Unipower ARR-M Series, Руководство по эксплуатации продукта

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BATTERY CHARGER USER’S MANUAL PART- 2: THEORY OF OPERATION
MCEnPC23-REV.2.4 Page 42
f. Load Sharing (optional)
Two or more chargers may be used in parallel to share the same load and recharge the same battery. This parallel
configuration is meant to improve site reliability and ease the routine service during shutdowns and preventive
maintenance. So should one charger fail or being disconnected, the other charger will take over. Ideally, chargers
and connected charging circuits, including cabling, must be symmetrical in order to keep the same voltage drop.
The chargers are usually sized to supply the load while recharging the battery when only one charger is available.
Consult with the design engineer for the sizing rational.
In order to compensate for the different component, wiring and sensing characteristics, forced load sharing is
introduced to force 2 identical chargers to share the load as equal as possible. The dynamic “negative slope load
sharing” is designed to force 2 chargers to share the common load without having any common control circuit, thus
preventing “Single Point Failure”:
NO COMMON CONTROL WIRING IS REQUIRED AND NO MASTER
(PRIMARY) CHARGER SET UP IS REQUIRED.
Instructions and requirements:

Insure that redundant chargers are fed by equivalent AC input voltages;

Proper AC and DC protection coordination must be done by others, especially for the chargers contribution
in case of input or output short circuit event.

Load sharing between 2 similar chargers with similar control boards and software version and filter circuit,
is approximately 10% when chargers are operated between 10% and their current limit.

In order to compensate for the non-symmetrical cabling which may induce non-symmetrical voltage drops,
chargers Float and Equalize voltages must be site fine-tuned to read the same current (50% of total load
current) whenever it is possible. Ideally, the chargers must be running at more than 10% to 20% of their
nominal output current. Example: 100mV to 200mV fine-tune on a 125VDC system would be sufficient.

Equal load sharing on more than 2 chargers is not tested.

Power cables for chargers, load and battery interconnections are provided by others.
If temperature compensation option applies to both battery chargers with load sharing option, observe all safety
precautions and follow sensor installation instructions as described in (
Page 43, § g) .
Sensors shall be placed together in one
spot to avoid temperature gradient. Cable length for both sensors shall be
equal.
We can enable or disable Load Sharing option as shown on the procedure below: