• Adjustable Idle Current
• Precision Speed Control
• Inputs for Accessories
• Reverse Voltage Protection
• Single Element Speed Switch
• Speed Anticipation Circuit
• Overspeed LED Indication
INTRODUCTION
The ESD5200 Series speed control unit is an all electronic
device designed to control engine speed with fast and precise
response to transient load changes. This closed loop
control, when connected to a proportional electric actuator
and supplied with a magnetic speed sensor signal, will control
a wide variety of engines in an isochronous or droop
mode. It is designed for high reliability and built ruggedly to
withstand the engine environment.
Simplicity of installation and adjustment was foremost in the
design. Non interacting performance controls allow near optimum
response to be easily obtained.
Other features include; adjustable droop and idle operation,
inputs for accessories used in multi engine or special applications,
a single element speed switch, protection against
reverse battery voltage, transient voltages, accidental short
circuit of the actuator and fail safe design in the event of loss
of speed sensor signal or battery supply.
DESCRIPTION
Engine speed information for the speed control unit is usually
received from a magnetic speed sensor. Any other signal
generating device may be used provided the generated
frequency is proportional to engine speed and meets the
voltage input and frequency range specification. The speed
sensor is typically mounted in close proximity to an engine
driven ferrous gear, usually the engine ring gear. As the teeth
of the gear pass the magnetic sensor, a signal is generated
which is proportional to engine speed.
Signal strength must be within the range of the input ampli-
fier. An amplitude of 0.5 to 120 volts RMS is required to allow
the unit to function within its design specifications. The
speed signal is applied to Terminals C and D of the speed
control unit. Between these terminals there is an input impedance
of over 33,000 ohms. Terminal D is internally connected
to Terminal E, battery negative. Only one end of the
cable shield should be connected.
When a speed sensor signal is received by the controller,
the signal is amplified and shaped by an internal circuit to
provide an analog speed signal. If the speed sensor monitor
does not detect a speed sensor signal, the output circuit of
the speed control unit will turn off all current to the actuator.
A summing circuit receives the speed sensor signal along
with the speed adjust set point input. The speed range has
a ratio of 8:1 and is adjusted with an internal 25 turn potentiometer.
The output from the summing circuit is the input to
the dynamic control section of the speed control unit. The
dynamic control circuit, of which the gain and stability adjustments
are part, has a control function that will provide
isochronous and stable performance for most engine types
and fuel systems.
The speed control unit output circuit is influenced by the gain
and stability performance adjustments. The governor system
sensitivity is increased with clockwise rotation of the gain
adjustment. The gain adjustment has a range of 33:1. The
stability adjustment, when advanced clockwise, increases
the time rate of response of the governor system to match
the various time constants of a wide variety of engines. The
speed control unit is a P I D device, the “D”, derivative portion
is fixed but can be easily varied, when required (See
Instability section).
During engine cranking, the actuator becomes fully energized
and moves to the maximum fuel position. The actuator
will remain in that state during engine cranking and acceleration.
While the engine is at steady load, the actuator will
be energized with sufficient current to maintain the governor
speed set point.
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