Guardian 4721, Repair Manual

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PART 4
CIRCUIT CONDITION- INITIAL UTILITY VOLTAGE DROPOUT
• Line-to-line “Utility” current is delivered to the sensing transformer. Transformer action reduces the line-to-line
voltage to approximately 14 volts AC. The reduced voltage is delivered to the control board as “Utility” sensing
voltage. If “Utility” source voltage drops below about 60 percent of rated voltage, control board action will turn
on a “15-second timer”.
• Voltage is unavailable from both power sources to load terminals T1/T2. Some timing loss may occur on the
control board’s 7-day exerciser clock.
Page 64
DC CONTROL
LIQUID COOLED
ENGINE UNITS
SECTION 4.2
OPERATIONAL ANALYSIS