generator is 2,000 RPM to 8,000 RPM, select 2,000 RPM as test speed. Increase test stand speed to 2,000 RPM with vari-drive speed control. Turn the calibrate pulley control to calibrate position. E-1