Guardian Technologies 4760, 4456, 4390, 4389, 4759, 4758 manual Utility Voltage Dropout Engine Cranking

SECTION 4.2

OPERATIONAL ANALYSIS

PART 4

DC CONTROL

UTILITY VOLTAGE DROPOUT AND

ENGINE CRANKING

After fifteen (15) seconds and when the circuit board’s 15-second timer has timed out, if "Utility" voltage is still below 60 percent of nominal, circuit board action will energize the circuit board’s crank and run relays (K1 and K2) simultaneously.

The crank relay (K1) will remain energized for about 15 seconds on the first crank cycle. The relay will then de-energize for 7 seconds and will again energize. This time it will remain energized for 7 seconds. Thus, the engine will crank cyclically for 7 second crank-rest cycles. This cyclic cranking will continue until either the engine starts or until about ninety (90) seconds of crank-rest cycles have been used up.

When the crank relay (K1) is energized, circuit board action delivers 12 volts DC to a starter contactor relay (SCR), via Wire 56. When the SCR energizes, its contacts close and battery power is delivered to a starter contactor (SC). When the SC energizes, its contacts close and battery power is delivered to the starter motor (SM).The engine cranks.

When the circuit board’s run relay (K2) energizes, 12 volts DC is delivered to a fuel solenoid (FS), via Wire 14. The fuel solenoid (FS) energizes open and fuel is available to

the engine. Wire 14 also energizes the

hourmeter for operation (if so equipped) .Figure 3. Circuit Condition - Engine Cranking Wire 14 energizes the battery charge relay

(BCR), which will allow the BCR to power the battery charger.

As the engine cranks, magnets on the engine flywheel induce a high voltage into the engine ignition modules (IM1/IM2). A spark is produced that jumps the spark plug (SP1/SP2) gap.

During cranking, Wire 4 supplies 2-3 VDC (8- 9 VDC isolated) to the rotor for field flash.

With ignition and fuel flow available the engine can start.

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