Eaton EMR-3MP0 - Current Unbalance Protection; Commissioning: Current Unbalance Module

4.10 46 - Current Unbalance Protection
The 46 device Current Unbalance protection calculates the positive and negative
sequence currents from the 3-phase currents. The Threshold setting de󰊎nes a minimum
operating current magnitude of either I1 or I2 for the 46 function to operate, which
ensures that the relay has a solid basis for initiating a current unbalance trip. The »%
(I2/I1)« setting is the unbalance trip pickup setting. It is de󰊎ned by the ratio »%(I2/I1)« of
negative sequence current to positive sequence current. (Of course, the determination of
positive and negative sequence currents takes into account the phase sequence setting
at [System Para] »Phase Sequence«.)
This function requires a negative sequence current magnitude above the threshold
setting and the percentage current unbalance above the »%(I2/I1)« setting before
allowing a current unbalance trip. Therefore, both the threshold and percent settings
must be met for the speci󰊎ed delay time setting before the relay initiates a trip for
current unbalance.
46
NPSI_E91
2
Please Refer to Diagram: Blockings
(Element is not deactivated and no active blocking signals.)
46 . Pickup
Φ
PPS
NPS
Filter
IB
46 .
Threshold
46 . Trip
IA
IC
46 .
%(I2/I1)
AND
AND
─────────────
t
0
14
15
Yes
46 .
Alarm only
No
AND
AND
Trip
↪ »Prot«
Pickup
↪ »Prot«
I2
%(I2/I1)
◄
46 = 46[1]...[2]
46 .
t
4.10.1
Commissioning: Current Unbalance Module
Object to be tested:
Test of the unbalanced load protection function.
Necessary means:
• Three-phase current source with adjustable current unbalance; and
• Timer.
Procedure:
Check the phase sequence:
• Ensure that the phase sequence is the same as that set in the 󰊎eld parameters.
• Feed-in a three-phase nominal current.
176 www.eaton.com EMR-3MP0
4 Protective Elements
4.10 46 - Current Unbalance Protection