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will not restore power to the outlets until the mains voltage is less than 130 volts.
The reason for this is to prevent the power oscillating on and off in marginal
conditions.
LED Voltmeter: This three-color, 20-LED bar graph is an accurate, self-checking
AC voltmeter that continually measures the IT-1220's input voltage. The meter
reads from 90 to 128 volts in two-volt steps. The normal range voltages are
indicated in green, with moderate and extremely high or low voltages in yellow
and red respectively (see chart on the previous page). The voltmeter provides
three special flashing patterns to indicate abnormal power conditions:
1. If only the single LED located beneath the number 90 on the voltmeter flashes,
voltage at the IT-1220 input is below 90 volts. Power to the IT-1220 outlets will
remain on unless the incoming voltage falls below 80.
2. If all of the LEDs on the voltmeter flash, voltage at the input is between 130
and 140 volts.
Power to the IT-1220's outlets will remain on unless the incoming voltage
exceeds 140.
3. If none of the LEDs on the voltmeter are lit, and the Extreme Voltage LED
indicator is flashing continuously, then the IT-1220 has shut down power to its
switched outlets due to input voltage below 80 volts or above 140 volts.
The IT-1220's voltmeter has a basic accuracy of plus or minus two volts, and
extreme cold or heat may cause an additional one -volt of error. Please note that
the voltage reading is advisory only. The IT-1220 does not compensate for high
or low line voltage. If you frequently move your rack to different locations, derive
power from generators, use long extension cords, travel internationally, or are in
an area prone to brownouts, you may benefit from the use of one of Furman's AC
Line Voltage Regulators.
NOTE: Because the voltmeter reads the input voltage BEFORE the circuit
breaker on-off switch, its LEDs stay on whenever the /T- 1220 is plugged in, even
when the power switch is off. This feature allows you to check voltage before
powering up your equipment The LEDs are designed for continuous, ongoing
use. They consume little power, just a few cents worth a month, like a clock.
Ground Fault Interrupter (GFCI): The GFCI on the IT-1 220's front panel is a
special kind of circuit breaker that detects an imbalance in the current flowing in
the two hot legs. The "missing" current is presumed to be flowing through the
ground conductor (the round pin on an AC outlet).
Ground current often indicates a dangerous partial or full short circuit. If an
imbalance is detected, the GFCI trips and cuts off power not only to itself, but to
all the IT-1220's outlets. If this occurs, the button on the GFCI marked "R"
(Reset) will pop out. To restore operation, correct the fault and push the button
in. You may test the proper operation of the GFCI at any time by simulating a
ground fault by pushing the button marked "T" (Test). If the GFC1 is working
properly, this will cause the "R" button to pop out and cut off power. You can
restore operation after a test by pushing the "R" button in.
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