BEL LDX-U20 User manual

USER MANUAL
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LDX-U20
12/24 V 20 A High Performance DC-UPS

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CONTENTS
1 System description 4
2 Features and benefits 5
3 Functional description 6
3.1 Remote monitoring and controlling 6
3.1.1 USB 6
3.1.2 Digital input 6
3.1.3 Dry contact outputs 6
3.2 Backup 7
3.3 PC shutdown and automatic restart 7
3.4 Battery health monitor 9
3.5 Battery resistance measurement 9
3.6 Battery charger 10
3.7 Coulomb counter 11
3.8 Cold start 11
4 Installation 12
4.1 Connecting the input to the power supply 12
4.2 Connecting the load 12
4.3 Connecting the battery 12
4.4 Connecting the temperature sensor 12
4.5 Connecting the INHIBIT input 12
4.6 Dry contacts 13
4.7 Battery sense connection 13
5 User interface 14
5.1 Status 15
5.2 Settings 16
5.2.1 Input nominal voltage 16
5.2.2 Battery chemistry 16
5.2.3 Battery nominal voltage 16
5.2.4 Battery capacity 16
5.2.5 Battery charge voltage 16
5.2.6 Battery charge current 16
5.2.7 Battery deep discharge voltage 17
5.2.8 Battery low voltage 17
5.2.9 Battery nominal internal resistance 17
5.2.10 Battery maximal internal resistance variation 17
5.2.11 Battery maximum temperature 17
5.2.12 Battery minimum temperature 17
5.2.13 Battery lifetime 17
5.2.14 Maximum backup time 18
5.2.15 Inhibit polarity 18
5.2.16 Screen contrast 18
5.2.17 Screen backlight 18
5.2.18 Screen timeout 18
5.2.19 Buzzer state 18
5.2.20 Date 18
5.2.21 Time 19
5.2.22 PC shutdown enable 19
5.2.23 PC shutdown delay 19
5.2.24 PC shutdown time 19
5.2.25 PC restart minimum OFF time 19
5.2.26 PC OFF detection current threshold 19
5.2.27 PC OFF detection timer 19
5.2.28 Relay 1 (Ready) 20
5.2.29 Relay 2 (Backup) 20

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5.3 Info 20
5.3.1 Firmware version 20
5.3.2 Serial 20
5.3.3 Name 20
5.3.4 Power ON cycles counter 20
5.3.5 Operating time 21
5.3.6 Battery installation date 21
5.3.7 Battery operating time 21
5.4 Logs 21
5.5 Wizard 21
6 Events and Alarms 22
7 Physical dimensions 25

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1 SYSTEM DESCRIPTION
Use latest device Documentation, Software and Firmware to ensure reliable operation of the system (downloadable from
belfuse.com/power-solutions).
The LDX-U20 is a microprocessor controlled DC UPS rated 20A (rating of the power supply connectable to the input) usable in systems with
a nominal voltage between 12V and 28V.
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.
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Figure 1. Front panel view
1. Alarm LED Indicator: It is ON when the unit is in backup. It blinks at 1Hz rate in case of error.
2. USB Port: Used to connect a PC running the POWERMASTER application for remote monitoring and controlling. Firmware update is also
possible through USB connection.
3. Temperature Sensor Connection: Used to connect a temperature sensor (P/N: WNTC-2MT) to measure the battery temperature for
protection and temperature compensated charge method.
4. Relays Dry Contacts: 2 relays are present for remote monitoring. See §3.1 for more details.
5. Inhibit Input: A signal between 5VDC and 30VDC applied to this input inhibits the backup function; this input is programmable to be active
high or active low (see §4.5).
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 (see §4.7).
7. Input Connection: 2 poles are provided for input connection. This must be connected to a power supply rated 12…28VDC with a
maximum rated current of 20A (see §4.2).
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 20A (see §4.2).
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. (see §4.3)
10. Display “Input” Area: provides information regarding the unit’s input (see §5.1).
11. Display “Output” Area: provides information regarding the unit’s output (see §5.1).
12. Display “Battery” Area: provides information regarding the battery (see §5.1).
13. Control Keys: 4 push buttons are provided to navigate through the menus and to select the various functions.

