5
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Function description
Wieland Electric GmbH | BA001052 (Rev. A) | 11/2018
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5.3
Current limit
The UPS module has the ability to limit the current flowing through its input, output and battery terminals
to a user settable threshold.
5.3.1
Current limit in UPS mode
In UPS mode the UPS module provides 4 different settings for the current limit:
•
Maximum input current
(see no. 21 in section 6.2), default 20 A: it is used to limit the input
current at a specified threshold. For example, if the DC power supply is rated less than 20 A, the
threshold can be lowered to avoid too high current drain from the power supply. When the input
current limit is reached, the battery charging current is limited. If the input current cannot be kept
below the threshold due to excessive loading, an input overcurrent alarm is triggered. When the
input current is approaching the threshold, the measured input current is displayed with red fonts
on the LCD.
•
Maximum output current
(see no. 22 in section 6.2), default 20 A: it is used to limit the maximum
current delivered to the load. When the threshold is reached due to excessive loading, an output
overcurrent alarm is triggered. When the output current is approaching the threshold, the meas-
ured output current is displayed with red fonts on the LCD.
•
Battery maximum charge current
(see no. 7 in section 6.2), default 0.5 A (maximum settable
20 A): it is used to limit the maximum charge current supplied to the battery. This threshold will
be automatically reduced in such manner that the maximum input current limit (see no. 21 in
section 6.2) is distributed to the load with priority towards the charging.
For example, if the maximum input current limit is 20 A and the load needs 10 A while the maxi-
mum charge current is set at 12 A, the controller will limit the charging current automatically to
10 A until the load will need <10 A.
•
Battery maximum discharge current
(see no. 11 in section 6.2), default 20 A: it is used to limit
the maximum discharge current delivered from the battery during the backup function. When the
threshold is reached due to excessive loading, a battery overcurrent alarm is triggered and the
output voltage starts to decrease. When the battery discharge current is approaching the thresh-
old, the measured battery current is displayed with red fonts on the LCD.
5.3.2
Current limit in DC-DC mode
In DC-DC mode the UPS module provides 2 different settings for the current limit:
•
Maximum input current
(see no. 21 in section 6.2), default 20 A: it is used to limit the input
current at a specified threshold. For example, if the DC power supply is rated less than 20 A, the
threshold can be lowered to avoid too high current drain from the power supply. When the input
current limit is reached due to excessive loading, an input overcurrent alarm is triggered. When
the input current is approaching the threshold, the measured input current is displayed with red
fonts on the LCD.
•
Maximum output current
(see no. 22 in section 6.2), default 20 A: it is used to limit the maximum
current delivered to the load. When the threshold is reached due to excessive loading, an output
overcurrent alarm is triggered and the output voltage starts to decrease. When the output current
is approaching the threshold, the measured output current is displayed with red fonts on the LCD.
5.4
Inhibit
An
opto-isolated input
allows the inhibition of the backup function in UPS mode or switching off the
output on DC-DC mode. The polarity of the input can be defined using the "Inhibit polarity" field. See no.
28 in section 6.2 for more details.
