Section 2: Machine Description; General; Principle Of Operation; Electrical Operation - Emerson Keystone EPI2 63 Installation, Operation And Maintenance Manual

Installation, Operation and Maintenance Manual
MAN-10-04-100-0711-EN Rev. 0

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 fixed annulus. The fixed annulus gear has
external helical teeth meshing with a transversely fixed worm gear. Since the annulus
cannot drive the worm gear this provides a fixing 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

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.
Machine Description
— 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 specific wiring diagram.
Section 2: Machine Description
October 2020
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