MIL-M-23167B(SHIPS)
4.3.3 Zero adjustment. The range of zero adjustment above and below the center of the zero point shall be determined. Record shall be made as to whether or not the zero-adjuster may be rotated through
360 degrees without damage to the meter in addition to whether the zero-adjuster is designed for 360-de- gree rotation and is capable of withstanding a torque of 10 ounce-inches without damage to the meter.
4.3.4 Initial accuracy. Frequency meters shall be conditioned in the test circuit until thermal sta- bility is attained. The meter shall be energized at the center-scale value. Reading shall be taken and compared to the reading of the laboratory standard instrument. The test shall be made with the meter at a temperature of 45° ± 2°C.
4.3.5 Burden. The burden shall be measured at center-scale deflection and recorded in terms of volt- amperes to determine conformance with 3.18.
4.3.6 Inclination. Frequency meters shall be mounted in the inclined positions as follows and check for accuracy made at each position as specified hereinafter:
(a) 60 degrees forward of normal. (b) 60 degrees backward of normal. (c) 60 degrees to right of normal. (d) 60 degrees to left of normal.
4.3.7 Voltage range. Frequency meters shall be checked for accuracy at voltages specified in table IV, as applicable.
Table IV - Applied voltages at which meters are to be tested.
Voltage rating of meter |
Type designations |
Test voltage |
|
120 120 |
MR38W41AFH MR49W41AFH |
114 114 |
126 126 |
450 450 |
MR38W42AFH MR49W42AFH |
428 428 |
472 472 |
208 208 |
MR38W43AFH MR49W43AFH |
199 199 |
218 218 |
220 220 |
MR38W44AFH MR49W44AFH |
209 209 |
231 231 |
440 440 |
MR38W45AFH MR49W45AFH |
418 418 |
462 462 |
# 4.3.8 On-off cycling. Meters shall be subjected to a test of 2000 cycles of application and removal of rated voltage. The repetition rate of these cycles shall be sufficiently low so that the meter indicator momentarily comes to rest upon both application and removal of voltage. Lower repetition rates may be used in those cases where this test may cause excessive heating of the meter movement or scale expansion circuit. Change in indication as a result of this test shall be determined (see 3.8).
4.3.9 Overvoltage. Meters shall be subjected to 135 percent rated voltage for 15 minutes. Change in indication as a result of this test shall be determined (see 3.9).
4.3.10 External field influence. Frequency meters shall be placed at the center of a four turn coil 50 centimeters in diameter, carrying a current of 50 amperes of the same kind and frequency as that which actu- ates the meter mechanism and which produces a field of approximately 5 oersteds at the center of the coil. Readings shall be taken with the meter at various positions in the center of the field (see table I).
Note. - It is the intent to specify a test coil which will produce a uniform field of approximately 5 oersteds through the case of the meter. Therefore, coils, of other sizes may be used if an equivalent magnetic field is produced.
4.3.11 Temperature range. Frequency meters shall be maintained at each extreme temperature (0° and
65° C) for a sufficient time to attain thermal stability (approximately 2 hours). At the end of this period, readings shall be taken at each temperature. The effect of temperature shall not exceed the values specified (see 3.11).
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