MIL-DTL-3124E(SH)
4.6.15 Wave shape. The wave shape shall be taken by photographic means from oscilloscopes or by means of
digital data acquisiters. The test shall be made when the generator is operating at rated frequency, rated voltage, and
no load, as well as rated full-load unity power factor. The following tests shall be conducted with the generator
under control of the excitation-voltage regulation system.
4.6.15.1 Harmonic analysis. A harmonic analysis shall be made with the equipment operating at rated
frequency, rated voltage, and no load, as well as full-load unity power factor (purely resistive load). All harmonics
up to the 31st harmonic shall be measured.
4.6.15.2 Deviation factor. The deviation factor shall be determined with the equipment operating under the
conditions specified in 4.6.15.1.
4.6.16 Efficiency. When the efficiency of a generator is stated without specific reference to the load
conditions, rated load shall be understood. The efficiency shall correspond or be corrected to conditions of rated
voltage, current, frequency, and power factor, as may apply. The efficiency shall be determined for 50, 75, and 100
percent of rated continuous kilowatts at rated voltage, frequency, and power factor.
4.6.16.1 Detailed measurement of losses. For generators rated 30 kilowatts or less, it shall not be necessary to
segregate the several losses indicated herein. In such cases it shall be sufficient to measure the sum of those losses
which remain substantially constant at each load (bearing friction and windage, brush friction, brush contact, and
core losses), and separate these from each other and from those losses which vary with the load (armature and field
I2R losses and stray load losses), only as necessary to the proper computation of efficiency. For generators rated
more than 30 kilowatts, the several losses shall be measured in the manner specified herein.
4.6.16.2 I2R losses. The armature and field I2R losses shall be separately calculated as the product of the
square of the current at the load for which the loss is to be computed and the measured DC resistance of the circuit
corrected to 257 °F (125 °C).
4.6.16.3 Friction and windage losses. The generator shall be driven at rated speed by an independent motor or
prime mover, the output of which shall be determined when driving the generator not excited. The prime mover
output, when driving the generator, represents the friction and windage loss.
4.6.16.4 Core loss. Core loss shall be measured in accordance with IEEE 115.
4.6.16.5 Stray load losses. Stray load losses shall be measured in accordance with IEEE 115.
4.6.16.6 Miscellaneous losses. Miscellaneous losses shall be as specified in 4.6.16.6.1 and 4.6.16.6.2.
4.6.16.6.1 Blower supply losses. When a separately driven blower supplies air to a single generator, the power
required shall be charged against the generator. When one or more separately driven blowers supply air through a
single duct to two or more generators, the power required to drive the blower or blowers shall be charged in
proportion against each single generator.
4.6.16.6.2 Voltage regulator and excitation system losses. Power supplied to the voltage regulator and the
brushless excitation system shall be considered a loss in determining efficiency.
4.6.17 Weight. The weight of the generator shall be measured.
4.6.18 Automatic voltage regulator. One completely assembled generator and exciter shall be tested with the
intended voltage regulator. This test shall be conducted in accordance with MIL-R-2729.
4.6.19 High-impact shock test. The generator shall be tested with the prime mover and meet the requirements
of MIL-G-3087, MIL-G-21296, or MIL-G-22077, as applicable. The high-impact shock tests shall be in accordance
with MIL-S-901.
4.6.19.1 Design analysis. The "Procedure for Dynamic Shock, Analyses, Review and Acceptance" shall be
followed with regard to review and acceptance of dynamic design analysis. (A copy of this procedure may be
obtained from NAVSEA.) Identical procedures shall be followed with regard to static analyses. The reviewing
activity is the Supervisor of Shipbuilding, New York.
26
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business