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I< Phase Undercurrent Protection Menu
Phase Undercurrent Protection is symbolized as I< in
IEC Standards, and coded as 37 in IEEE/ANSI
Standards.
I< symbol indicates that the protection function
monitors the phase current and intervenes when
current values below the 1
st
threshold are detected.
Phase undercurrent protection may be needed for
some specific applications, such as, breaking of the
primary supply line of a water pump when there is no
water to be pumped and the consumption of the motor
falls below a predefined level close to idle consumption.
The picture shows the Phase Undercurrent Protection
Menu and the menu comprises 3 parameters.
Protection
Can be set as “Active” or “Passive”, to have the protection into or out of service.
I< (Threshold)
Indicates the threshold value for the protection function. For I<, the set value range is (0.02-1.00) I
n
with steps of 0.01 I
n
. I
n
is the phase nominal current value of the current transformer.
tI< (Tripping Delay)
The tripping delay of Phase Undercurrent Protection function is DMT. The term “tI<” describes the
tripping delay once any of the phase current values fall below the I< threshold. The range is (0.01-
150.00) s, and the stepping is 0.01 s. □
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