Congratulations on your purchase of a Fur-
man PM-8 Power Conditioner/Monitor. The
PM-8 is an ideal accessory for any rack-
mount system.
ProteCtion CirCuitry
The Furman PM-8 protects your delicate electronic
equipment by combining high voltage spike and surge
suppression circuitry with a sophisticated RFI/EMI
interference filter. The fast-acting suppression circuit
responds in less than a nanosecond, clamping transient
voltages to safe levels. The peak clamping voltage is 250
VAC, effective for spikes on any of the three AC conduc-
tors, and the clamping circuitry can absorb a total of up
to 240 joules. These specs indicate a very high degree of
protection compared to competitive products. The RFI
filter is a low-pass type, composed of three high volt
-
age capacitors and a common-mode choke. It passes
the low (50 or 60 Hz) line frequency while rejecting high
frequencies, with maximum attenuation in the region from
1 to 100MHz. Its purpose is to prevent noise from fluo
-
rescent lights, certain motor and lighting dimmers, radio
transmitters, and similar sources of “electronic pollution”
from contaminating the AC line and from there, leaking into
sensitive audio, video, or digital circuits.
The nine (one in front, eight in the rear) circuit breaker
protected outlets are rated at 15 amps. If the total load
on the PM-8 (combining all outlets) exceeds 15 amps,
the circuit will trip, cutting off power to your rack. If this
occurs, reduce the load by unplugging one or more
units from the PM-8. Then push the white button on the
circuit breaker down and in to reset it.
The PM-8 has a master switch for the rear outlets which
lights up when the power is on. The front panel outlet
is unswitched, meaning power is available from it at all
times, regardless of the position of the master switch.
VoltMeter And AMMeter
On the PM-8’s front panel are two LED bar-graph
meters. The voltmeter reads AC voltage from 90 to
135 volts in 5-volt steps. The normal range voltages
are indicated in green, with moderate and extremely
high or low voltages in yellow and red respectively.
The ammeter reads AC current from 0 to 20 amps, in
2-amp steps.Currents above the 15 amp limit read red,
with yellow indicating a warning zone. Note that the
meters continue to read even when the master switch
is off. This was done purposely to allow you to check the
voltage before powering up (though the current meter
will show no load - 0 amps; until the master switch is
in the “on” position. The LED’s are designed for con
-
tinuous, ongoing use. They consume little power, just
a few cents worth per month, like a clock. Please keep
in mind that the ammeter may not read at all if the total
load connected is less than 2 amps (240 watts). This is
a likely occurrence if only relatively low power, signal
processing-type equipment is connected. With the mas
-
ter switch off, the ammeter can still read, but will only do
so if equipment drawing at least 2 amps is connected to
the unswitched outlet.
The PM-8’s ammeter is capable of giving a reliable
indication of current drawn by all kinds of equipment,
thanks to its true-RMS-reading circuitry. This means
that loads like power amplifiers, which are primar
-
ily capacitive or inductive, will read as accurately as
purely resistive loads like heaters. Ammeters that
respond only to average AC current may vary widely
from RMS reading meters. Please note that the
voltage reading is advisory only. The PM-8 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. The PM-
8’s voltmeter has a basic accuracy of ± 5 volts; the
ammeter is ± 2 amps. Should the readings ever be
-
come inaccurate, they can be easily recalibrated by a
qualified service technician. See the section on Meter
Calibration below for details.
220/240V VerSion
(Model PM-8e)
The PM-8E is intended for use with nominal 220 to
240 volt AC lines. The PM-8E differs in the following
ways from the PM-8: The PM-8E is rated at 10 amps.
It has ten rear panel outlets, using the internation-
ally-accepted IEC-320 connectors. The voltmeter on
the PM-8E reads from 210 to 255 volts AC, and the
ammeter reads from 0 to 10 amps AC. The spike and
surge clamping voltage is 500 volts peak.
effeCtS of lightning
And inCorreCt VoltAgeS
Lightning is a natural phenomenon of overwhelming
force that represents the most difficult circumstance
faced by a power protection product. The degree of pro
-
tection a PM-8 can offer depends on the intensity of the
strike. If lightning strikes a distant power line and cause
PM-8 Power Conditioner ownerS MAnuAl
