MIL-DTL-17060G(SH)
6.6.5 Efficiency. The efficiency of a machine is the ratio of the power output to the total power input. It is
expressed as a percentage.
6.6.6 Electromagnetic interference. Electric and magnetic fields that interfere with the proper operation of
electrical equipment.
6.6.7 Enclosures. The following definitions apply to enclosures:
6.6.7.1 Air-over. Motors with enclosures designated with the suffix air-over AO, are intended for exterior
cooling by a ventilating means external to the motor/
6.6.7.2 Submersible. Submersible motors are classified by their maximum rated submergence depth.
Submersible motors must operate in accordance with specification requirements while submerged and in air as
indicated in the duty cycle.
6.6.8 Front (of motor). The front or opposite drive end of a motor is the end opposite the coupling.
6.6.9 Full-load torque. The full-load torque of a motor is the torque necessary to produce its rated hp at full-
load speed.
6.6.10 Integral hp motor. An integral hp motor (see Appendix B) is one built in a frame size 182 or larger as
shown in table B of figures 1 through 4 and as shown in the frame size table for AC motors of MIL-P-17840 and
MIL-F-18953.
6.6.11 Inverter duty insulation system. An insulation system that can withstand the detrimental affect of
voltage pulses created by variable speed drives that use pulse width modulation techniques.
6.6.12 Locked-rotor current. The locked-rotor current of a motor is the steady-state current taken from the line
with the rotor locked and with rated voltage and frequency applied to the motor.
6.6.13 Locked-rotor torque. The locked-rotor torque of a motor is the minimum torque which it will develop at
rest for all angular positions of the rotor, with rated voltage applied at rated frequency.
6.6.14 Low noise surface ship application. An application where a specific structureborne noise limit is
applicable to the motor. Most surface ship motors do not have a specific structureborne noise requirement and
therefore are not classified as low noise surface ship motors.
6.6.15 Partial discharge. Electric discharge that only partially bridges the insulation between conductors.
Note: It may occur inside the insulation or adjacent to a conductor.
6.6.16 Partial discharge inception voltage (PDIV). Lowest voltage at which partial discharges are initiated in a
motor when the voltage applied to the motor is gradually increased from a lower value at which no such discharges
are observed. Note: With impulse voltages, the PDIV is defined as the peak to peak voltage.
6.6.17 Permanent magnet motor. A permanent magnet motor is a synchronous machine that uses permanent
magnets attached to the rotor core for field excitation.
6.6.18 Power factor. The power factor of an AC motor is the ratio of the kilowatt input to the kilovolt ampere
input and is usually expressed as a percentage.
6.6.19 Pull-in torque. The pull-in torque of a synchronous motor is the maximum constant torque under which
the motor will pull its connected inertia load into synchronism, at rated voltage and frequency, when its fixed
excitation is applied.
6.6.20 Pull-out torque. The pull-out torque of a synchronous motor is the maximum sustained torque which the
motor will develop at synchronous speed with rated voltage applied at rated frequency and with normal excitation.
6.6.21 Pull-up torque. The pull-up torque of an AC motor is the minimum torque developed by the motor
during the period of acceleration from rest to the speed at which breakdown torque occurs. For motors which do not
have a definite breakdown torque, the pull-up torque is the minimum torque developed up to rated speed.
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