Positron 7885-2 Istruzioni per l'uso e l'installazione
Standalone Power Supply Unit
120 V ac to 48 V dc, 7885-2 & 7885-3
Description and Installation
DOCUMENT CONTROL INFORMATION
Document Part Number: 7885-24-02, Rev 4
Document Issue Number: 4
Publication Date: January 07, 2003
Document ID: (o02j2000.fm)
CONFIDENTIALITY NOTICE
The information contained in this document is the property of Positron Inc. Except as specifically
authorized in writing by Positron Inc., the holder of this document: 1) shall keep all information
contained herein confidential and shall protect same in whole or in part from the disclosure and
dissemination to all third parties, and 2) shall use same for operating and maintenance purposes only.
DISCLAIMER NOTICE
Although Positron Inc. has made every effort to ensure the accuracy of the information contained
herein, this document is subject to change without notice.
TECHNICAL CUSTOMER SUPPORT
Should a problem arise, contact your customer support department. If the problem cannot be resolved
by your support department or if you have any questions, contact Positron’s Technical Customer
Support department at 1-888-577-5254.
© 2003 Positron Inc.
Teleline Isolator is a registered trademark of Positron Inc.
Product names, other than Positron’s, mentioned herein may be trademarks and/or registered trademarks
of their respective companies.
Contents i
o02j2000TOC.fm
1. The Standalone Power Supply Unit and Battery Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Hardware Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Technical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1 Mechanical Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1.1 Wall Mount. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1.2 Teleline Shelf Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Electrical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Battery Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5. Service and Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
(20 pages) Standalone Power Supply Unit 120 V dc to -24 V dc 1
7885-2 & 7885-3
o02j2001.fm
1. The Standalone Power Supply Unit
and Battery Unit
The Standalone Power Supply Unit and its Battery Unit, models 7885-2 and
7885-3, are described in one document because together they form a fully
functional uninterruptible power supply. They are always sold together, as a pair.
The Standalone Power Supply Unit, model 7885-2, converts 120 V ac, 60 Hz to
48 V dc, and may be configured for an output that is either floating or referenced
to station ground. This large capacity supply can be used to power a fully loaded
Three, Five or Eight-card Shelf.
The Battery Unit, model 7885-3, holds two maintenance-free backup batteries, as
does the Power Supply Unit, model 7885-2. When the 7885-2 is connected to the
7885-3, the 7885-2 provides 5.7 ampere-hours of battery charge at 48 V dc. The
7885-2 alone cannot provide battery backup.
The installation kit consists of the Standalone Power Supply Unit and its Battery
Unit, in durable, metal enclosures. The kit contains connecting cables, and
mounting hardware.
Attention
The Standalone Power Supply Unit and its Battery Unit are intended to
provide a shelf with uninterruptible 48 V dc, either floating or referenced to
station ground. Teleline equipment having conflicting requirements cannot
be used with this supply. For further information, refer to Table 3 and Table
4.
For a view of the Standalone Power Supply Unit and its Battery Unit, refer to
Figure 1.
7885-2 & 7885-3
2 Standalone Power Supply Unit 120 V dc to -24 V dc
Figure 1 Models 7885-2 & 3
3-7/8"
MOUNTING TRAY
7885-2 RIGHT SIDE VIEW
16-1/4"
7885-2 FRONT VIEW
POSITRON # 7885-2
MOUNTING
TRAY
INPUT CABLE
9-2/3"
INPUT FUSE
ANCHORING BRACKET
OUTPUT CONNECTOR
3-7/8"
7885-3 RIGHT SIDE VIEW
16-1/4"
7885-3 FRONT VIEW
POSITRON # 7885-3
9-2/3"
BATTERY
TEST
+
POWER
CHARGE
-
50BC1;>
$0<?
Standalone Power Supply Unit 120 V dc to -24 V dc 3
7885-2 & 7885-3
The features of the unit (comprised of the power supply and battery units)
include the following:
•The unit may be used with both the old and new generation Three, Five or
Eight-card Teleline Shelf.
