Manual 82006 Digital Reference Unit
Woodward 1
Chapter 1.
General Information
Introduction
This manual provides description, installation, and maintenance information for
the Woodward Digital Reference Unit with three set points.
Digital Reference Units
Digital Reference Units use a precise linear ramp to provide a 0 to 8 volt
reference signal to the attached control. The reference unit can be used with a
speed or load control or a Process and Import/Export control. The reference unit
has two separate ramps which are switch selectable to control the 0–8 volt
reference signal.
The high, low, and intermediate points on the ramp are selectable on the
reference unit. The same set points are used by both ramps. One of the ramps is
always engaged so any movement of the output is at the speed of the engaged
ramp.
Options
Digital Reference units are available for use with a low voltage power source (10
to 45 Vdc) or a high-voltage power source (90 to 150 Vdc or 88 to 132 Vac at 45
to 440 Hz.)
The three-relay option may be used to provide indication of when the output is at
low limit, set point, or high limit, or to cause automatic switching functions within
the same system.
Part Number Power Supply Relay Indication
8272-682 10–45 Vdc No
8272-683 10–45 Vdc Yes
8272-684 90–150 Vdc or No
88–132 Vac 45–440 Hz
8272-685 90–150 Vdc or Yes
88–132 Vac 45–440 Hz
Applications
Digital Reference Units are used in place of MOPs (Motor Operated
Potentiometers), but provide more precise and more dependable control
functions. The Digital Reference Unit set points are easier to adjust than those
on a MOP, and the adjustable ramp time is generally not available with a MOP.
Installation of the maintenance-free Digital Reference Unit is less restrictive than
is installation of a MOP.
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