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2 FEATURES AND BENEFITS
The Main Features are:
• Integrated battery charger for multi-chemistry batteries with charging current up to 5A.
• Automatic sensing of input voltage, load current and battery current.
• Protections against battery reverse polarity connection and over current when operating from the battery.
• Battery “health monitoring” system: measuring battery internal resistance, battery temperature and providing a Coulomb counter.
• User settable maximum backup time.
• Remote input to inhibit the UPS function.
• Connection of a battery thermal sensor (optional).
• Integrated data logger with time stamp: all events / errors are logged in the internal memory and downloadable through the USB
interface.
• Automatic PC shutdown/restart function (see §3.3)
Embedded User Interface:
• 4 buttons and 1 color graphic CSTN LCD, Displays the set-up, status, measures and alarms
• Online device configuration.
• USB port for remote monitoring and configuration.
• Dry contacts for status monitoring
“POWERMASTER” PC Application:
• Connection through USB interface.
• Remote monitoring and configuration.
• Firmware upgrade.
• Same functionalities of the embedded user interface with the ease of the PC benefits.

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3 FUNCTIONAL DESCRIPTION
A simplified block diagram of the LDX-U20 is shown in Figure 2.
Figure 2. LDX-U20 simplified block diagram
LDX-U20 is a high performance digitally controlled DC-UPS that can be used in any DC system with a rated voltage between 12V and 28V
and up to 20A of input current.
It includes a battery charger capable of charging Lead-Acid, Ni-MH and Li-ION batteries with a rated voltage between 12V and 28V and able
to deliver a charge current up to 5A.
The input voltage is continuously monitored by the microprocessor. In case of a power outage the battery is connected to the load
instantaneously through an active switch, reducing the power loss to a minimum.
The product offers additional features to improve the performance and the reliability of the system, which are described below.
3.1 REMOTE MONITORING AND CONTROLLING
3.1.1 USB
The USB interface allows the communication with the proprietary POWERMASTER software (available for download at www.nextys.
com) which allows the full control and monitoring of the LDX-U20 unit with the ease of the PC.
3.1.2 DIGITAL INPUT
An opto-isolated input allows the inhibition of the backup function. The polarity of the input can be defined using the Inhibit polarity
setting (see §5.2.15).
3.1.3 DRY CONTACT OUTPUTS
2 relays are present on the LDX-U20. User can chose which event activates the relay and the polarity. The list of events is the following:
NAME DESCRIPTION DEFAULT SETTING
Backup Active when the system is running on the batteries. Relay 2
SoC < 25% (Low Battery) Active when the State of Charge (SoC) of the battery is below 25%. Unused
Battery life time expired Active when the battery life time counter is exceeding the value specified on §5.2.13 Relay 1
Battery Ri too high Active when the measured battery internal resistance (Ri)> alarm threshold.
The threshold is specified using setting §5.2.9 and §5.2.10. Relay 1
Battery failure Active when the battery could not be charged correctly. Relay 1
Battery under voltage Active when the battery voltage is below the value specified on §5.2.7 Unused
Battery backup time left < 25% Active when the remaining backup time is higher than the 75% of the maximal backup
time defined on §5.2.14 Unused
PC OFF signal Activated by the PC shutdown and automatic restart function. See §3.3 for details. Unused
Table 1. Relays signals
By default both relays polarity is set to NC (Normal Close).

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3.2 BACKUP
The system is in backup 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 (see §5.2.7).
A programmable backup timer (see §5.2.14) 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, this information is given to
the user on the LCD in form of remaining % and through the ready relay which starts toggling at 1Hz once the battery charge is < 20%.
3.3 PC SHUTDOWN AND AUTOMATIC RESTART
PC shutdown: In case the LDX-U20 is used to supply a PC it is possible to automatically shut down the PC after an adjustable time
of backup. For this the PC must run the POWERMASTER application (provided free) and must be connected through USB. Optionally
POWERMASTER can call a task on the PC before shutting down, for example to backup some sensitive data.
Automatic restart: LDX-U20 is able to automatically restart a PC which was powered OFF by mistake, for example in case of the
Operating System (OS) crash. The user may adjust an output current threshold and a timer used for detecting the PC OFF status. In
order to restart the PC the LDX-U20 toggles the output OFF and then ON again. User must enable in the PC BIOS the automatic start in
case of supply ON.
Note: The LDX-U20 cannot interrupt the supply flow from the input to the output. Therefore the user must use one of the LDX-U20
available relays (by activating the PC OFF signal on it) in order to enable automatic PC restart when the input supply is present. The
relay contact (rated 2A/30Vdc) must be wired in series to the device output using a 4A fast cartridge fuse (Littlefuse 0217004.HXP or
equivalent). Be careful to respect maximum current rating of the fuse.
In case the load (PC) current exceeds the LDX-U20 dry contact rating the use of an external relay with suitable current/voltage rating is
needed, relay coil voltage shall match output voltage. It should be driven by the LDX-U20 internal dry contact.
Figure 3. Internal relay Figure 4. External relay

