A cradled-generator dynamometer employing feedback speed control
and constant-torque loading of a tested motor was constructed and tested.
The dynamometer assembly consisted of a cradled d-c shunt generator,
a drag-cup-type tachometer, and a spring-balance torque-measuring device.
Pictures of the dynamometer assembly with the tested motor and
shaft coupling removed may be found in figs. 1 & 2 on pages 24 &25 .
The dynamometer and all control equipment was designed to operate from
the standard power panels found in the M.I.T. measurements and machinery
laboratories. Where possible, the 345-volt, d-c regulated power supply
was used to reduce the errors in measurement that would arise from
normal voltage fluctuations.
Dynamometer speed was determined by a Strobotac, whereas speedcontrol
voltage was determined by a tachometer.
la. Cradled Generator
The construction of the cradled-generator dynamometer mounting
is shown in fig* 3, page 26. The d-c generator was an *Electric Motors