Installation / Operation / Maintenance Manual
10/28/2019
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The Lake Shore undervoltage relay is also equipped with an inverse time delay on both “pickup” and “dropout” as shown in Figure
6. This time delay helps avoid nuisance undervoltage indications as may occur during system transients. The inverse time
characteristic allows a 1.5 second delay before the relay de-energizes when any phase falls just below the dropout setting. A 0.4
second delay occurs when any phase falls well below the dropout setting (20% or more).
Figure 6