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The diagram below shows the LDX-U20 behavior when Shutdown and automatic restart is enabled.
Figure 5. Shutdown and restart chart
PARAMETER NAME DESCRIPTION
E1 Backup Power failure on the line happens. System enters backup mode.
E2 Automatic PC shutdown
The POWERMASTER sends a shutdown command to the PC. Optionally: a task is called before
shutdown.
This event is triggered by the “PC shutdown delay” (§5.2.23) or “Battery low alarm” (§5.2.8),
whatever comes first.
E3 Unexpected PC shutdown The PC shutdowns in an unexpected way, for example caused by OS crash.
E4 PC restart
LDX-U20 detect the PC being OFF because the output current was lower than Ioff current
threshold for T4 time. As a consequence LDX-U20 generates an ON->OFF->ON cycle on its
output.
T1 PC shutdown delay User settable (§5.2.23). Time between start of backup and start of PC shutdown procedure.
T2 PC shutdown time User settable (§5.2.24). Time between start of shutdown procedure and output voltage OFF.
This time must be set longer than the maximum time the PC takes to complete the shutdown.
T3 PC restart minimum OFF time
User settable (§5.2.25). T3 is the delay used between the return of the input voltage and the
activation of the output. The same time is used by the automatic restart function as power OFF
time to restart the PC. The value must be big enough for the PC to detect the supply
ON->OFF->ON cycle to restart.
T4 PC OFF detection timer User settable (§5.2.27). Minimum time at which the output current must be below the Ioff current
threshold to trigger the automatic PC restart (PC supply ON->OFF->ON cycle).
Ioff PC OFF detection current
threshold
User settable (§5.2.26). Current threshold used to detect PC OFF status. This value must be
lower than the minimum PC current consumption when this is ON.
Table 2. Shutdown and restart
The parameters are settable through the LDX-U20 LCD or using the POWERMASTER application. The checkbox “Run on startup” must be
checked on POWERMASTER when PC shutdown function is used, select “Start in tray” to start in minimized into the windows system tray.
To inhibit the software from calling the shutdown command user can select the “Inhibit shutdown” check box.

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Figure 6. PC shutdown settings
3.4 BATTERY HEALTH MONITOR
The battery health monitor is composed of:
• Internal resistance (Ri) measurement: The resistance is periodically measured. The internal resistance is a good indicator of the battery
health status; a sudden increase of the internal resistance indicates a potential problem on the battery or on the battery wiring (see §3.5).
• Temperature (T) measurement: The battery temperature is monitored through an optional temperature sensor (P/N: WNTC-2MT). The
battery charger takes into account the battery temperature and provides a temperature compensated charging voltage. In case of over
temperature the system disconnects the battery to prevent damage.
• Coulomb counter: It allows having a quick estimation of the remaining battery capacity and consequently the available backup time.
• Deep discharge protection: It protects against the deep discharge of the battery which can lead to its irreversible damage.
3.5 BATTERY RESISTANCE MEASUREMENT
The battery internal resistance (Ri) is measured by injecting a defined AC current through a constant current source (CCS) in the battery and
measuring the AC voltage drop across the battery terminals. The principle is represented in Figure 7.
The injected AC current I(AC) is flowing also through the cables + connectors resistance - “Rcables”.
Figure 7. Internal resistance measurement

