A R - 1 2 2 0 A C L I N E V O L T A G E R E G U L A T O R
the equipment, see fi gure 1.
The AR-1220 has twelve 20A outlets on the back,
and two 15A outlets on the front. All are functionally
interchangeable. The outlets are regulated, spike
suppressed, and fi ltered against FIR with a 3 pole
fi lter, making the unit a full function power condition-
er. There are no controls except an on off breaker
switch. (The AR-1220J also has an output voltage
selector switch.)
Limitations: These Line Voltage Regul ators are for
use with AC voltage only. DC voltages should never
be applied to them. Also, they do not change or
regulate line frequency. The output frequency will
always be the same as the incoming line frequency.
MAXIMUM LOAD
The AR 1220 can handle loads totalling up to 20
amperes as long as the input voltage is equal to
or above 124 volts. For voltages below that level,
its capacity must be derated at approximately .10
amperes per volt. See fi gure 2. As a practical mat-
ter, therefore, to cope successfully with worst case
brownout condi-tions, you should plan your total
load so that it does not exceed 16.5 amps, or 1980
watts. Please note that this refers to the aggre-gate
power requirement of all equipment plugged into the
Voltage Regulator, not to each individual item.
EXTREME VOLTAGE PROTEC-
TION
The AR Series includes special circuitry to sense
over and un-der voltages and positively shut down
the output before possible damage is done. For the
AR-1220, overvoltages are those over 150V (135V
in 100V mode). When the input voltage exceeds
that limit, the power will cut off. It will come back on
automatically when the overvoltage is removed as
long as the voltage has not exceeded 300V. The red
LED labelled EXTREME VOLTAGE SHUT-DOWN
indicates the shutdown condition. The output is also
shut down for extremely low input voltages (those
below 75V, or 65V in 100V mode).
To provide protection against a catastrophic error in
AC mains wiring, dangerously high voltages (those
over approximately 300V) will cause an internal fuse
to blow, but equipment plugged into the Voltage
Regulator will not be damaged.
FUSES AND CIRCUIT BREAKERS
There are one circuit breaker and 8 internal fuses in
the AR-1220.
1. A fast blow 20 amp circuit breaker is used as the
on/off switch. This breaker will trip if the unit’s
20 amp capacity is exceed-ed at any time. If the
circuit breaker is tripped, the on/off switch will
switch off. To reset it, push the switch back to the
on position.
2. A fast blow 1/4 amp fuse is located inside the
unit. This fuse will blow if the unit has been
connected to a voltage that is above the range
of the Extreme Voltage Shutdown circuitry (ap-
proximately 300V). To replace it, the unit must
be completely disconnected from all power and
removed from its rack. The six hex head screws
and one Allen head screw holding the top cover
must be removed.
NOTE: There are two different types of internal
fuses. There are seven 30 amp fuses to protect
the voltage switches against faults in the control
circuits (see the section on Design), and the 1/4
amp fuse mentioned above, to protect the small
transformer against line voltages greater than 300V.
For continued protection, replace fuses only with the
exact same type and rating. The internal fuses are
lo-cated on the main circuit board.
INPUT VOLTAGE MONITORING
The row of ten LED’s at the top left of the front panel
make up a meter that indicates INPUT VOLTAGE.
Only one LED will light up at a time. There are two
red LED’s at the endpoints. When lit, they indicate
that the input voltage may be above or below the
point where it can be restored to the selected nomi-
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