Specifications

Reference Guide
3-7
System Installation Power Supplies and Ringing Generators
Be sure both the front and rear of the chassis are accessible for inserting and removing cards.
The voice, data, and WAN cards, and the power cables, are attached to connectors at the rear
of the chassis. Table 3-1 lists the minimum clearances required between the system chassis and
the nearest objects.
Table 3-1. Minimum Two-Sided Chassis Clearances
3.4 Power Supplies and Ringing Generators
The power supply and ringing generators (8901, 8902, 8903, 8905, 8906, 890620 and 8908)
system can consist of up to two power supplies, two AC-to-DC converters, and up to five
ringing generators. External -48V talk battery and ringing generators may be used instead of
the internal units. Use the following guidelines to determine your power supply and ringing
generator requirements.
3.4.1 System Power (Redundancy)
The system always requires a 120/240 VAC,-48 VDC, or 24 VDC Power Supply. For backup,
you may add a second identical power supply.
Note:
Even though the 24 VDC supply has specifications listed as positive throughout this
manual, it can be used with a negative voltage (-24V). Because of the extremely small
number of applications that would require -24V, it is not covered in this manual.
3.4.2 -48V Talk Battery Requirements
Talk battery is required whenever you have voice user cards in the system, unless (a) all of
those are E&M cards and are used in the Transmission-Only mode, or (b) Type 1 E&M
signaling is used. A -48 VDC power source is also required for use with the ALR 4+4 or ALR
4+3PF External Alarm Cards, OCU-DP cards, and to provide sealing current for BRI cards.
The -48 VDC talk battery can be provided from an external source, or by using a 115 VAC to
-48 VDC Converter. This unit is only available for 115 VAC sources. A similar AC-to-DC
Converter is also available for use with either 115 or 220 VAC.
Clearance Front Rear Top Bottom
Inches 10 15 3/4 2
Centimeters 25 38 2 5