EMR-4000
IM02602009E
81O/U, 81R, 78V - Frequency Protection
Available elements:
81[1] ,81[2] ,81[3] ,81[4] ,81[5] ,81[6]
All frequency protective elements are identically structured.
Frequency - Measuring Principle
The frequency is calculated as the average of the measured values of the
three phase frequencies. Only valid measured frequency values are taken
into account. If a phase voltage is no longer measurable, this phase will be
excluded from the calculation of the average value.
The measuring principle of the frequency supervision is based in general on the time measurement of complete cycles,
whereby a new measurement is started at each zero passage. The influence of harmonics on the measuring result is
thus minimized.
Frequency tripping is sometimes not desired by low measured voltages which, for instance. occur during alternator
acceleration. All frequency supervision functions are blocked if the voltage is lower 0.15 times Vn.
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621
V(t)
t
T
T
Содержание EMR-4000
Страница 61: ...EMR 4000 IM02602009E Ethernet RJ45 Terminal Marking www eaton com 61 1 8 TxD TxD RxD N C N C RxD N C N C...
Страница 423: ...EMR 4000 IM02602009E Name Description Logic LE23 Out inverted Signal Negated Latched Output Q NOT www eaton com 423...
Страница 493: ...EMR 4000 IM02602009E Motor Protection Curves Motor Protection Curve Example 1 www eaton com 493...
Страница 494: ...EMR 4000 IM02602009E Motor Protection Curve Example 2 without RTDs www eaton com 494...
Страница 495: ...EMR 4000 IM02602009E Motor Protection Curve Example 3 with RTDs www eaton com 495...