Eaton EMR-3MP0 Installation, Operation And Maintenance Manual page 170

4 Protective Elements
4.8 50P – DEFT Overcurrent Protection
50P
50P = 50P[1]...[2]
Please Refer to Diagram: Blockings
(Element is not deactivated and no active blocking signals.)
4
True RMS
IA Φ
IB
IC
50P .
Alarm only
No
Yes
IOC Function
The instantaneous overcurrent function (IOC) or 50P[x] is intended to protect in the event
of a high-current fault. The example IOC setting used in the Motor Protection Curve (see
the Motor Protection Curve Examples in the Ultimate Trip Current Section) is 12 times
(1200%) of FLA. In general, the instantaneous IOC should be at least 1.5 times LRC, well
above the locked rotor current normally seen at the moment of a start.
IOC should trip fast and therefore no run or pickup delay is provided. A start delay is set
at a minimum of two cycles (0.03 seconds), or more if needed to block IOC tripping on
magnetizing inrush when the motor is first energized. An additional IOC time delay setting
is set at a default of zero seconds.
The IOC sets the instantaneous overcurrent trip limit in percentage of the FLA above at
which the relay trips. This trip type can be set to Inactive to deactivate this protective
device element. For currents clearly above the setting, the IOC function picks up in two
power cycles or less. The IOC setting must be below (1.130 ⋅ PCT/ FLA) or 1.600%,
whichever is less.
170
50P .
Pickup
◄
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AND
AND
AND
OR
50P .
t
t
0
AND
AND
Pdoc_E98
50P . Pickup IA
24a
50P . Pickup IB
25a
50P . Pickup IC
26a
50P . Pickup
50P . Trip
Pickup
↪ »Prot«
14
Trip
↪ »Prot«
15
EMR-3MP0