nextys DCW20, Short Form Installation Manual, Page: 3 / 7

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Operating MODE
UPS Mode
UPS Mode:
In UPS mode the DCW20 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 DCW20 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 DCW20 takes energy from the battery to keep the
output regulated at “ Nominal output voltage ”.
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 estimate of the
residual charge of the battery.
Backup starts when the output voltage is lower than 90% of the “ Nominal output
voltage ”.
Battery charger:
The battery charger supports various chemistries such Lead-Acid, Nickel, Lithium
and Super-capacitors. 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.
Warnings:
- In order to avoid potentially hazardous situations including fire hazard, safety recommendations must be followed. Only authorized staff can install the unit.
- 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.
DC-DC Mode
DC-DC Mode:
DCW20 can be used as a high performance DC/DC converter. An example of
DC/DC connection is given on to the side.
Any voltage between 10V to 55V can be converted to any voltage between 10V
to 55V (step-up and step-down operation) with up to 20A input or output
current.
Input and output are protected against over current with user settable limits.
When used as a DC/DC converter the input supply must be connected to the
battery connector as shown on to the side.
Additional Functions
Battery health monitor
•
Internal resistance 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.
•
Temperature 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 or under temperature the system disconnects the
battery to prevent damage.
• Coulomb counter : Estimates 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.
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.
This practice is also a method to see if the battery connected to the DCW20 is functional. In cold start the DCW20 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 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 DCW20:
• Press and hold simultaneously the and buttons until you see the welcome message on the screen. On the status screen the "Cold start” text is written beside
the input icon.
• Release the buttons.
PC shutdown and automatic restart:
•
PC shutdown: In case the DCW20 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 Modbus. Optionally POWERMASTER can call a task on the PC before shutting down,
for example to backup some sensitive data.
• Automatic restart: DCW20 is able to automatically restart a PC which was powered OFF by mistake, for example in case of the Operating System (OS) crash. The