Technical Data; Numerical Stabilized Low Impedance Restricted Earth-Fault Protection 87L0Zref; Identification; Function Block - ABB RELION 620 Series Technical Manual

Section 4
Protection functions
4.6.2.11
4.6.3
4.6.3.1
4.6.3.2
4.6.3.3
456

Technical data

Table 349: 87T3 technical data
Parameter
Pickup accuracy
1)2)
Pickup time
Low stage
High stage
Reset time
Reset ratio
1) Current before fault = 0.0 × In, f
2) Includes the delay of the output contact value. f
Numerical stabilized low impedance restricted earth-fault
protection 87L0ZREF

Identification

Function description
Numerical stabilized low impedance
restricted earth-fault protection

Function block

GUID-136BBBB5-17AB-41B1-81B9-F89CC3E05227 V2 EN
Figure 208: Function block

Functionality

Numerical stabilized low impedance restricted earth-fault protection 87LOZREF for a
two winding transformer is based on the numerically stabilized differential current
principle. No external stabilizing resistor or non-linear resistor are required.
Accuracy/value
Depending on the frequency of the current measured: f
±3.0% of the set value or ±0.002 × I
Minimum
34 ms
19 ms
<40 ms
Typically 0.96
= 60 Hz. Injected differential current = 2.0 × set trip value.
n
= 60 Hz.
n
IEC 61850 IEC 60617
identification identification
LREFPNDF dIoLo>
1MAC504801-IB E
n
Typical Maximum
39 ms 44 ms
21 ms 22 ms
ANSI/IEEE C37.2
device number
87LOZREF
620 series ANSI
Technical Manual
±2 Hz
n