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DMC3S - Manual - 08 - 2021
— Direct undervoltage - 27CC
Preface
The protection has an adjustable, delayable threshold with definite time characteristic.
Measurement criterion
The protection measures the panel's auxiliary power voltage (U
aux
):
Operation and settings
The measured voltage is compared with the threshold setpoint; when the measured voltage drops
below a set threshold the threshold itself starts (Start) and the respective timer starts counting.
If the condition persists, when the operating time expires, the threshold trips (Trip), otherwise the
threshold is reset.
The protection threshold can be enabled or disabled by setting to ON or OFF the parameter UCC<
Enable in the menu Set \ Protections \ Direct undervoltage - 27CC \ Threshold UCC< \ Parameters
and/or State in the menu Set \ Protections \ Direct undervoltage - 27CC \ Threshold UCC< \ Definite
time.
Logical block (Block1)
If parameter UCC<BLK1 is set to ON and an input is configured with the block function, the re-
spective threshold is blocked for a time equal to the operating time for the logical input itself. In
particular, the trip timer is held in the reset condition, so that the trip timer only starts counting when
the block signal expires.
The enable parameter can be set in the menu Set \ Protections \ Direct undervoltage - 27CC \ Thresh-
old UCC< \ Parameters, while the block function is mapped to the input in the menu Set \ Input board
inputs \ Input IN1-1, (Input IN1-x).
General characteristic of the minimum DC voltage function - 27CC(80.S)
UCC
UCC<
tUCC<
t
TRIP
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