User manual FURMAN IT1220

[. . . ] Introduction Thank you for your purchase of a Furman IT-1 220 20 Amp Balanced Isolation Transformer, and congratulations on your choice. This specially wound and shielded toroidal isolation transformer is designed specifically to reduce hum pickup by sensitive equipment when ultra-low-noise is a must. Features · Provides precisely balanced AC power for ultra-low-noise installations · Typically gives a 16 dB improvement in background noise floor in system wide installations · Toroidal transformer with center-tapped secondary is the most efficient, compact design, with least magnetic field leakage · Soft Start circuit prevents turn-on transients and high inrush currents · Faraday shield reduces electrostatic coupling between primary and secondary · Extreme Voltage Shutdown circuit protects against dangerously high or low input voltages · Microprocessor-controlled "smart" AC voltmeter monitors line voltage, flashes alerts for marginal and extreme conditions · Provides basic power conditioning functions (spike suppression, RFI filtering) · Ground fault interrupter (GFCI) protection Description Designed for the most critical, ultra-low-noise installations, the IT-1220 can supply 20 amps of balanced AC power to a recording studio, video or film production facility, broadcast station, etc. Its purpose is to drastically reduce hum and buzz caused both by ground currents from power supply filtering and by radiation from supply cables into sensitive signal sources like guitar pickups and microphones. [. . . ] It not only dramatically reduces the noise floor but also noticeably improves dynamic range and sonic clarity. The IT-1230's heart is a specially wound and shielded toroidal isolation transformer with a center-tapped secondary. It is housed in a 3-unit (5. 25" high) rack mount chassis. The back panel provides a 30-amp twistlock inlet and outlet, plus ten 20A balanced Edison outlets, widely spaced with plenty of clearance for "wall warts"; the front panel provides two more outlets. An IT-1230 can be installed in minutes, though you may require some help in choosing and wiring an appropriate supply cable. The IT-1230 provides clean and completely safe power--there is no need to "lift grounds" or compromise the integrity of safety ground wires to achieve hum reduction. Special features include an accurate, self-checking AC voltmeter that not only measures normal voltages, but also flashes eye-catching special pattern alerts for off-scale but not extreme conditions (80-90 or 130-140 volts); an Extreme Voltage Shutdown circuit to cause a protective shutdown if the unit is exposed to dangerous voltages (like accidental connection to 220V); and a special "Soft Start" circuit to prevent the large inrush surge currents and spikes that would otherwise occur at turnon and turn-off with such a large transformer. 960129-2332 Features Provides precisely balanced AC power for ultra-low-noise installations Typically gives a 16 dB improvement in background noise floor in systemwide installations Toroidal transformer with center-tapped secondary is the most efficient, compact design, with least magnetic field leakage Soft Start circuit prevents turn-on transients and high inrush currents Faraday shield reduces electrostatic coupling between primary and secondary Extreme Voltage Shutdown circuit protects against dangerously high or low input voltages Microprocessor-controlled "smart" AC voltmeter monitors line voltage, flashes alerts for marginal and extreme conditions Provides basic power conditioning functions (spike suppression, RFI filtering) Ground fault interrupter (GFCI) protection 1-9843 Background In much the same way that balanced audio lines can reduce the pickup of hum and other types of electromagnetic interference (EMI), the use of balanced AC power lines in sensitive audio, video, or computer installations can make an enormous difference in system noise. But power distribution in North America, unfortunately, is not balanced. The distribution standards currently in use were derived from practices established over a century ago, when electric power use was limited to lighting and motors--long before any EMI-sensitive applications existed. The emphasis then was on convenience (from the power utilities' standpoint) and safety, but not noise cancellation. The result was a three-wire distribution scheme in which 120V branch circuits have a hot wire and a neutral wire, with the neutral tied to a third wire connected for safety to an earth ground. The third wire does not carry any current unless there is a short circuit. This unbalanced scheme causes hum in audio circuits for two main reasons: First, the current flowing in the hot wire induces hum in any other nearby wires, which may carry vulnerable lowlevel audio signals. Second, because the impedance of chassis and cable shielding to ground is not zero, ground current flowing from power supply capacitors and from EMI pickup causes a voltage drop at 60 Hz and its harmonics which is added to the audio signals. With a center-tapped isolation transformer, the AC power feeding a studio can be balanced at its source. The current-carrying wires then are no longer "hot" (120V) and "neutral" (0V), but two equal and opposite lines of 60V each (referenced to the safety ground connected to the center tap), which add to 120V. This type of power, when run around a room, does not induce hum into nearby audio wiring, because the two power conductors induce equal and opposite voltages that cancel each other out. Similarly, ground currents are all but eliminated by the same common-mode cancellation effect. No longer is it necessary to adopt cumbersome and expensive star-ground systems or use massive bus bars or heavy ground rods. All such systems are doomed to yield only mediocre results because of the impossibility of reducing the ground impedance to zero. The common-mode rejection of a truly balanced AC supply is far simpler, cheaper, and more effective. Balanced, or "technical" power, is recognized by the US National Electrical Code (Article 530) for critical, low noise applications. INPUT 80 - 140 VAC 60 HZ 30 AMPS MAX 60 / 120V 1 Ø AC GFCI PROTECTED 30 AMPS MAX BREAKER GROUP 60 / 120V 1 Ø AC GFCI PROTECTED 20 AMPS MAX B 20 WARNING -- TECHNICAL POWER DO NOT CONNECT TO LIGHTING EQUIPMENT. [. . . ] You can restore operation after a test by once again turning the unit ON. IT-1230 SPECIFICATIONS Output current: 30 amps (3600 watts at 60/120 V 1 ø AC, 60 Hz)-- Technical power, for electronic equipment (not lighting) only, per NEC Article 530. Normal, 90-130; Marginal (flashes alert), 80-90 or 130-140; Extreme (causes shutdown), below 80 or above 140 30A NEMA L14-30P twistlock inlet connector, rear Rear: 30A NEMA L14-30R twistlock plus 10 NEMA 5-20 (20A Edison) outlets Front: 2 NEMA 5-15 outlets suitable for 20A use Voltage Ranges: Inlet: Outlets: Isolation, Input to Output: Breakdown Voltage: 1500V minimum Leakage current: 40 mA maximum Capacitance: 300 pf maximum Turns Ratio: 1:1; windings separated with Faraday shield Transformer Regulation: (Full load/no load) 3% at full load Spike Protection Modes: Line to neutral, neutral to ground, line to ground Spike Clamping Voltage: TVSS rating of 400 volts peak, L-N, N-G, L-G (tested to UL-1449) Spike Response time: 1 nanosecond Maximum surge current: 6, 500 amps (8 x 20 mS pulse) Maximum spike energy: 80 joules per mode, 240 joules total Noise attenuation: Differential mode: Greater than 40 dB Transverse mode: Greater than 60 dB Common mode: Greater than 80 dB, 1 to 200 MHz Mechanical: Dimensions: 5. 25" H x 19" W x 17" D. Construction: Steel chassis, powder coated; glass epoxy printed circuit boards 8. 5 watts for display and control circuits, independent of actual load Power Consumption: The IT-1230 is manufactured in the United States of America Three Year Limited Warranty The Furman IT-1230 is warranted against failures due to defective parts or faulty workmanship for a period of three years after delivery to the original owner. During this period, Furman will make any necessary repairs without charge for parts or labor. [. . . ]