Emerson Keystone EPI2 63 - Machine Description; General; Principle of Operation; Electrical Operation

Installation, Operation and Maintenance Manual
MAN-10-04-100-0711-EN Rev. 0
October 2020
7
Machine Description
Section 2: Machine Description
Section 2: Machine Description
2.1 General
The Keystone EPI2 is an electric quarter-turn actuator suitable to operate a valve in a
90° maneuver.
2.2 Principle of Operation
The electric motor drives the input to an epicyclical gear train via a spur reduction.
The input member of the epicyclical gear train carries two compound planet gears which
meshes with one internally toothed gears: the xed annulus. The xed annulus gear has
external helical teeth meshing with a transversely xed worm gear. Since the annulus
cannot drive the worm gear this provides a xing point for the annulus, and since the
worm gear can drive the annulus, a means of manual operation is provided which needs
no declutch.
An end-of-travel-position detection device is operated via a position sensor directly linked
to the output shaft. The valve position is continuously monitored in electric mode by
means of a position sensor directly connected to the Keystone EPI2 output drive.
2.3 Electrical Operation
— Control command 'open': counter-clockwise or clockwise rotation
(selectable on the logic board) moves the valve to a completely or
partially open position.
— Control command 'closed' : clockwise or counter-clockwise rotation
(selectable on the logic board) moves the valve to a completely or
partially closed position.
— Control system details are shown in the specic wiring diagram.
NOTE
Handwheel rotation
In standard applications clockwise rotation of the handwheel moves the valve to
close position and counter-clockwise rotation moves the valve to open position.
Different operation are clearly indicated on the handwheel.