60 Hz\), model MEP-806A, NSN 6115-01-274-7390.

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MI L-DTL-53133/ 9C

operating conditions within 2 seconds. The maximum transient frequency change below the

new steady-state frequency shall be not more than 4 percent of rated frequency.

3.12 Frequency adjustment. By means of the frequency adjust device, it shall be

possible to adjust the frequency (when the set is operating at any constant load) as follows:

Between 58 and 62 but not above 65 Hz for the 60 Hz operating condition.

Between 48 and 52 but not below 45 Hz for the 50 Hz operating condition.

I t shall not be possible to adjust the frequency for operation within the 48 to 52 Hz range

when the frequency selector switch is in the 60 Hz position; and it shall not be possible to

adjust for operation in the 58 to 62 Hz range when the frequency selector switch is in the

50 Hz position. Further, it shall not be possible to adjust frequency to a value which will

actuate the overspeed protective device.

3.13 Voltage waveform. The deviation factor for the line-to-line and line-to-neutral

voltage waveform for each voltage connection shall be not more than 5 percent, nor shall

any single voltage harmonic be more than 2 percent. I n addition, there shall be no evident

discontinuities, spikes, or notches in the waveform when viewed on an oscilloscope having a

bandwidth of DC to 1.5 MHz and usable viewing screen of 8 x 10 cm. The oscilloscope gain

shall be adjusted such that one cycle of voltage wave covers approximately the entire

viewing screen.

3.14 Voltage unbalance. With the set operating at rated voltage and frequency and no

load, the maximum difference between line-to-line voltage shall be not more than 5 percent

of rated voltage for the 240/ 416-volt connection under the condition of a single phase, line-

t o-line unity pf-load of 25 percent rated current and no other load on the generator.

3.15 Phase balance voltage. The maximum difference in the three line-to-neutral

voltage shall be not more than 1 percent of the rated line-to-neutral voltage. The maximum

difference between the voltage of the 120-volt windings of any phase shall be not more

than 1 volt.

3.16 Voltage modulation. The voltage modulation of the output voltage for any load up

to and including rated load shall not exceed 1 percent. This requirement shall apply to all

line-to-line and line-to-neutral voltages.

3.17 Voltage regulation. The voltage regulation from no load to rated load and from

rated load to no load shall be not more than 1 percent of the rated voltage for all voltage

connections throughout the voltage ranges specified in 3.22.