Parameter: 27 Common > UV Guard Setting
•
Default setting: 5 V
When the measured voltage of all inputs is below this setting operation of the 27 function elements can
be blocked.
Parameter: Element
•
Default setting: Disabled
This setting is used to allow the element to be switched on or off if it is not required.
Parameter: Pick-Up Option
•
Default setting: Any
This setting defines whether the element picks up if the required voltage conditions are detected on any
1 phase Any or if they must be detected on all 3 phases All.
Parameter Value Description
Any This setting will allow detection during unbalanced
voltage conditions and will operate for the worst
phase. This is the appropriate setting for most appli-
cations.
All This setting is commonly used when the element is
used to detect loss of supply or for extra immunity
from unbalance deviations.
Parameter: Setting
•
Default setting: 80 V
This is the operating voltage threshold of the element, the element will pickup if the voltage falls below
this value. This should be set to suit the individual application.
Parameter: Hysteresis
•
Default setting: 3 %
This sets the drop-off threshold for the undervoltage element. The element will pickup if the voltage falls
below the setting and will reset when the voltage recovers to the setting + hysteresis voltage. This setting
is a percentage of the undervoltage setting.
The default setting of 3 % is generally enough to avoid chatter of the element but care may be required
for settings which are close to the nominal value otherwise the element may not reset when the voltage
recovers to nominal value as the voltage is still in the hysteresis window.
Parameter: Delay
•
Default setting: 0.1 s
This is the time delay setting for the DTL element. This should be set to suit the individual application.
Parameter: UV Guard Inhibit
•
Default setting: Yes
This setting selects whether operation is blocked for measured voltages below setting. This is typically
used to avoid nuisance operations whenever the circuit is de-energized. It is recommended that this
setting is used unless the element is being applied as dead line or loss of supply detection.
Protection and Automation Functions
5.2 27 Undervoltage Protection – 3-Phase
152 Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019
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