b. Direct-Driven Generator.
97. Operating
the Tachometer Indicator
(1) Obtain the rated speed (rpm) for the
general or to be tested from table 1,
Note. The key numbers shown below in parentheses
paragraph 95, or from manufacturer's
refer to figure 16 except where otherwise indicated.
literature or nameplate data on gen-
a. General. The tachometer indicator cir-
erator.
cuitry is so designed that the speed or rpm
(2) If the rated speed is below 3,000 rpm,
(revolutions per minute) of the generator or al-
mount the generator on the low speed
ternator being tested, whether direct-or-pulley-
driving head (5, fig. 7). When the
driven, is indicated. It consists of a tachometer
rated speed is above 3,300 rpm, mount
generaton (B, fig. 64), tachometer indicator
the generator on the high speed driv-
meter (3), several control switches (18 and 19)
ing head (4, fig. 7). Follow mounting
and a potentiometer (58) for calibrating the
procedures prescribed in paragraph
circuitry. To determine the speed or rpm of
94.
the generator being tested proceed with cali-
(3) Turn the tachometer indicator high-
brating procedures as follows :
low switch (18) to the "LOW" posi-
43
