Functionality; Low Impedance Restricted Earth Fault Protection Refpdif - ABB REG670 Technical Manual

1MRK502052-UEN B
6.4
6.4.1
6.4.2
Technical manual
Function
Reset time at 5 to 0 x IdUnre
unrestrained function
Critical impulse time, unrestrained function
Impulse margin time unrestrained function
Operate time at 0 to 5 x IMinNegSeq
Negative sequence unrestrained function
Reset time at 5 to 0 x IMinNegSeq
Negative sequence unrestrained function
Low impedance restricted earth fault protection
REFPDIF
Identification
Function description
Restricted earth-fault protection, low
impedance

Functionality

Restricted earth-fault protection, low-impedance function REFPDIF can be used on
all directly or low-impedance earthed windings. The REFPDIF 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 59.
Differential protection
Range or value
Min. = 15 ms
Max. = 30 ms
2 ms typically at 0 to 5 x
IdUnre
10 ms typically
Min. = 25 ms
Max. = 35 ms
Min. = 30 ms
Max. = 45 ms
IEC 61850 IEC 60617
identification identification
REFPDIF
IdN/I
SYMBOL-AA V1 EN
Section 6
Accuracy
-
-
-
-
-
ANSI/IEEE C37.2
device number
87N
165