ERL L-PRO 4000, User Manual

Page: 90 / 406

4 Protection Functions and Specifications
4-40 L-PRO 4000 User Manual D02706R02.30
50N/51N/67
Neutral
Overcurrent
Neutral overcurrent provides backup protection for line to ground faults. The
user can define directional or non directional control on either 50N or 51N
functions. 51N can also be configured for use in the communication scheme.
All the curve definitions are the same as the phase overcurrent except that this
function uses 3I0 rather than phase current. The equation is:
All parameters for Equations 5 and 6 are defined in Table 4.23: 50N/51N/67
Neutral Overcurrent Settings on page 40.
For 3
I0
> pickup (7)
For 3
I0
< pickup
(8)
Table 4.23: 50N/51N/67 Neutral Overcurrent Settings
50N Enable/Disable
Directional Directional, non-directional, combined
Pickup (3I
0
) 0.25 to 50.00 (5 A)
0.05 to 10.00 (1 A)
Pickup Delay 0.00 to 99.99 seconds non-directional
0.01 to 99.99 seconds directional
51N Enable/Disable
Directional Directional, non-directional, combined or direction in scheme
Pickup (3I
0
) 0.25 to 50.00 (5 A)
0.05 to 10.00 (1 A)
Curve Type For details see Table 4.21: IEC and IEEE Curves on page 38.
TMS 0.01 to 10.00
A 0.0010 to 1000.0000
B 0.0000 to 10.0000
p 0.01 to 10.00
TR 0.10 to 100.00
Directional Angle Setting
Alpha -179.90 to 180.00
Beta 0.10 to 360.00
T 3 I 0
 
TMS B
A
3 I 0
Pickup
------------------
 
 
p
1 –
------------------------------------ + =
T 3 I 0
 
TMS
TR
3 IO
Pickup
------------------
 
 
2
1 –
----------------------------------- =