DE-3000 IOI 7-17
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24.2 The OEM ENGINE CONTROL sequence must begin from an engine stopped con-
dition. When a DE has been configured for OEM ENGINE CONTROL and an auto
start is signaled by grounding the ‘R’ terminal on the terminal board, Lube turns
ON, the Crank/Multi-Start disconnect timer starts, and the ‘Delay before ON’
timers for the Start/Run Signal and the Auxiliary output begin counting down.
DER remains ON from the time the auto start signal is sent to the DE-3000 until
a manual stop or fault occurs. All class A setpoints are monitored and class B
and C timers begin once the auto start signal is received.
24.3 Once the engine speed has surpassed a specified RPM, the Lube will turn OFF.
This Pre Lube Disconnect must occur before the Pre Lube time expires. If it
does not, a PRELUBE FAULT will occur and all four outputs will turn OFF and
the sequence will terminate.
24.4 The engine speed must also reach a speed above the Crank/Multi-Start discon-
nect RPM before its corresponding timer expires. If it does not, an OVERCRANK
FAULT will be generated and all outputs will turn OFF. If the DE-3000 is set up
for Multi-Start, then a delay timer will begin counting down before another start
attempt is automatically triggered. Pressing any button on the display during
the time between start attempts will cancel Multi-Start, and the DE-3000 will
remain in a Stop/Fault mode until it is manually restarted.
24.5 The Auxiliary and Start/Run Signal turn ON once their corresponding ‘Delay be-
fore ON’ timers expire. The Auxiliary output will remain on for the entirety of the
DE’s run time, but the Start/Run Signal can be programmed to turn OFF after
1-5 seconds, or just remain ON during the DE’s run time.
24.6 When a manual stop or fault occurs, DER turns OFF and Lube turns ON. The
Auxiliary and Start/Run Signal (if still ON) remain ON after a stop or fault for
their respective ‘Hold after Stop’ times and then turn OFF. Lube turns OFF after
its programmed Post Lube time.
25.0 SELECTING A CONTROL STRATEGY
25.1 The control strategy best suited to a particular application varies widely. The fol-
lowing information is offered as a set of general guidelines and definitions. Each
application should be evaluated by qualified personnel familiar with the actual
operating conditions.
25.2 The DE-3000 controller can be programmed to regulate compressor throughput by
controlling both capacity and engine speed. In any particular application, it may be
desirable to control the total compressor throughput using only one of these.
25.3 The RPM control of the engine can be done using one of the analog control out-
puts of the DE-3000 as a 4-20mA current loop which can be connected directly
to an electronic governor. If a governor requiring a pneumatic setpoint (3-15psi)
is used then the 4-20mA output is connected to an appropriate I/P transducer.
25.4 The CAPACITY control output of the DE-3000 is available in two formats, to
drive the most common actuating systems. The first output format is an indus-
try-standard 4-20mA current loop used for continuously adjustable (sometimes
referred to as linear) control. The 4-20mA. output would typically be used to
interface to a pneumatically controlled bypass valve. A second set of capacity
control outputs is brought out of the controller in a digital format (discrete tran-
sistors). The digital or discrete outputs consist of two transistors which switch
on to ground and are designed to drive relay coils or pilot duty solenoid valves.
One switch is labeled DIGITAL OUT 1 and energizes to LOAD the compressor
the other is labeled DIGITAL OUT 2 and energizes to UNLOAD the compressor.
The typical application on reciprocating compressors would be to use the
4-20mA. CAPACITY output to connect to an appropriate I/P transducer which
then connects via tubing to the actuator input of a pneumatically controlled
external bypass valve.
On some screw compressors utilizing an internal stepless bypass, a spring-bi-
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