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LDX-U20
SYSTEM DESCRIPTION
The LDX-U20 is a microprocessor controlled DC UPS rated 20 A
12 V and 28 V.
The LDX-U20 monitors the voltage coming from a DC power supply and in case of power failure a backup battery is connected to the load. In normal condition the battery
is kept charged by an integrated battery charger supporting various battery chemistries such Lead-Acid, NiMH, NiCd and Lithium.
CONNECTIONS
The device is equipped with pluggable screw terminals or screw type header. To avoid sparks, do not connect or disconnect the connectors before having previously
turned-off input power and waited for internal capacitors discharge (minimum 1 minute).
In order to comply with UL certification, use appropriate copper cables of indicated cross section, designed for an operating temperature of:
60°C for ambient up to 45°C
75°C for ambient up to 60°C
90°C for ambient up to 70°C.
Strip the connecting ends of the wires according to the indication as shown below and ensure that all strands of a stranded wire enter the terminal connection.
CONNECTIONS AND USER INTERFACE
OPERATING MODE
UPS Mode:
In UPS mode the LDX-U20 protects a load from unwanted power interruption in case of mains failure. An example of UPS connection is given on to the side.
When the input is present LDX-U20 acts as a bypass, connecting the input to the output via the input switch. Meanwhile, if required, the battery is charged. During
bypass there is no voltage conversion, therefore the output supply voltage is equal to the input voltage.
In case of power outage, the LDX-U20 takes energy from the battery to keep the output regulated at "
Backup:
The system is in backup mode if the supply for the output is sourced from the battery (input supply missing). During backup the battery is monitored continuously to
prevent over discharge.
A programmable backup timer is also implemented in order to fix a maximum backup time during power outages. This allows preserving the battery life and shortening
the recharge time, avoiding discharging the battery when not needed.
During backup the internal Coulomb counter is used to give an estimation of the residual charge of the battery.
Backup starts when the output voltage is lower than 90% of the "
Battery charger:
The battery charger supports various chemistries such Lead-Acid, Nickel, Lithium and Super-capacitors. The charging algorithm for each chemistry is given below.
Other charging algorithms can be implemented by request (contact factory).
The battery charger automatically reduces the current to avoid exceeding the maximum input current in case of high current load.
(rating of the power supply connectable to the input)
1. Alarm LED indicator:
ON
when the unit is in backup. Blinks at 1 Hz rate in case of error.
2. USB Port: Used to connect a PC running POWERMASTER or custom application for remote monitoring and
controlling. Firmware update is also possible through USB connection.
3. Temperature sensor: Optional temperature sensor to measure the battery temperature for protection and
temperature compensated charge method. (Contact factory.)
4. Relays dry contacts: 2 relays are present for remote monitoring.
5. INHIBIT input: A signal between 5 VDC and 30 VDC applied to this input inhibits the backup function; this input
is programmable to be active high or active low.
6. BATTERY SENSE connection: Used to accurately sense the battery voltage by considering the cables voltage
drop. It is recommended to use this input when the battery internal resistance measurement is needed.
7. Input connection: 2 poles are provided for input connection. This must be connected to a power supply rated
12 - 28 VDC with a maximum rated current of 20 A.
8. Output connection: 2 poles are provided for output connection. It must be connected to the load to be backed
up with a maximum rated current of 20 A.
9. Battery connection: 2 poles are provided for battery connection. This must be connected to the battery.
Although the unit is protected, please respect the correct polarity.
10. Display area: provides information regarding the device status.
11. Control keys: 4 push buttons are provided to navigate through the menus and to select the various functions.
Nominal output voltage
UPS Mode example
usable in systems with a nominal voltage between
Nominal output voltage
".
".
tech.support@psbel.com
2
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