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Without using the battery sense connection as shown in Figure 9 the AC voltage drop is measured across the battery connection terminals
on the LDX-U20. The measured resistance will be in this case:
Rmeasured=Ri+Rcables. When high Ah batteries and / or small and long cables are used Rcables can be > Ri. Anyhow a connection problem
as for example a loose contact can be detected by this measurement method.
By using the battery sense connection (a “Kelvin” type connection) as shown in Figure 10 the AC voltage drop is measured directly at the
battery terminal. In this case the measured resistance is exactly the battery internal resistance Ri, independently on the cables length and
size.
It is recommended to use this method to have an accurate reading of the battery internal resistance and thus an accurate prediction of the
battery health status.
If the battery sense cables length is > 2m it is recommended to twist the 2 wires together in order to increase the noise immunity.
3.6 BATTERY CHARGER
The battery charger supports various chemistries such Lead-Acid, Nickel, Lithium and every other battery chemistry assuming that the
charging voltage and charging current values are provided by the battery manufacturer. The charging algorithm is shown on Figure 8. Other
charging algorithms can be implemented by request.
The user must set to the unit the following parameters to allow the charger to perform correctly:
• Battery chemistry: selectable between Lead-Acid, Nickel, Lithium (see §5.2.2).
• Battery nominal voltage: between 12V and 28V (see §5.2.3).
• Battery capacity: between 1.2Ah and 150Ah (see §5.2.4).
• Battery charging voltage: provided by the battery manufacturer (see §5.2.5).
• Battery charging current: provided by the battery manufacturer (see §5.2.6).
• Battery deep discharge voltage (see §5.2.7).
The battery charger automatically reduces the current to avoid exceeding the maximum input current (20A) in case of high current load. For
example if the load is consuming 19A and the charger current is set to 3A, the charger current is automatically reduced to 1A to avoid the
20A input current limit.
The charger voltage is independent on the input voltage (power supply), and is user settable.
Figure 8. Battery charging algorithm
The battery charge terminates in case at least one of the following conditions are satisfied:
• Low current: The measured battery current is lower than 10% of the “Battery charge current”.
• Timer: the charge is terminated after the battery has been charged for a predetermined amount of time. The value is automatically
calculated by the device.
For Nickel batteries only the following conditions are also checked:
• Temperature Cutoff (TCO): The battery temperature if higher than the “Battery maximal temperature” (§5.2.11) minus 3°C for more than one
minute. For example if the maximal battery temperature is set to 60°C, the charge terminates in case the temperature is higher than 57°C.

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• Rate of Temperature Increase (ΔT/dt): The battery temperature is rising at a rate equal or superior then 1°C/min. To avoid unattended
end of charge don’t place the system on an ambient with rapid changes of temperature (for example exposed to direct sunlight).
Warning: In order to avoid potentially hazardous situations including fire hazard, safety recommendations must be followed. Only
authorized staff can install the unit.
Warning: For Lithium cells the balancing and protection circuit must be included in the battery pack.
For nickel batteries the use of the external temperature sensor is mandatory. The sensor must be placed in contact with the battery.
3.7 COULOMB COUNTER
LDX-U20 measures the current flowing from/to the battery to keep track of the capacity available on the battery. The capacity is measured in
Ampère Hours [Ah]. The value shown is based on the following assumptions:
• The value shown is just informative and does not represent the real state of charge of the battery in some circumstances, for example if
the battery is damaged.
• When the battery is connected for the first time or the system starts from OFF, the system assumes the battery is fully discharged and
start with 0Ah counter.
• For Lead acid batteries only, during battery charge an approximation of charge is done checking the battery voltage.
• Once the battery is fully charged the system sets the counter to the nominal capacity specified by the user (§5.2.4).
3.8 COLD START
The cold start is a procedure that allows turning ON the UPS without the input power. This procedure is used to turn ON the UPS to operate
during a power interruption or to determine if the UPS will not turn ON due to a bad input power. This practice is also a method to see if the
battery connected to the LDX-U20 is functional.
In cold start the DCU 20 will remain ON for at least 60 seconds independently from the battery voltage being under the deep discharge
threshold, the inhibit input and the backup timer.
After the first 60 seconds the device stays ON until the battery is not deep discharged, the “Max backup timer” is not expired or the inhibit
input is not active.
If the input supply returns during cold start the device reverts to normal operation.
To cold start the LDX-U20:
• Press and HOLD simultaneously the menu button and OK button until you see the welcome message on the screen. On the status
screen the input voltage status is indicated as “COLDSTART”.
• RELEASE the buttons.

