Protection - frequency, Figure 398, N figure 399 – Basler Electric BE1-11m User Manual
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Figure 398. Logic Pickup / Dropout Timers Screen
Figure 399. Power Factor (55) Screen
Protection - Frequency
Two frequency protection elements monitor for underfrequency and overfrequency conditions. According
to the NEMA MG-1 standard, motors are expected to operate successfully under running conditions at
rated load with a variation of
±10 percent of rated voltage, ±5 percent of rated frequency, or a combination
of the two, provided the sum of the absolute values of the deviations does not exceed 10 percent and the
frequency variation does not exceed
±5 percent.
Underfrequency (81-1)
The 81-1 protection element alarms when the source frequency is 5 percent below nominal. A time delay
of 100 ms is used to avoid nuisance alarms. The pickup setting is calculated in Equation 82.
𝑃𝑖𝑐𝑘𝑢𝑝 = (100 − 5%) ∙ 𝑁𝑜𝑚𝑖𝑛𝑎𝑙 𝐹𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 = 0.95 ∙ 60 = 57 𝐻𝑧
Equation 82. 81-1 Pickup
Select Under mode, set the Pickup setting to 57 Hz, and set the Time Delay to 100 ms as shown in Figure
400.
BE1-11m
Settings Calculation Examples