Clear-Com PS-704 - Manual (Page 8)

P S - 7 0 4 F O U R - C H A N N E L P O W E R S U P P L Y 1 - 2
throughout the intercom network, and is usually located in the main station or
power supply.
Clear-Com main stations, power supplies and certain remote stations each
have an auxiliary program input with its own volume control, which allows an
external audio source to be fed to the intercom system.
Visual Signal Circuitry (call lights), a standard feature on all main and remote
stations, allows the user to attract the attention of operators who have
removed their headsets.
Clear-Com manufactures a wide variety of both portable and
fixed-installation units. All are compatible with each other. Clear-Com
intercom systems can also interface with other communication systems and
devices.
DESCRIPTION
The Clear-Com PS-704 is a single rack space, one- to four-channel intercom
power supply which can provide up to 1.2 amperes per channel to operate
Clear-Com beltpacks and remote stations. This power is supplied to any or all
of four channels, and will support up to 40 beltpacks or 10 speaker stations.
Clear-Com’s new fail-safe design automatically shuts down the power to a
channel when a short circuit or electronic overload is sensed on that channel.
The other channels continue to operate normally. Once the fault condition is
removed, the PS-704's fail-safe circuit will bring the power back up, even
under full load conditions. LED indicators signal a fault on any channel. A
line-level program input offers a master input level. Individual program
selects, each with its own send level, are provided for each channel. Use of a
switching power supply allows the PS-704 to operate with any AC line
voltage from 100 volts to 240 volts AC at 50 Hz or 60 Hz. The metal chassis
and extra-thick front panel with integral rack ears maintains legendary
Clear-Com ruggedness.
FAIL SAFE POWER
An intercom power supply has special needs that are not met by traditionally
designed power supplies. An intercom power supply must work in adverse
conditions such as low AC line voltage, momentary shorts on the DC power
lines to the stations, and excessive peak loads during “power-on”conditions.
The following features are incorporated into the PS-704’s power supply:
• AUTOMATIC SHORT CIRCUIT PROTECTION: The PS-704’s
internal power supply checks each channel for a short or current overload.
If it detects a short the power supply will shut down that channel. A short
duration short circuit will not cause the power supply to interrupt power.
• AUTOMATIC OVERLOAD PROTECTION: The PS-704’s internal
power supply senses the difference between shorts and overloads. If an
overload is detected the power supply will shut down that channel. An
overload lasting a short period will not cause the power supply to
interrupt power.