Datasheet

PRELIMINARY
UB20.241
U–Series
24V, 20A, DC-UPS
25. INSTALLATION NOTES
Mounting:
The power terminal shall be located on top of the unit. An appropriate electrical and fire end-product enclosure
should be considered in the end use application.
Cooling: Convection cooled, no forced air cooling required. Do not obstruct air flow!
Installation clearances: 40mm on top, 20mm on the bottom
Risk of electrical shock, fire, personal injury or death!
Turn power off and disconnect battery fuses before working on the DC-UPS. Protect against inadvertent re-powering.
Make sure the wiring is correct by following all local and national codes. Do not open, modify or repair the unit.
Use caution to prevent any foreign objects from entering into the housing.
Do not use in wet locations or in areas where moisture or condensation can be expected.
Service parts:
The unit does not contain any service parts. If damage or malfunctioning should occur during operation, immediately
turn power off and send unit to the factory for inspection!
Wiring and installation instructions:
(1) Connect the power supply to the input terminals of the DC-UPS.
(2) Connect two batteries in series. Connect the free battery terminals to the battery terminals and the center point
to the center tap terminal of the DC-UPS (see Fig. 24-1). Do not install the batteries in airtight housings or
cabinets. The batteries should be installed according to EN50272-2, which includes sufficient ventilation. Batteries
store energy and need to be protected against energy hazards. Use a 30A fuse type ATO
®
257 030 (Littelfuse) or
similar in the battery path. Use an additional 4A fuse type ATO
®
257 004 (Littelfuse) or similar between the center
tap connection and the battery, if the center tap is connected. The battery fuses protect the wires between the
batteries and the DC-UPS. It also allows the disconnection of the batteries from the DC-UPS which is
recommended when working on the batteries or DC-UPS. Disconnect battery fuses before connecting the
batteries.
Please note: Too small or too long wires between the DC-UPS and the batteries can shorten the buffer time or
can result in a malfunction of the DC-UPS. Do not use wires smaller than 4.0mm
2
(or 12AWG) and not longer than
2x1.5m (cord length 1.5m). Avoid voltage drops on this connection.
(3) Connect the buffered load to the output terminals of the DC-UPS. The output is decoupled from the input
allowing load circuits to be easily split into buffered and non buffered sections. Noncritical loads can be
connected directly to the power supply and will not be buffered. The energy of the battery can then be used in
the circuits which require buffering.
(4) Install the fuses when the wiring is finished.
Fig. 25-1 Typical wiring diagram
12V
Battery
Module
+
-
Center
Tap
24V
Power
Supply
+
-
UB20
BAT
24V
+
-
12V
Battery
Module
+
-
24V
IN
24V
OUT
+
-
+
-
Buffered
Load
+
-
Non-buffered
Load
+
-
24V buffered
branches
24V
Non-bufferd
branches
September 2012 / Rev. 1.3 DS-UB20.241-EN preliminary
All parameters are specified at an input voltage of 24V, 20A output load, 25°C ambient and after a 5 minutes run-in time
unless otherwise noted. It is assumed that the input power source can deliver a sufficient output current.
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15/23