ABB Relion 670 series - Functionality; Identification; Low Impedance Restricted Earth Fault Protection REFPDIF (87 N)

Function Range or value Accuracy
Impulse margin time unrestrained
function
10 ms typically -
Trip time at 0 to 5 x IMinNegSeq
Negative sequence unrestrained
function
Min. = 25 ms
Max. = 35 ms
-
Reset time at 5 x IMinNegSeq to 0
Negative sequence unrestrained
function
Min. = 30 ms
Max. = 45 ms
-
6.4 Low impedance restricted earth fault protection REFPDIF
(87N)
IP14640-1 v6
6.4.1 Identification
M14843-1 v5
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Restricted earth-fault protection,
low impedance
REFPDIF
IdN/I
SYMBOL-AA V1 EN-US
87N
6.4.2 Functionality
IP12418-1 v2
M13047-3 v18
Restricted fault protection, low-impedance function REFPDIF (87N) can be used on all solidly or
low-impedance grounded windings. The REFPDIF (87N) function provides high sensitivity and high
speed tripping as it protects each winding separately and thus does not need inrush stabilization.
The REFPDIF function is a percentage biased function with an additional zero sequence current
directional comparison criterion. This gives excellent sensitivity and stability during through
faults.
REFPDIF can also protect autotransformers. Five currents are measured at the most complicated
configuration as shown in Figure
62.
Section 6 1MRK 502 066-UUS B
Differential protection
166
Technical manual