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4 INSTALLATION
Warning: In order to avoid potentially hazardous situations including fire hazard, safety recommendations must be followed. Only
authorized staff can install the unit.
4.1 CONNECTING THE INPUT TO THE POWER SUPPLY
The LDX-U20 must be connected to a DC power supply rated between 12VDC and 28VDC with a maximum output current of 20A. Use only
60/75 Class I copper 1.5…2.5mm2 wires stripped 6...7.5mm. The tightening torque must be 0.5…0.6Nm.
Please respect the wiring polarity!
Note: The input current is equal to the load current plus the current needed by the battery charger to recharge the battery.
Caution: This input is designed to be connected ONLY to a short circuit protected power supply; connecting a battery to this input or
other DC sources with not defined current limitation may seriously damage the unit or the load and even result in fire hazard.
4.2 CONNECTING THE LOAD
The LDX-U20 must be connected to a DC load rated between 12VDC and 28VDC / maximum 20A. Use only 60/75 Class I copper
1.5…2.5mm2 wires stripped 6...7.5mm. The tightening torque must be 0.5…0.6Nm.
Please respect the wiring polarity! Please check the load and the power supply are rating compliant.
4.3 CONNECTING THE BATTERY
The LDX-U20 must be connected to a battery with nominal voltage between 12VDC and 28VDC with up to 150Ah capacity. Higher capacity
batteries can also be used at the expense of a longer charging time. Use only 60/75 Class I copper 1.5…2.5mm2 wires stripped 6...7.5mm.
The tightening torque must be 0.5…0.6Nm.
Caution: The battery shall be connected to the LDX-U20 through a 30A ATO fuse (or equivalent). Even is the unit is electronically
protected against short circuit it is mandatory to use a fuse for safety reasons.
Please respect the wiring polarity!
Avoid keeping the LDX-U20 connected to the battery for long time when not used. Although the current consumption from the battery when
the unit is OFF is very low (about 30µA) it can discharge the battery in the long time.
4.4 CONNECTING THE TEMPERATURE SENSOR
An optional temperature sensor (P/N: WNTC-2MT) can be connected to its input on the front panel. The temperature sensor is provided
with 2m long cables and must be fixed to the battery body to measure its temperature (an adhesive pad can be used). When the sensor is
connected the battery temperature is automatically displayed on the LCD and a temperature compensated charge is activated when charging
Lead-Acid batteries.
4.5 CONNECTING THE INHIBIT INPUT
An opto-isolated digital input is provided. A digital signal between 5VDC and 30VDC must be applied to this input to enable the INHIBIT
function. By default when the signal is 0V (or the INHIBIT input is not connected) the unit will switch the load to the battery as soon as the
input voltage is no more present. Applying a signal to this input inhibits the backup function and the load can be switched OFF as soon at the
input fails with no battery backup. The polarity of this input can be changed as explained in §5.2.15.

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4.6 DRY CONTACTS
2 relays’ dry contacts are provided on the LDX-U20. Connect the 2 relays dry contact using 60/75 Class I copper 0.15…0.5mm2 wires
stripped 7...8mm. The connector is provided with spring terminals.
Note: the 2 relays contacts have one pole in common.
4.7 BATTERY SENSE CONNECTION
Figure 9. Battery connection without sense Figure 10. Battery connection with sense
The battery sense connection is optional and it is recommended to use it to have an accurate measurement of the battery internal resistance
(see §3.5).
Caution: please respect the polarity of the battery sense connection!

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5 USER INTERFACE
Power ON screen:
This screen is shown at power ON. It shows the device name, serial
number and firmware version.
Status:
This is the default view where the user can find the most relevant
information about the device status. The system always falls back to
this view after 60s of inactivity (no key pressed).
Settings:
All the device settings are configurable from this menu. Use the UP/
DOWN KEY to navigate through the parameters. Press the OK KEY to
enter/exit the editing mode. In editing mode use the UP/DOWN KEY to
change the highlighted value.
Info:
Device information such as firmware version, serial number and device
name is visible from this menu.
Logs:
All the alarms and event are logged in a circular buffer and visible from
this screen. Use the UP/DOWN KEY to navigate through the logs.
Wizard:
The wizard helps the user to configure the system through a series of
screens.
Table 3. User interface layout

