CONTROL PANEL (TYPE 2)
SYSTEMS OPERATION
AUTOMATIC START/STOP SYSTEM
Introduction
The automatic start/stop system is normally used for
standby operation. That is, without an operator. The
generator set must start, pick up the load, operate the
load, and stop after the load is removed. An automatic
transfer switch controls the transfer of load to and from
the generator set. When normal (commercial) power
has a failure, initiating contactor (I), part of the automatic
transfer switch, closes. This will begin the automatic
start sequence. When the engine starts, the control
panel instruments will show voltage and frequency. The
automatic transfer switch will transfer the load to the
generator set when voltage and frequency reach
approximately rated value. When normal power returns,
the automatic transfer switch will transfer the load back
to normal power. Initiating contactor (I) will open. This
will begin the automatic stop sequence. The generator
set will also stop automatically if the engine has a failure.
NOTE: There are two types of
automatic start/stop systems used
with
the
earlier
type
generator
mounted control panel. One uses a
mechanically driven speed switch
(USS and OSS) and an oil pressure
switch (OPS) that is the shape of a
cylinder. The other uses an electrical
speed switch (DSS) and an oil
pressure switch that is the shape of a
box.
Automatic Start
With engine control switch (ACS) in the AUTO
position, contacts 1, 2 and 6 are closed. When
commercial (normal) power has a failure, initiating
contactor (I) closes. This makes a complete circuit from
battery (BATT) to energize run relay (RR), magnetic
switch (MS). dual speed switch (DSS) (it so equipped)
and overcrank timer (OCT).
When run relay (RR) is energized, contacts (RR2)
open and contacts (RR1) close. (RR2) open prevents
current flow to rack solenoid (RS) through pressure
switch (PSW). (RR1) closed makes it possible to
energize oil pressure indicator (OPI).
When magnetic switch (MS) is energized. (MS)
contacts close and pinion solenoid (PS) is energized.
This causes (PS) contacts to close, starting motor (SMJ)
will crank the engine. (FPS) or (PSW) will close. This
energizes water temperature gauge (WTG) and oil
pressure gauge (OPG).
When overcrank timer (OCT) is energized. a timer
will start. After the engine cranks for approximately 30
seconds, the timer will top. (OCT) contacts will close.
Make reference to ENGINE DOES NOT START.
When dual speed switch (DSS) (if so equipped) is
energized, the magnetic pickup relays the engine rpm to
the switch. The dual speed switch has an underspeed
(USS) circuit and an overspeed (OSS) circuit.
Manual Start
The current flow for manual start is similar to
automatic start except engine control switch (ACS) is
turned to the MAN position. Contact (2) is open and
contact (3) is closed. It is not necessary for initiating
contactor (I) to close. Run relay (RR). magnetic switch
(MS) and overcrank timer (OCT) will energize as soon
as contact (3) is closed.
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