ARMY TM 9-6115-464-34
AIR FORCE TO 35C2-3-445-2
NAVY NAVFAC P-8-624-34
(c) The recording meter chart speed(s) shall be 12 inches per minute throughout the remainder
of this test. At each of the following load conditions (one step) operate the set for a minimum of 40
seconds (or the short-term stability period plus the allowable recovery time as specified in the
procurement document). During each load condition read and record all instrument readings except
thermal instrumentation (for three-phase sets it is not necessary to record line-to-line voltages).
Each load condition shall be applied to the generator set in one step at the end of the short-term
stability period for the previous load condition. The load conditions are:
1. Rated load
2. No load
3. Rated load
4. No load
5. Rated load
6. No load
7. Rated load
8. No load
9. 3/4 rated load
10. No load
11. 3/4 rated load
12. No load
13. 3/4 rated load
14. No load
15. 1/2 rated load
16. No load
17. 1/2 rated load
18. No load
19. 1/2 rated load
20. No load
21. 1/4 rated load
22. No load
23. 1/4 rated load
24. No load
25. 1/4 rated load
26. No load
27. Rated load
28. No load
29. Rated load
30. No load
31. Rated load
32. No load
(d) Repeat (a) through (c) for all voltage connection(s) and frequency(ies).
d. Results.
(1) Prepare a chart giving for each load change the momentary overshoot or undershoot and the
recovery time. For each constant load, give the maximum voltage variation.
(2) Referring to figure 4-1 begin by determining the observed (B) and steady-state (D) voltage
bandwidths.
(a) Mark numerically the stabilizations occurring after each load change, starting with the stabilization
obtained before the first load change.
(b) Determine the observed voltage bandwidth (B) by marking the maximum trace excursion and
minimum trace excursion in the stabilized portion. Draw two lines parallel to the axis of chart
movement, one each passing through these maximum and minimum trace excursions respectively.
(c) Draw a line (C) parallel to and equidistant from the edges of the observed voltage bandwidth.
Determined in (b) above.
(d) Using the rated voltage of the generator and given requirements of table 4-1, calculate the
steady-state voltage bandwidth (D). Draw this steady-state voltage bandwidth as two parallel lines,
parallel to and equidistant from the median (C) at the observed voltage bandwidth.
4-12