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SYMBOL NAME FUNCTION
MENU KEY Scrolls between menus.
DOWN KEY Scrolls down menus and values.
UP KEY Scrolls up menus and values.
OK KEY Confirms selection.
Table 4. User interface keys
The GUI is composed of 5 main menus which are selectable using the MENU KEY as shown on Table 3. The description of each menu is
given below.
5.1 STATUS
The status screen shows the measurement and statuses to ease the system diagnostic. The screen is divided in three main sections
identified by the symbols shown below:
Input: The measured input voltage and current is shown in this section. In case of problems with the input the background
color of the symbol changes from green to red. A message with the cause appears.
Output: The measured output voltage and current is shown in this section. In case of problems with the output the
background color of the symbol changes from green to red and a message with the cause appears.
Battery: The battery voltage, current, temperature, resistance and charge are shown in this section. In case of problems with
the battery the background color of the symbol changes from green to red and a message with the cause appears. During
charging and discharging the symbol background color changes to orange and the number of bars drawn inside reflects the
charge status. During discharging and charging an arrow drawn beside the symbol reflects the direction of the current flowing
through the battery, pointing towards the battery during charging.
Table 5. Status screen symbols
Furthermore in case of problem a full screen alarm message appears on the screen after 1min of
inactivity (no key pressed). The message can be removed pressing the MENU KEY.

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5.2 SETTINGS
The setting menu contains all the configurable parameters available to the user. Use the UP/DOWN KEY to navigate through the menu items.
Press the OK KEY to enter and exit the editing mode, while in editing mode use the UP/DOWN KEY to change the selected value.
5.2.1 INPUT NOMINAL VOLTAGE
Used to set the nominal input voltage on the input connector. Used to generate the input under voltage and
over voltage alarm. See §6 for more details.
Default: 24V
Range: 11V … 28V
Resolution: 0.1V
5.2.2 BATTERY CHEMISTRY
Used to set the chemistry of the battery. The system support Lead Acid, Nickel and Lithium batteries. For
Lithium the battery pack used must include the protection and balancing circuitry.
Default: Pb
Choices: Pb, NiMh (CC/CV), Lith.(CC/CV)
5.2.3 BATTERY NOMINAL VOLTAGE
Used to set the nominal battery voltage.
Default: 24V
Range: 11V … 28V or input nominal voltage +20%
Resolution: 0.1V
5.2.4 BATTERY CAPACITY
Used to set the nominal battery capacity of the battery. The internal Coulomb counter uses this value to
indicate the state of charge of the battery.
Default: 2Ah
Range: 1.2Ah … 150Ah
Resolution: 0.1Ah
5.2.5 BATTERY CHARGE VOLTAGE
Used to set the maximum voltage used to charge the battery. See §3.6 for more details.
Default: 28.8V
Range: battery nominal voltage … 33V or battery nominal voltage +40%
Resolution: 0.1V
5.2.6 BATTERY CHARGE CURRENT
Used to set the maximum current used to charge the battery. See §3.6 for more details.
Default: 0.2A
Range: 0.2A … 5A
Resolution: 0.1A

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5.2.7 BATTERY DEEP DISCHARGE VOLTAGE
Used to set the deep discharge voltage of the battery. If the measured battery voltage drops below this
value the system disconnects it in order to prevent irreversible damage.
Default: 18V
Range: 8.2V … battery nominal voltage -25%
Resolution: 0.1V
5.2.8 BATTERY LOW VOLTAGE
An alarm is generated if during discharge the battery voltage drops below this threshold.
Default: 18V
Range: battery deep discharge voltage … 28V
Resolution: 0.1V
5.2.9 BATTERY NOMINAL INTERNAL RESISTANCE
Used to set the nominal battery internal resistance of the battery. When set to automatic the system will
record the next valid measurement as the nominal value. When set to disabled no alarm related to the battery
internal resistance will be generated.
Default: Disabled
Range: 1mΩ … 300mΩ, Disabled, Automatic
Resolution: 1mΩ
5.2.10 BATTERY MAXIMAL INTERNAL RESISTANCE VARIATION
Combined with the nominal internal resistance, it defines the threshold for the ALARM_BATTERY_RI_TOO_
HIGH.
Default: 200%
Range: 20% … 300%
Resolution: 1%
5.2.11 BATTERY MAXIMUM TEMPERATURE
An optional external temperature sensor (P/N: WNTC-2MT) is required. Used to set the maximum
temperature at which the battery can operate safely. If the measured temperature exceeds the set value, an
alarm is generated and the battery charging is stopped until the return under normal temperature level.
Default: 50°C
Range: 30°C … 80°C
Resolution: 1°C
5.2.12 BATTERY MINIMUM TEMPERATURE
An optional external temperature sensor (P/N: WNTC-2MT) is required. Used to set the minimum
temperature at which the battery can operate safely. If the measured temperature is lower than the set value,
an alarm is generated and the battery charging is stopped until the return under normal temperature level.
Default: -10°C
Range: -20°C … 0°C
Resolution: 1°C
5.2.13 BATTERY LIFETIME
Used to set the expected battery lifetime. Once the battery operating time exceeds the set value an alarm is
generated.
Default: 100kh
Range: 1kh … 200kh
Resolution: 1kh

