Positron Teleline 751221, Описание и установка

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(22 pages) Standalone Telephone Unit 1
751221
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1. The Standalone Telephone Unit
The Standalone Telephone Unit, model 751221, provides high voltage isolation
between a telephone line and the drop side of one loop start telephone circuit
(telephone, dial-up modem, or loop start private branch exchange (PBX)).
The unit consists of an isolator card and a power supply mounted inside a small
compact enclosure. The enclosure is molded from fiberglass, making it a
lightweight, flame retardant product of high dielectric strength. Its fiberglass
body limits the possibility of many kinds of infiltration while providing reliable
isolation from external ground potentials.
Its features include the following:
• The unit can operate from either 120 V ac or -24 to 130 V dc. It is not
polarity sensitive, although the live wire should be connected to the fused
terminal.
• The unit’s power supply provides a -24 V dc feed to the telephone on the
subscriber side of the card. In the event of a power outage, communications
are maintained by the onboard battery.
• The Central Office (CO) side circuit components are powered from the
battery feed.
• The unit’s sinusoidal ringing generator can ring up to five standard 500 type
sets and track the CO side frequency, which enables selective ringing.
• The unit withstands 600V power cross (as per UL1950) with automatic
restoration of service after a fault.
• The enclosure resists the infiltration of dust, mist, and water from sprinklers
and operates from 0°C to 50°C.
• The unit’s operating temperature range may be extended to -20°C to +65°C
by removing the battery completely. (Since this would result in no internal
backup power, an external 48 V or 130 V dc supply with battery backup
would be the preferred power source in such a case.)
For a view of the Standalone Telephone Unit enclosure, refer to Figure 1.
For a view of the Standalone Telephone Unit, cover open, refer to Figure 2.