Non-Directional Instantaneous And Definitive Time, Phase And Residual Overcurrent Protection - ABB REC670 Applications Manual

Section 24
Requirements
24.1.6.2
602
I
³ = × ×
sr
E E 5 I
al alreq op
I
pr
EQUATION1380 V2 EN-US
where:
I The primary operate value (A)
op
I The rated primary CT current (A)
pr
I The rated secondary CT current (A)
sr
I The rated current of the protection IED (A)
r
R The secondary resistance of the CT (W)
ct
R The resistance of the secondary cable and additional load (W). The loop resistance
L
containing the phase and neutral wires, must be used for faults in solidly earthed systems.
The resistance of a single secondary wire should be used for faults in high impedance
earthed systems.
S The burden of an IED current input channel (VA). S
R
S =0.150 VA/channel for I
R
Non-directional instantaneous and definitive time, phase and residual
overcurrent protection
The CTs must have a rated equivalent limiting secondary e.m.f. E
than or equal to the required rated equivalent limiting secondary e.m.f. E
below:
³ = × ×
E E 1,5 I
al alreq op
EQUATION1381 V2 EN-US
where:
I The primary operate value (A)
op
I The rated primary CT current (A)
pr
I The rated secondary CT current (A)
sr
I The rated current of the protection IED (A)
r
R The secondary resistance of the CT (W)
ct
R
The resistance of the secondary cable and additional load (W). The loop resistance
L
containing the phase and neutral wires, must be used for faults in solidly earthed systems.
The resistance of a single secondary wire should be used for faults in high impedance
earthed systems.
S The burden of an IED current input channel (VA). S
R
S =0.150 VA/channel for I
R
æ ö
S
× + +
R
R R
ç ÷
ct L
2
I
è ø
r
=5 A
r
æ ö
I S
× + +
sr R
R R
ç ÷
ct L
2
I I
è ø
pr
r
=5 A
r
1MRK 511 401-UEN A
(Equation 128)
=0.020 VA/channel for I =1 A and
R r
that is larger
al
alreq
(Equation 129)
=0.020 VA/channel for I =1 A and
R r
Bay control REC670 2.2 IEC
Application manual
M11622-3 v5