VR-32 Regulator and CL-2AControl
3-2
DRIVER MECHANISM - Spring-drive
Two steel extension springs are arranged in a triangular con-
figuration to provide positive “spring-over-center” action to
move the switch contacts. The mechanism is adjusted for
smooth make and break contact action.
DRIVE MECHANISM - Direct-drive
The 770B and 660C tap changers employ drive mechanisms
based upon the same design principle, and many components
are interchangeable. The motor turns a geneva pinion three
complete revolutions per tap change. The motion of the geneva
pinion turns a six-tooth geneva gear, a main drive shaft, and a
scroll cam 180 degrees per tap change. Each 180-degree move-
ment of the scroll cam operates one of two roller plates and
moves the corresponding main movable contacts 40 degrees. The
combination of geneva gearing and scroll cam characteristics
results in a threestep, wipe/transfer/wipe contact action.
Attached to the main (geneva gear) drive shaft is a planetary
gear-type mechanical stop which prevents contact motion beyond
the maximum raise and lower position.
Figure 3-1
928D spring-drive tap changer.
Figure 3-3
770B direct-drive tap changer.
Figure 3-4
660C direct-drive tap changer.
Figure 3-2
170C spring-drive tap changer.
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