•The unit provides floating 48 V dc at up to 1.3 A from a standard 120 V ac
source. When wiring to a shelf, the supply output may be left floating or
referenced to station ground.
•The unit uses standard full wave rectification, filtering, and voltage
regulation to perform the AC to DC conversion.
•When model 7885-2 and 7885-3 are connected together, they provide 5.7
ampere-hours of charge at 48 V dc. The batteries are kept charged by the
power supply while it is operating from the AC source.
•A fuse provides overcurrent protection at the input, while a second at the
output provides short circuit protection.
•A green “Power ON”LED located on the front panel indicates the presence
of 48 V dc output.
•A red “CHARGE”LED located on the front panel indicates that the batteries
are undercharged.
•A pair of battery test jacks permit an easy assessment of batteries status.
7885-2 & 7885-3
4 Standalone Power Supply Unit 120 V dc to -24 V dc
2. Hardware Description
For the block diagram of model 7885-2, refer to Figure 2.
Figure 2 Block Diagram
Under
Voltage
Detection
Rectifier
Output
Breaker
Input
Breaker
Transformer Voltage
Regulator
Batteries
Filter
120 V ac in
48 V dc out
(floating)
Current
Limit
Standalone Power Supply Unit 120 V dc to -24 V dc 5
7885-2 & 7885-3
The following is a description of the elements of the Standalone Power Supply
Unit block diagram.
Input Breaker
The Input Breaker circuit on the right side panel of the 7885-2 is a 1 A circuit
breaker providing standard input protection.
Transformer
The Transformer provides 1500 V isolation while stepping down the voltage for
the regulator.
Rectifier
The Rectifier fully rectifies the AC input voltage.
Filter
The Filter is made of a big electrolytic capacitor that filters the 60 Hz input to
provide a DC voltage to the regulator.
Voltage Regulator
The Voltage Regulator takes the filtered voltage from the input and gives out 48
V dc to the output.
Current Limit
The Current Limit circuit is a linear current limit circuit that drops the output
voltage as the current increases past the limit value.
Output Breaker
The Output Breaker circuit on the front panel is rated at 2 A and provides short
circuit protection to the power supply.
Batteries
Each Battery is a 12 V, maintenance-free Dryfit type. They require no more than
24 hours to reach full charge, and can hold 5.7 ampere-hours of charge. This
corresponds to 570 mA over a 10-hour discharge period. Since the four batteries
are connected in series, this current is available at 48 V dc.
Under Voltage Detection
The Under Voltage Detection circuit monitors the batteries and lights a LED
when the voltage approaches the minimum specified voltage of the power supply.
7885-2 & 7885-3
6 Standalone Power Supply Unit 120 V dc to -24 V dc
3. Technical Specifications
For a listing of the unit’s electrical specifications, refer to Table 1. For a listing of
the unit’s physical specifications, refer to Table 2.
Table 1 Electrical Specifications (measured at 77°F or 25°C,
50% R.H.)
Table 2 Physical Specifications
Parameter Specifications
Battery GS Battery 12V, 5.7 A-h
P/N PE12V7F1 or equivalent
Input station voltage 104 to 127 V ac
Input power at full load 160 VA
Nominal output voltage 48 V dc
Maximum output current 1.3 A
Output ripple voltage 400 mVpp
Regulation, line <7.0%
Regulation, load <8.0%
Input/output isolation 1500 V @ 60 Hz for 1 minute
Parameter Specifications
Operating temperature range +32°F to +122°F (0°C to + 50°C)
Height 3.9”(9.9 cm)
Width 16.3”(41.4 cm)
Depth 9.7”(24.6 cm)
Weight (7885-2)
Weight (7885-3)
21 lbs (9.5 kg) approx.
15 lbs (7.0 kg) approx.
Questo manuale è adatto per i seguenti modelli
1
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