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5.2.14 MAXIMUM BACKUP TIME
Used to set the maximum time the system stays in backup before switching OFF. If disabled the system
stays in backup until the battery reaches the deep discharge voltage.
Default: 2h
Range: 10s … 2h, No timeout
Resolution: 1s
5.2.15 INHIBIT POLARITY
Used to select the polarity of the INHIBIT input. The inhibit input prevents the system to enter the backup
mode.
Default: High
Choices: Low, High
5.2.16 SCREEN CONTRAST
Used to set the LCD screen contrast.
Default: 24
Range: 0 … 40
Resolution: 1
5.2.17 SCREEN BACKLIGHT
Used to set the LCD screen backlight.
Default: 2
Range: 1… 10
Resolution: 1
5.2.18 SCREEN TIMEOUT
To save the LCD backlight the system dims the LCD after the defined timeout value.
Default: 5min
Range: 1min … 30min, Disabled
Resolution: 1min
5.2.19 BUZZER STATE
Used to enable or disable the internal acoustic alarm buzzer.
Default: Enabled
Choices: Enabled, Disabled
5.2.20 DATE
Used to show and set the current RTC (Real Time Clock) date. The RTC is used to time stamp the event
logs.

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12 V / 24 V 20 A High Performance DC-UPS
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5.2.21 TIME
Used to show and set the current RTC time. The RTC is used to time stamp the event logs.
5.2.22 PC SHUTDOWN ENABLE
Enables the PC shutdown function as explained in §3.3.
Default: Disabled
Choices: Enabled, Disabled
5.2.23 PC SHUTDOWN DELAY
Delay between start of backup and PC shutdown command sent by POWERMASTER, see §3.3 for details.
Default: 0s
Range: 0s … 60min
Resolution: 1s
5.2.24 PC SHUTDOWN TIME
Delay between start of PC shutdown and output power OFF, see §3.3 for details.
Default: 0s
Range: 0s … 10min
Resolution: 1s
5.2.25 PC RESTART MINIMUM OFF TIME
Minimum OFF time for PC restart, see §3.3 for details. When set to 0 the PC restart function is disabled.
Default: 0s
Range: 0s … 60s
Resolution: 1s
5.2.26 PC OFF DETECTION CURRENT THRESHOLD
Current threshold for PC OFF detection, see §3.3 for details. When set to 0 the PC restart function is
disabled.
Default: 0A
Range: 0A … 20A
Resolution: 0.1A
5.2.27 PC OFF DETECTION TIMER
Timer user for PC OFF detection, see §3.3 for details.
Default: 1s
Range: 1s … 60s
Resolution: 1s

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5.2.28 RELAY 1 (READY)
Used to configure the behavior of the Relay 1 contact. Click OK and then follow the instruction on the screen
to define the polarity and event associated with the relay. See §3.1.3 for more details.
5.2.29 RELAY 2 (BACKUP)
Used to configure the behavior of the Relay 2 contact. Click OK and then follow the instruction on the screen
to define the polarity and event associated with the relay. See §3.1.3 for more details.
5.3 INFO
While in the info menu, use the UP/DOWN KEY to navigate through the menu items.
5.3.1 FIRMWARE VERSION
Shows the current firmware version. Using the freely available POWERMASTER software is possible to
upgrade the firmware with the latest available version.
5.3.2 SERIAL
Shows the device serial number (S/N). This serial number corresponds to the S/N shown on the device label.
5.3.3 NAME
Shows the device name. Using the freely available POWERMASTER software is possible to modify the
device name. The default name is DCU-20.
5.3.4 POWER ON CYCLES COUNTER
Shows the Power ON cycles counter, which is incremented by 1 every time the device is powered ON.