Woodward EM-80/EM-300 Actuator System

Introduction

This manual covers components of the EM-80/-300 Actuator System and does

not include operating instructions for the prime mover or the driven devices or

processes. For information about other Woodward products used in conjunction

with the EM-80/-300. please refer to the specific Woodward documentation

supplied with each product.

For specific operating information such as start-up, shutdown, and the prime

mover's response to signals from the Woodward control, refer to the prime mover

manufacturer's manual.

Description of Components

The EM-80/-300 system provides an all-electric actuation system for various

prime mover control applications.

The system is intended for use on large diesel, gas, and gasoline engines, and

on all types of turbines, to control the position of the engine fuel racks, turbine

fuel racks, turbine and turbocharger variable geometry, and to perform timing

control.

The EM Driver controls the EM-80/-300 Actuator position proportional to a

position demand signal received from a controlling device. The EM-80/-300

Actuator consists of a high-performance three-phase brushless ac motor that

drives a precision planetary gearbox.

EM-80/-300 System Description

The EM-80/-300 system consists of an actuator, a driver, an AC line filter

(required for marine TN/TT only), and interconnection cables.

The EM-80 and EM-300 are all-electric actuator systems that provide a nominal

40° of actuator output rotation. Each system consists of a three-phase brushless

ac motor which drives a high-precision planetary reduction gear box. A dedicated

driver controls the actuator position.

Actuator

The actuator is available in two versions, offering two work output levels, EM-80

and EM-300. Both versions use the same three-phase brushless AC motor.

The difference in output is achieved by the use of two different gearboxes. The

EM-80 uses a single-stage planetary 1:7 gear ratio, while the EM-300 uses a

two-stage planetary 1:20 gear ratio.

The motor–gearbox combination comes assembled on a mounting bracket with a

fixed hole pattern. Although the EM-300 is longer than the EM-80. both use the

same mounting hole pattern, allowing the actuators to be interchangeable.

The output flange provides an easy mounting surface for a variety of lever

configurations, and is equipped with a rugged pointer and scale for quick output

position reference while working on the prime mover. A breakaway extension and

two stop pins form a simple means of detecting whether the actuator has been

driven outside its operating boundaries.

Electrical connections are made in a standard, shielded, three-phase terminal

box mounted on the motor, and will accommodate standard cable. The resolver

cable has a 1 m (39”) flying lead that removes the connector from the high

vibration environment of the prime mover. The use of the specified resolver cable

and connector will help ensure correct connections to the driver.

The EM-80 and EM-300 actuators have different position-sensing systems. Both

systems use the same hollow shaft resolver, producing a sine and cosine wave

output with an overall accuracy of 12 arc-minutes. This resolver is mounted at the

rear of the motor and looks at the relative position of the motor shaft.

The EM-80 uses only the resolver since the 1:7 gear ratio within the gearbox

allows full stroke of the actuator output flange with less than one full revolution of

the motor shaft.

The EM-300 has a 1:20 gearbox ratio to achieve the required torque output.

Because of this, the motor shaft rotates more than one full revolution to achieve

full stroke. To ensure proper position indication over the full range, a 10-turn

potentiometer is added behind the resolver to supply a coarse position signal

from which the correct rotor revolution is deduced. The same resolver as used on

the EM-80 gives the accurate position within that revolution.