TM 9-4910-663-12
(c) Determine the speed of the driven generator by using the
following formula:
For example:
Have the drive pulley mounted on the low speed shaft of the varidrive.
When the diameter of the driven generator pulley is 5 inches, proceed
as follows:
1. Set TACHOMETER RPM SELECT switch (S36, fig 2-1) to DIRECT
DRIVE position.
2. Set the speed of the drive motor to 3000 revolutions per
minute onthe 0-5100 scale.
4. Set TACHOMETER RPM SELECT switch (S36, fig 2-1) to the
CAL PULLEY position.
5. Adjust TACHOMETER RPM meter (M1, fig 2-1) to read 2400
revolutions per minute on the 0-5100 scale, using TACHOMETER RPM
PULLEY CALIBRATION control (R35, fig 2-1). Any variation in the speed
of the driven generator will now be indicated directly on TACHOMETER
(d) Start the test stand (para 2-5a(5)) and adjust the speed
of the drive motor using SPEED CONTROL (fig 2-4) to some cardinal
point on the indicator scale, depending upon which output shaft is
being used.
(e) Turn TACHOMETER RPM SELECT switch (S36, fig 2-1) to the
CAL PULLEY position.
(f) Rotate TACHOMETER RPM PULLEY CALIBRATION control (R35, fig
2-1) until TACHOMETER RPM meter (M1,
fig 2-1) shows the speed deter-
mined in (c) above. This speed may be set on either scale. Stop the
varidrive.
Polarity Reversing Switch.
c.
(1) REVERSING switch (S7, fig 2-2) is used to establish the
grounding for the specific system undergoing test. The generating
system may be either negative ground or positive ground.
2-30