MIL-DTL-17060G(SH)
3.6.12 Dielectric strength. Motors shall withstand dielectric test voltages specified in table XV (see 4.6.17).
TABLE XV. Dielectric test voltages.
Part
Test voltage
Minimum duration
Secondary windings of wound rotors:
1,000 plus twice normal induced voltage on
1 minute
Nonreversing
open circuit
Reversing, while running at
1,000 plus four times normal induced voltage on
1 minute
approximately normal speed by
open circuit
reversing the primary connections.
To be started with the field open
1.5 times the maximum r/min voltage which can
1 minute
circuited and sectionalized
occur between the terminals of any section but
in no case less than 2500 volts or 10 times the
rated excitation voltage per section, whichever is
the larger
All others:
Motors rated more than 600 volts
2,000 plus 2.25 times rated voltage.
1 minute
1,000 plus twice rated voltage or 1,200 plus 2.4
1 minute
Motors rated 600 volts or less
times rated voltage
1 second
3.6.13 Electrical balance. With balanced voltage applied, amperes in any phase at rated load shall not differ
from the arithmetic average of the maximum and minimum phase amperes by more than 10 percent for motors rated
1½ hp and under; by more than 7½ percent for motors rated 2 and 3 hp; and by more than 5 percent for motors over
3 hp (see 4.6.18).
3.6.13.1 For submarine applications. The maximum deviation of any phase current from the average of all
phase currents shall be not greater than 3 percent (see 4.6.18).
3.6.14 Efficiency. Efficiency requirements apply to design A, B, and B7 continuous duty motors, only. Design
3.6.14.1 Single speed motors. Single speed design A and B7 motors shall have a minimum full-load efficiency
as specified in table XVI. Single speed design B motors shall have full-load efficiencies reduced by not more than 1
percentage point from that specified in table XVI.
3.6.14.2 Multispeed motors. Multispeed design A and B7 motors shall have full-load efficiencies reduced by
not more than 3 percentage points from that specified in table XVI for the highest speed only. Multispeed design B
motors shall have full-load efficiencies reduced by not more than 4 percentage points from that specified in table
XVI for the highest speed only. Efficiencies for all other speeds need not be as specified in table XVI.
3.6.14.3 Motors with shaft seals. Motors with shaft seals shall meet the efficiency requirements of 3.6.14.1
through 3.6.14.5 either with or without seals.
3.6.14.4 VSD motors. Only VSD motors meeting the requirements of 3.5.2.8.2 have an efficiency requirement.
These VSD motors shall have a minimum efficiency at rated horsepower of not less than 2 percentage points below
the appropriate value of table XVI. The speed used in determining the appropriate value in table XVI is the base
speed. Rated horsepower is the horsepower output requirement at base speed (see 6.2).
3.6.14.5 Non-standard hp ratings. Design A, B, and B7 motors furnished in hp ratings other than those
specified in table XVI shall have full-load efficiencies as specified in 3.6.14.1 through 3.6.14.5 for the next lower hp
rating.
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